<%BANNER%>

The Relationship of Fear-Avoidance to Disability: A Quantitative Review


PAGE 1

1 THE RELATIONSHIP OF FEAR-AVOI DANCE TO DISABILITY: A QUANTITATIVE REVIEW By ALISA DIANE HASSINGER A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2007

PAGE 2

2 2007 Alisa Diane Hassinger

PAGE 3

3 ACKNOWLEDGMENTS I thank my supervisory committee chair, Dr. Michael Robinson, for his invaluable guidance and mentoring. I would also like to tha nk the members of the Center for Pain Research for their help and support.

PAGE 4

4 TABLE OF CONTENTS page ACKNOWLEDGMENTS...............................................................................................................3 LIST OF TABLES................................................................................................................. ..........5 ABSTRACT....................................................................................................................... ..............6 CHAPTER 1 INTRODUCTION................................................................................................................... .7 Chronic Low Back Pain: A Statement of the Problem............................................................7 The Fear-Avoidance Model of Exaggerated Pain Perception..................................................8 2 METHODS........................................................................................................................ .....12 3 RESULTS........................................................................................................................ .......18 4 DISCUSSION AND CONCLUSIONS..................................................................................25 LIST OF REFERENCES............................................................................................................. ..30 BIOGRAPHICAL SKETCH.........................................................................................................35

PAGE 5

5 LIST OF TABLES Table Page 2-1 Excluded Studies........................................................................................................... .....16 2-2 Included Studies........................................................................................................... ......17 3-1 Baseline Correlations between Fear-Avoidance and Disability........................................21 3-2 Significance and Effect Sizes of Studies with Continuous Variables................................22 3-3 Significance and Effect Sizes of Studies with Dichotomous Variables............................23 3-4 Significance and Effect Size of Studies Measuring Change..............................................24

PAGE 6

6 Abstract of Thesis Pres ented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science THE RELATIONSHIPS OF FEAR-AVOIDANC E TO DISABILITY: A QUANTITATIVE REVIEW By Alisa Diane Hassinger May 2007 Chair: Michael Robinson Major: Psychology Pain-related fear and its attendant avoidan ce behaviors have been identified as key psychosocial variables in the development and maintenance of chronic low back pain. A growing number of prospective stud ies have indicated that fear-avo idance models are useful in predicting long-term disab ility. However, longitudinal data have yielded varying and sometimes conflicting results. A systematic quantitative review of prosp ective studies was conducted to examine the effect sizes of fear avoidance variable s in the prediction of disability in patients with low back pain. A literature search resulted in 12 studies which met initial inclusion criteria. Analyses revealed that while fear avoidance variables typica lly share moderate zero order correlations with disability measured at baseline, effect sizes decrease to small effects over time, particularly when controlling for re levant variables such as initial pain intensity, or psychosocial variables such as distress. This pattern of re sults indicates that fear avoidance variables may share substantial statistical and conceptual overl ap with other psychosocia l variables and may be best viewed as part of a larger psychosocial model, rather than as independent predictors of disability.

PAGE 7

7 CHAPTER 1 INTRODUCTION Chronic Low Back Pain: A Statement of the Problem Pain is one of the most common reasons peopl e seek medical attention (Schappert, 1989). When pain becomes chronic, there are se rious negative consequences for physical, psychological, and social functioning, with deleteri ous effects noted in both work and family life (Turk, 2001). Low Back Pain (LBP) is one of the most co mmon forms of pain reported (Mantyselka et al.., 2001; Sternbach, 1986), with 53% of adults in the general population experiencing some disability from LBP in a six month period (Walker, Muller, & Grant, 2004). LBP is a significant source of cost to both the i ndividual and society, associated with increased healthcare expenditures and lost productivity (Anderss on, Ejlertsson, Leden, & Rosenberg, 1993; Stang, Von Korff, & Galer, 1998; Stewart, Ricci, Chee, Morganstein, & Lipton, 2003; Tacci, Webster, Hashemi, & Christiani, 1998; Walker et al.., 2004). It has long been asserted that only a small percentage of patients who experience an acu te episode will devel op chronic LBP (Watson, Main, Waddell, Gales, & Purcell-Jones, 1998). However, recent data su ggests that acute LBP evolves into a chronic or recurrent condition more frequently than previously suspected (Hestbaek, Leboeuf-Yde & Manniche, 2003). Chronic LBP, with an estimated prevalence of 15 to18% in the adult population, is of special concern (Frank et al.., 1996). The cost of chronic LBP to society has been estimated at $18 billion annually (Linton & va n Tulder, 2001), a figure which distinguishes chronic LBP as the most expensive benign medical condition in industrialized countries (Mayer, 1991). The associated prevalence and costs highlight chroni c LBP as an important public health concern,

PAGE 8

8 and underscore the need for research focused on th e identification and treatm ent of those at risk for developing chronic LBP. Because an underlying physical pathology responsible for the development and maintenance of chronic LBP has not been discover ed in the majority of patients who suffer with this condition, the development of biomedically oriented preventi on and treatment strategies has not been successful (Hart, Deyo, & Cherkin, 1995; Linton & van Tulder, 2001; Loeser, 1994). Randomized, clinical trials have repeatedly shown that commonly used strategies intended to prevent the development of LBP, such as back schools, lumbar supports, and ergonomic interventions, are ineffectiv e (Linton & van Tulder, 2001; Scheer, Radack, & O'Brien, 1995). However, studies have consistently identifie d psychosocial factors rather than physical impairments as better predictors of which patien ts will develop chronic disability from an acute episode of LBP (Burton, Tillotson, Main, & Hollis 1995; Frank et al.., 1996; Gatchel, Polatin, & Mayer, 1995; Pincus, Burt on, Vogel, & Field, 2002) The Fear-Avoidance Model of Exaggerated Pain Perception The Fear-avoidance Model of Exaggerated Pa in Perception (FAMEPP), first proposed by Lethem and colleagues in 1983, has been posited as one explanation for why a subgroup of patients develop chronic LBP and its attendant disability (Lethem, Slade, Troup, & Bentley, 1983; Slade, Troup, Lethem, & Bentley, 1983). This model proposes that fear-avoidance beliefs and pain catastrophizing are the primary psychosoc ial factors responsible for the development of chronic LBP symptoms. More specifically, a patients re sponse to LBP can fall along a continuum of confrontation to avoidance. A c onfrontation response is vi ewed as adaptive as it supports the patients participation in daily so cial and vocational activ ities, encouraging a recovery of function. An avoida nce response to pain results from higher levels of pain related fear and avoidance, and has nega tive psychological and physical c onsequences for the individual.

PAGE 9

9 Psychologically, exaggerated pain perception results from elevated levels of fear (George, Dannecker, & Robinson, 2006; George, Wittmer, F illingim, & Robinson, 2007). Patients also may develop depressive and anxious symptoms as a result of their perc eived loss of function, factors which are known to be associated with decreased pain tolera nce (Vlaeyen & Linton, 2000). Physically, patients with LBP experien ce disuse syndrome (decr eased spine range of motion, loss of muscle force, and we ight gain) as a result of their avoidant response to the fear of pain (Bortz, 1984; Kottke, 1966; Lethem et al .., 1983; Slade et al.., 1983). A continuous feedback loop is therefore created in which the patients elevated fear results in avoidant behavior, which consequently leads to increas ing disability, emotional distress, and the maintenance of the fear and avoidance. Vlaeyen and colleagues have further elabor ated on this model by proposing a Cognitive Model of Fear of Movement/(Re)injury (Vlaey en, Kole-Snijders, Boeren, & van Eek, 1995). This model conceptualized the pain related fear as a specific fear of movement, particularly that which the patient believes may result in further in jury. This model also highlights the role of pain catastrophizing, defined as the belief that the pain experience will lead to the worst possible outcome (Sullivan et al.., 2001), as a psychosocial variable which increases the patients fear of movement and subsequent avoidance behaviors (Vlaeyen & Linton, 2000). Initial investigations have consistently demons trated that elevated levels of pain related fear and avoidance are associated with the development and maintenance of chronic low back pain and its attendant disability. A study by Crombez and colleagues in 1998 categorized subjects as having either a confrontational or avoidance coping styl e, and found that those classified as Avoiders had greater pain related fear and levels of disability, and more difficulty with physical activities (Crombez, Vervaet, Lysens, Baeyens, & Eelen, 1998). Further evidence

PAGE 10

10 of the relationship of pain related fear and f unctional limitations has been found in studies investigating the performances of patients with CLBP during a task which measured walking speed (Al-Obaidi, Al-Zoabi, Al-Shuwaie, Al-Zaa bie, & Nelson, 2003) and a lifting task (Vlaeyen et al.., 1995). A growing body of literature exists which has demonstrated a relationship between higher levels of fear-avoidance and gr eater levels of disability (Asmundson, Norton, & Allerdings, 1997; Crombez, Vlaeyen, Heuts, & Lysens, 1999; Severeijns, Vlaeyen, van den Hout, & Weber, 2001; Waddell, Newton, Henderson, Somerville, & Main, 1993). However, much of the research performed has been, until recently, cross sectional in nature, and thus unable to establish a causal rela tionship between elevated pain related fear and the development of chronic LBP disability. In 1995, Klenerman and colleagues published the first prospective study examining the relations hip between these vari ables, and found higher levels of pain related fear to be a significant co ntributor to chronic LBP disability (Klenerman et al.., 1995). Many of the prospective studies which followed also found this relationship (Boersma & Linton, 2006; Fritz, George, & De litto, 2001; George, Frit z, Bialosky, & Donald, 2003; Picavet, Vlaeyen, & Schouten, 2002; Wo by, Watson, Roach, & Urmston, 2004). However; the results of these studies were mo re mixed than those of the cross sectional examinations. Several studies were unable to find significant prospectiv e relationships between pain related fear, and disabil ity (Grotle, Vollestad, & Brox, 2006; Grotle, Vollestad, Veierod, & Brox, 2004; Sieben et al.., 2005; Staerkle et al.., 2004). Aims and Hypotheses Although it appears that both cross sectional a nd prospective studies have indicated that fear-avoidance beliefs may play a role in th e development of chroni c LBP disability, the magnitude of these effects has not been systemat ically examined in the literature. With a

PAGE 11

11 growing body of prospective literatur e, it is an opportune time to i nvestigate the strength of the relationship between fear-avoidan ce beliefs and disability in order to guide future research endeavors. Our study proposes a qua ntitative review of the prospect ive literature to examine the relationship between fear avoida nce variables measured at base line and a follow-up time point, with the intention of assessing th e magnitude of the relationship between pain related fear and disability. The first aim of our study was to examine the relationship of fear-avoidance variables to initial disability ratings in patients with LBP. We hypothesize that fear -avoidance variables will be highly correlated with measures of disability. The second aim is too assess th e effectiveness of the fear-a voidance model in predicting later disability in patients with LBP. We hypothesize that fear-a voidance variables will demonstrate large effect sizes in models predicting later LBP related disability.

PAGE 12

12 CHAPTER 2 METHODS A review of the literature was undertaken to identify prospective studies using Fearavoidance Beliefs as an independent variable predicting a measure of disability. A Medline database search was conducted using the followi ng search terms: Pain, Fear-avoidance; Pain, Kinesiophobia; Pain, Fear of M ovement/(Re)Injury. A publicati on cutoff date of September, 2006, was used; however, no backward cutoff date was specified. Add itional articles were identified using the bibliographies of th e studies located thro ugh Medline database. Twenty-five studies were initially identified for inclusion in th e review. Because this is a small but increasing body of resear ch available with a relatively ne w construct, liberal exclusion criteria were developed. The first exclusion crit erion precluded the inclusion of multiple studies which used the same data set. When these st udies were identified, only the first study published using the data was included. This resulted in th e exclusion of two studies. An exception to this criterion was made for the two studies conducted by Grotle et al.., as th e second study added an additional population and used a different method of analysis. The second exclusion criterion required that studies use standardized instruments to measure Fear-avoidance Beliefs and Disability in order to be included in the review. Studies with non-standardized instrument s were permitted if they provided pilot data for the measure they selected. Two studies were excluded for th e use of non-standard measures. Because the great majority of the literature has addressed only back pain, the use of a mixed pain population was the third basis for exclusion, disqualifying three studies. The fourth cr iterion required that studies use a sample size of 10 or more subjects. This resulted in the ex clusion of four studies with sample sizes of four, six, six, and eight. After exclusion criteria were applied, 14 studies were eligible for inclusion. A summary of the excluded studies can be found in Table 2-1.

PAGE 13

13 Analyses were planned to examine the correl ations between fear-a voidance variables at baseline, and to calculate effect size estimates in order to examine the st rength of the relationship between the fear-avoidance variables and measures of disability after a peri od of time. Of the 14 eligible studies, two were deemed to contain sufficient data at publication to allow for the strength of the relationship be tween fear-avoidance and disabili ty to be examined at both baseline and follow-up. Therefore, twelve e-ma il requests were made to corresponding authors to obtain the additional data re quired for the planned analyses. Of the twelve requests, one author could not be reached, and two authors did not respond. However, one of these articles contained enough information for one of the two planned analyses, and therefore was included. In total, twelve articles were included in th e final review, with ten studies examining fearavoidance variables as predictors of disability and two studies usi ng an observed change in fearavoidance variables as predicto rs of change in disability. The studies reviewed included both acute and chronic pain p opulations recruited from a variety of settings, including prim ary care clinics, pain clinics, and general population surveys. The number of subjects included in the studies ranged from 54 to 1,571. Subjects were followed for time periods ranging from one month to two y ears. A summary of included studies can be found in Table 2-2. All studies measured the i ndependent variable of pain re lated fear by the administration of one of two standard self-re port questionnaires: the Fear-avoidance Beliefs Questionnaire (FABQ) or the Tampa Scale of Kinesiophobia (TSK ). The Fear-avoidance Beliefs Questionnaire (FABQ) is a measure described by Waddell and co lleagues (Waddell et al.., 1993). It contains 16 items, each scored on a 6-point Likert scale with higher numbers indicating increased levels of fear-avoidance beliefs. Two subscales have been identified within the FABQ: a seven-item

PAGE 14

14 work subscale and a four-item physical activit y subscale. The TSK (Miller RP, 1991) is a 17 item self report questionnaire with items scored on a 4-point Likert scale. Recent investigations have indicated that the TSK can be divided into two subscale which describe the contructs of somatic focus (five items) and activity avoidanc e (eight items)(Goubert et al.., 2004; Roelofs, Goubert, Peters, Vlaeyen, & Crombez, 2004). The dependent variable of disability was measured using a variety of methods, both dichotomous and continuous. Dichotomous measur es included work status, and self report measures such as the TSK from which arbitrar y categories were create d. Continuous measures included the Roland Morris Disabi lity Questionnaire (RMDQ), Oswe stry Disability Index (ODI), or the Quebec Back Pain Disability Scale (Q BPDS). The RMDQ (M. Roland, Morris R., 1983) is a 24-item self-report questionn aire known to have excellent re liability and validity (M. Roland & Fairbank, 2000; M. Roland, Morris R., 1983). Sc ores on the RMDQ range from 0 to 18, with higher scores reflecting greater levels of disability. The ODI is a 10-item self-report scale originally described by Fairbank and colleagues (Fairbank, 1980). Each item is scored on a five-point Likert scale with higher numbers indi cated greater disability. The QBPDS (Kopec et al.., 1996) contains 20 items that describe different activities, such as getting dressed, climbing the stairs, etc. The level of difficulty for each act ivity is expressed on a 6-point Likert scale, with higher scores indicati ng greater difficulty. In each study, the relationship of fear avoida nce to disability was assessed at baseline by examining the Pearson correlation coefficients and to obtain an estimate of the magnitude of the relationship between the variable s. Cohens conventions were then used to designate the relationship as small (.1), medium (.3) or large (.5 or greater). (Cohen, 1988).

PAGE 15

15 To examine the prospective rela tionship between fear-avoidance and disability, effect sizes were calculated or estimated based on the type of analysis conducted in each study. All studies using dichotomous outcome measures of disabili ty conducted logistic re gressions, which gave rise to odds ratios as measures of effect size. Although no st andard convention exists, it is generally accepted that an odds ratio of 1.0 to 3.0 represents a weak relationship, whereas an odds ratio over 3.0 for positive associations (or less than one-third for negative associations) indicates a moderate to strong relationship (Haddock CK, 1998). Studies in which continuous outcome measur es of disability were assessed employed a variety of regression analyses. When hierarchical linear re gressions were used and fear avoidance variables were entere d as a separate block, Cohens f2 was calculated as a measure of effect size. By convention, f2 effect sizes of 0.02, 0.15, and 0.35 are considered small, medium, and large, respectively (Cohen, 1988). One study made use of backwards stepwise regression which produced a final model that did not includ e fear-avoidance variables, and a value of zero assigned to the estimation of the effect size of f ear-avoidance. In hierarchical linear regressions where fear avoidance variables were not entered as a separate block but included with other variables, or when simultaneous regression was used, an estimate of the unique proportion of the variance explained by fear avoida nce variables was obtained by s quaring the standardized beta weights and expressed in terms of a percentage of variance expl ained. Cohens conventions of .01 for a small effect, .06 for a me dium effect, and .14 for a large e ffect were then used to assess the magnitude of the relationship. (Cohen, 1988). This convention was also applied to a third category of studies which used change in fear avoi dance measures to predic t change in disability measures.

PAGE 16

16 Table 2-1. Excluded Studies Author Year Subject population N Reason for exclusion Fritz & George 2002 Acute 782nd publication from data set George, Fritz & McNeil 2006 Acute 632nd publication from data set Klenerman et al. 1995 Acute 300Use of non-standard measure for fear-avoidance Linton & Hallden 1998 Acute, Subacute 137Mixed pain population Lotters et al. 2006 Mixed 187Mixed pain population Nederhand et al. 2004 Mixed 82Head/neck pain population Turner et al. 2006 Chronic 1,068Use of non-standard measure for fear-avoidance Vlaeyen et al. 2001 Chronic 4Fewer than ten participants Vlaeyen et al. 2002 Chronic 6Fewer than ten participants Jong et al. 2005 Chronic 6 Fewer than ten participants Jong et al. 2005 Chronic 8Fewer than ten participants

PAGE 17

17 Table 2-2. Included Studies Author Year Subject population N Length of study (months) Boersma & Linton 2006 Mixed 14112 Dionne, et al. 2006 Mixed 86024 Fritz, George & Delito 2001 Acute 691 George, et al. 2003 Acute, Subacute 666 Grotle, Vollestad & Brox 2006 Mixed 17312 Grotle, et al. 2005 Acute 1233 Mannion, et al. 2001 Chronic 1483 Picavet, Vlaeyen & Schouten 2002 Mixed 1,57 1 6 Sieben, et al. 2005 Acute 15812 Staerkle, et al. 2004 Mixed 2556 Swinkels-Meewisse, et al. 2006 Acute 431 6 Woby et al. 2004 Chronic 542

PAGE 18

18 CHAPTER 3 RESULTS Table 3-1 summarizes the correlations between fear avoidance variable s and disability at baseline. Examination of the correlations of th ese studies indicated that, with the exception of the fear-avoidance for work subsca le of the FABQ in the acute population studied by Grotle et al. (2005), fear avoidance variables were signifi cantly correlated with disability. Applying Cohens criteria, the subscale of FABQ-W in Gro tles acute population, as well as both subscales of the TSK examined in the acute population st udied by Sieben et al. (2005), yielded small correlations. Large correlations were noted by Staerkle et al. (2004) between the FABQ subscales and disability. Woby and colleagues (2 004) also noted a large correlation between the FABQ physical activity s ubscale (FA-p) and disability. The remaining studies all demonstrated moderate correlations between the fear-avoidance variables and disa bility measures at baseline. The studies were next examined to determ ine the unique effects of fear-avoidance in the prediction of disability, after c ontrolling for other relevant cl inical variables. Common covariates included variable su ch as initial disability rati ng, initial pain intensity, and demographic variables such as age and gender. A review of the statisti cal significance of fear avoidance variables in the various models predicting later disabi lity yielded mixed results for studies which used fear avoidance variables to pr edict disability. Two studies which used the total FABQ or total TSK score rather than thei r subscales as the indepe ndent variable found the fear avoidance variables to be significant predictors of disabi lity (George et al.., 2003; SwinkelsMeewisse et al.., 2006). Two studi es which used the subscales of the FABQ or TSK were unable to obtain significant results fo r any subscale (Grotle et al.., 2 006; Sieben et al.., 2005). The remaining studies, all of which used the FABQ an d TSK subscales as independent predictors of disability, found mixed significan ce. Of note is the study by Staerkle and colleagues (2004),

PAGE 19

19 which examined the FABQ subscales as predic tors of two dependent variables: perceived disability and days of work lost. The FABQ -W was found to be a significant predictor of reported days of work lost, although the FABQ-P was not. Neither subscale was significant in predicting disability as measured by the RMDQ. Overall, three of the four analyses yielded nonsignificant associations. Convers ely, in the study by Dionne et al. (2006) which examined the role of fear avoidance in predic ting disability separately for each sex, the subscales of the FABQ were independent predictors of disability, with th e only exception being th e FABQ-P in men. The two studies which used changes in fear avoida nce variables to predict changes in disability both yielded significant results. Examination of the effect sizes for the studi es which used a continuous outcome measure (including those analyzing change in disability resulting from change in fear avoidance) revealed uniformly small effects of fear avoidance variables in the models. Cohens f2 effect sizes ranged from .03 to .13, and are all considered small by C ohens conventions. If onl y significant results are considered, the effect sizes range from .03 to .10. In the five studies for which the proportion of variance explained was used as an effect size estimate, results range from 0% (when the variables were not included in the final m odel) to 6.6%. If only significant results are considered, the estimates range from 3.7% to 6.6%. Odds Ratios were used as measures of effect size in the studies which used dichotomous outcome measures. Small effect si zes were noted in the study be Fr itz et al. (Fritz et al.., 2001). Picavet and colleagues divided the TSK into tertiles, and used the middle and highest tertile as predictors of classification by the Quebec Back Pain Disability Questionnaire as disabled (Picavet et al.., 2002). Although the odds ratios are considered small, the odds ratio of the TSK, highest tertile [2.6(1.4-4 )] approaches a moderate effect si ze. Dionne and colleagues examined

PAGE 20

20 the subscales of the FABQ as predictors of a r eturn to work in good health, and examined the results by gender (Dionne et al.., 2006). The subs cale FA-P was not included in the final model for men, and resulted in a small effect size estimate for women [1.98(1.01-3.89)]. The FA-W subscale demonstrated moderate to large effects for both men [4.08(1.76-9.44)] and women [3.01(1.14-7.91)]; however, examination of the confidence intervals indi cate that the odds ratios are unstable and must be interpreted with caution. The data on statistical significan ce and effect size estimates for studies using continuous variables, dichotomous variable s, and studies measuring change are summarized in Tables 3-2, 3-3, and 3-4, respectively.

PAGE 21

21 Table 3-1. Baseline Correlations betw een Fear-Avoidance and Disability Author N Measure used Baseline correlations Boersma & Linton 141TSK Subscales .39(TSK-sf)*, .43(TSK-aa)* Dionne, et al. 369 Female 491 Male FABQ Subscales .43(FA-p)*, .49(FA-w)* .42(FA-p)*, .49(FA-w)* Fritz, George & Delito 69FABQ Subscales .34(FA-p)*, .40(FA-w)* George, et al. 66FABQ Subscales .33(FA-p)*, .42(FA-w)* Grotle, Vollestad & Brox 123 Acute 47 Chronic FABQ Subscales .34(FA-p)*, .08(FA-w) .39(FA-p)*, .34(FA-w)* Grotle, et al. 123FABQ Subscales .34(FA-p)*, .08(FA-w) Mannion, et al. 148FABQ Total Unavailable Picavet, Vlaeyen & Schouten 1,571TSK Total .33* Sieben, et al. 158TSK Subscales .16(TSK-sf)*, .28(TSK-aa)* Staerkle, et al. 255FABQ Subscales Disability: .56(FA-p)*, .57(FA-w)* Work Loss: .42(FA-p)*, .47(FA-w)* Swinkels-Meewisse, et al. 431TSK Total .398* Woby et al. 54FABQ Subscales .55(FA-p)*, .40(FA-w)* Indicates significant correlations

PAGE 22

22 Table 3-2. Significance and Effect Sizes of Studies with Continuous Variables Author N Significance Effect size estimate Boersma & Linton 141 Not retained in model (TSK-sf) p < .01 (TSK-aa) 0% (TSK-sf) 5.1% (TSK-aa) Fritz, George & Delito 69 p = .009 (FA-w) p = .083 (FA-p) .10 (FA-w) .04 (FA-p) George, et al. 66 p = .049 (FABQ total at 1 month) p = .034 (FABQ total at 6 months) .05 (FABQ) .08 (FABQ) Grotle, Vollestad & Brox 123 Acute 47 Chronic p = .23 (FA-w), p = .71 (FA-p) p = .13 (FA-w), p = .07 (FA-p) .07 (FABQ) .13 (FABQ) Sieben, et al. 158 TSK not retained in model 0% Staerkle, et al. 255 Disability: p > .05 for FABQ subscales Work Loss: p < .05(FA-w), p > .05(FA-p) .02(FABQ) .03(FABQ) SwinkelsMeewisse, et al. 431 P < .01 (TSK total) 5.2%

PAGE 23

23 Table 3-3. Significance and Effect Sizes of Studies with Dichotomous Variables Author N Significance Effect size estimate (odds ratio) Dionne, et al. 269 female 491 male p < .05 for FABQ subscales p < .05 for FA-w, FA-p not retained FA-w 3.01(1.14 7.91) FA-p 1.98(1.01 3.89) FA-w 4.08(1.76 9.44) Fritz, George & Delito 78 p = .003 (FA-w) p = .23 (FA-p) 1.17(1.04 1.31) 1.14(.96 1.34) Grotle, et al. 123 p > .05 (FA-w, high FA) p > .05 (FA-p, high FA) 1.31(.44 3.85) 1.58(.57 4.4) Picavet, Vlaeyen & Schouten 1571 p < .05 (TSK, middle tertile) p < .05 (TSK, highest tertile) 1.3(.6 2.7) 2.6(1.4 4)

PAGE 24

24 Table 3-4. Significance and Effect Size of Studies Measuring Change Author N Significance Effect size estimate (percent of variance) Mannion, et al. 143 p < .05 3.7% Woby, et al. 54 p < .05 (FA-w) p < .01 (FA-p) 4.4% 6.6%

PAGE 25

25 CHAPTER 4 DISCUSSION AND CONCLUSIONS The results of this review did not support the hypothesis that f ear-avoidance variables would be highly correlated with measures of di sability at baseline. Of the 26 correlations available for review, 20 fell within the moderately correlated range. Three high correlations and three low correlations were noted. The data provided by the studies also did not support the hypothesi s that fear-avoidance variables would demonstrat e large effects in models predicting later disability. All eight Cohens f 2 effect sizes calculated were less than .13, a nd therefore are considered small by convention (Cohen, 1988). The proportion of variance accounted for was used as an effect size estimate for five studies. The estimates ranged from 0% vari ance to 6.6%, with an average of 3.6% of the variance accounted for in the prediction of disabilit y. If only significant results are considered, the average increases to 5%. When Cohens conv entions are applied to these results, all studies demonstrate small effects, with the exception of the moderate effect size of 6.6% reported by Woby and colleagues (Woby et al.., 2004). The revi ew of the dichotomous category of studies, in which ORs were used as measures of effect size, continued to provi de evidence that fear avoidance variables demonstrate small effects in the estimation of disability. The ORs ranged from 1.14 to 4.08, with three of the four studies reviewed demonstrati ng consistently small effects (ORs less than three) The fourth study, by Dionne and colleagues (2006), contains mixed results. The effect size of the FA-P subs cale was not provided, as it was not significant. The FA-P subscale for women demonstrated an OR of 1.98, which is generally considered small. The ORs of FA-W for men and women, 4.08 a nd 3.01 respectively, could be considered moderate to large. However, the confidence inte rvals for these two ORs are quite large, a factor which indicates an unstable odds ratio, and may make these results difficult to replicate. Overall,

PAGE 26

26 although this category of study demonstrated the mo st variation, the results of the studies using dichotomous outcome measures are generally co nsistent with those of the studies using continuous outcome measures in demonstrating sma ll effect sizes for fear avoidance variables. When the results are considered together, it appears that fea r-avoidance initially correlates moderately with disability, but when relevant variables (i.e. initial pain intensity or disability, etc.) are controlled for, fear avoidance variab les cannot account for significant variance in the development and maintenance of disability from LB P. When considered within the context of the Fear Avoidance Model of Exaggerated Pain Perception and the initi al body of literature on fear avoidance and LBP, these findings are unexpect ed. It is therefore important to consider common factors which may have influenced the results of the studies. There are some indications that measurement error may have been a significant factor affecting the results in this review. Most of th e studies used the subsca les of the FABQ or TSK as independent variables. However, three of the four studies whic h obtained consistently significant results did so using the FABQ or TS K as a whole, rather than using the measure subscales. This provides prelimin ary indication that the subscales of these measures may lack the necessary stability to be reliably used in mo dels predicting disabilit y. Additionally, one third of the studies used the TSK to assess the level of fear avoidance in their sa mples. Investigations into the TSK have suggested several different factor structures, a nd indicated that the measurement properties of the TSK may be pr oblematic (Burwinkle, Robinson, & Turk, 2005; French, France, Vigneau, French, & Evans, 2007; Roelofs et al.., 2004). Ho wever, this potential problem in measurement is unlikely to provide a sufficient explanation for the small effect sizes across studies, as eight of the tw elve studies used the FABQ, but also demonstrated small effect sizes for fear-avoidance.

PAGE 27

27 A more compelling explanation of the findings can be found in examining the conceptual and statistical overlap that may occur between the construct of fear-avoidance and other psychosocial constructs, such as distress or depression. System atic reviews of the literature have consistently identified a variety of psychosocial variables as potentially important to the transition from acute to chronic pain, to include stress, mood and depression, and cognitive variables (i.e. coping style, self-efficacy) (L inton, 2000; Pincus et al.., 2002). Additionally, Pincus and colleagues found moderate effect sizes demonstrated by depression and distress in relation to a variety of outcomes, including disability (Pincus et al.., 2002). Four of the studies in the present review examined the influence of other psychosocial beliefs on the outcome of disability, either as individual predictors or in conjunction with fear-avoidance beliefs. Although no baseline correlations between fear avoidance and distre ss were provided, Grotle and colleagues, using a logistic regr ession analysis, found that, rather than fear-avoidance, distress was the best psychosocial predicto r of disability at three months and therefore did not include fear-avoidance in their final mode l (Grotle et al.., 2006). Staerk le et al. found that the FABQ subscales shared moderate baseline correlations with the Zung Depression Scale, and that depressive symptoms accounted fo r slightly more variance in th e model predicting scores on the RMDQ than did the FABQ subscales (R. sq. changes of .02 vs .01), although both variables demonstrated small effects (Staerkle et al.., 2004). Mannion and colleagues conducted a stepwise regression and found that depression and fear-avoidance beliefs accounted for 4.1% and 3.7% of the variance, respectively (Mannion et al.., 2001). Finally, Bo ersma and Linton (2006) found that, with the exception of the TSK-A su bscale and pain expectancy, the TSK subscales shared moderate correlations with pain and expectancy and negative affect, ranging from .384 .482. These variables were then entered together in a hier archical regre ssion predicting

PAGE 28

28 disability, and resulted in moderate effect size (f 2 = .17). This led them to conclude, the strong interrelationships between these variables should caution fo r treating them as separate entities. . (Boersma & Linton, 2006) This statement highlights the i ssue of the potential for shared variance between fear-avoidan ce and other psychosocial variables. Although this review followed standard recomm endations for the interpretation of effect sizes, there is a great deal of de bate about the interpretation of e ffect sizes in the psychological sciences. There are no universally accepted co nventions by which these numbers can be assigned a categorical ranking of small, medium, or large; rather, the judg ment of effect size must be considered within the context of th e dependent variable. It can be argued that questionnaire scores as a pr oxy for disability do not repres ent a clear and robust outcome measure; therefore, greater proportions of the vari ances must be accounted for to judge the effect size estimates as large. When considered within th is context, it is reasonable to conclude that the effect size estimates yielded by the proportion of the variance accounted for are small. Examination of the aggregate results also supports the conclusion that the effect size for fear avoidance variables in later disa bility is small. Although the re liability of the measures, the heterogeneity of the populations studies, and the specific levels of the variable being examined varied across studies, the effect sizes dem onstrated remained consistently small. Overall, the literature reviewed does not support the contention that fearavoidance variables play a central role in the development and maintenance of chronic LBP. However, it would be premature to conclude th at they are not related to LBP, and should not be a subject of continued investigation. Rela tive to the population suffering with LBP, the sample sizes examined in this review were small, as is the body of literature addressing this issue. Further investigation examining different populations of sufferers may id entify important interactions

PAGE 29

29 between fear avoidance variable s and population-specific factors. Additionally, this review provides preliminary support to the idea that fear-avoidance variab les may be better conceptualized and studied as part of a multidimensional psychosocial model with interrelated variables such as distress, pain catastrophizing, and negative expectancy. Because of variance shared, it is likely that consider ing these variables together, as part of a larger negative affect construct, will be better able to predict outcome s for patients with LBP. Finally, it is important to continue to investigate fear-avoidance variab les, as well as other psychosocial predictors, becausedue to the lack of biomedical explana tionspsychosocial variables represent some of the only intervention points curren tly available to patients with LBP. When compared to the options of making no intervention or to expens ive medical procedures, interventions based on fear avoidance variables may prove to be cost effective and relative ly useful, and should therefore not be ignored as a possibility which warrants continued investigation.

PAGE 30

30 LIST OF REFERENCES Al-Obaidi, S. M., Al-Zoabi, B., Al-Shuwaie, N., Al-Zaabie, N., & Nelson, R. M. (2003). The influence of pain and pain-related fear and disa bility beliefs on walking velocity in chronic low back pain. Int J Rehabil Res, 26 (2), 101-108. Andersson, H. I., Ejlertsson, G., Leden, I., & Rosenberg, C. (1993). Chronic pain in a geographically defined general population: studie s of differences in age, gender, social class, and pain localization. Clin J Pain, 9 (3), 174-182. Asmundson, G. J., Norton, G. R., & Allerdi ngs, M. D. (1997). Fear and avoidance in dysfunctional chronic back pain patients. Pain, 69 (3), 231-236. Boersma, K., & Linton, S. J. (2006) Expectancy, fear and pain in the prediction of chronic pain and disability: A pr ospective analysis. Eur J Pain, 10 (6), 551-557. Bortz, W. M., 2nd. (1984). The disuse syndrome. West J Med, 141 (5), 691-694. Burton, A. K., Tillotson, K. M., Main, C. J., & Hollis, S. (1995). Psychosocial predictors of outcome in acute and subc hronic low back trouble. Spine, 20 (6), 722-728. Burwinkle, T., Robinson, J. P., & Turk, D. C. ( 2005). Fear of movement: fa ctor structure of the tampa scale of kinesiophobia in patie nts with fibromyalgia syndrome. J Pain, 6 (6), 384391. Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed. ed.). Hillsdale, NJ: Erlbaum. Crombez, G., Vervaet, L., Lysens, R., Baeyens, F., & Eelen, P. (1998). Avoidance and confrontation of painful, back-straining m ovements in chronic back pain patients. Behav Modif, 22 (1), 62-77. Crombez, G., Vlaeyen, J. W., Heuts, P. H., & Lysens, R. (1999). Pain-related fear is more disabling than pain itself: ev idence on the role of pain-relate d fear in chronic back pain disability. Pain, 80 (1-2), 329-339. Dionne, C. E., Bourbonnais, R., Fremont, P., Rossi gnol, M., Stock, S. R., Nouwen, A., et al.. (2006). Determinants of "return to work in good health" among work ers with back pain who consult in primary care sett ings: a 2-year prospective study. Eur Spine J Fairbank, J., Couper J, Davies JB, O'Brien JP. (1 980). The Oswestry low back pain disability questionnaire. Physiotherapy, 66 271-273. Frank, J. W., Brooker, A. S., DeMaio, S. E., Ke rr, M. S., Maetzel, A., Shannon, H. S., et al.. (1996). Disability resulting from occupationa l low back pain. Part II: What do we know about secondary prevention? A review of the scientific eviden ce on prevention after disability begins. Spine, 21 (24), 2918-2929.

PAGE 31

31 French, D. J., France, C. R., Vigneau, F., French, J. A., & Evans, R. T. (2007). Fear of movement/(re)injury in chronic pain: a psychom etric assessment of the original English version of the Tampa scale for kinesiophobia (TSK). Pain, 127 (1-2), 42-51. Fritz, J. M., George, S. Z., & De litto, A. (2001). The role of fea r-avoidance beliefs in acute low back pain: relationships with current a nd future disability and work status. Pain, 94 (1), 715. Gatchel, R. J., Polatin, P. B., & Mayer, T. G. (1995). The dominant role of psychosocial risk factors in the development of ch ronic low back pain disability. Spine, 20 (24), 2702-2709. George, S. Z., Dannecker, E. A., & Robins on, M. E. (2006). Fear of pain, not pain catastrophizing, predicts acute pain intensity, but neither f actor predicts tolerance or blood pressure reactivity: an experimental i nvestigation in pain -free individuals. Eur J Pain, 10 (5), 457-465. George, S. Z., Fritz, J. M., Bialosky, J. E., & Donald, D. A. (2003). The effect of a fearavoidance-based physical thera py intervention for patients with acute low back pain: results of a randomized clinical trial. Spine, 28 (23), 2551-2560. George, S. Z., Wittmer, V. T., Fillingim, R. B., & Robinson, M. E. (2007). Sex and pain-related psychological variables are associated with th ermal pain sensitivity for patients with chronic low back pain. J Pain, 8 (1), 2-10. Goubert, L., Crombez, G., Van Damme, S., Vlaeyen, J. W., Bijttebier, P., & Roelofs, J. (2004). Confirmatory factor analysis of the Tampa Scale for Kinesiophobia: invariant two-factor model across low back pain patien ts and fibromyalgia patients. Clin J Pain, 20 (2), 103110. Grotle, M., Vollestad, N. K., & Brox, J. I. (2006). Clinical course and impact of fear-avoidance beliefs in low back pain: prospective cohort st udy of acute and chroni c low back pain: II. Spine, 31 (9), 1038-1046. Grotle, M., Vollestad, N. K., Veierod, M. B., & Brox, J. I. (2004). Fear-avoidance beliefs and distress in relation to disability in acute and chroni c low back pain. Pain, 112 (3), 343-352. Haddock CK, R. D., Shadish WR. (1998). Using Odds Ratios as Effect Sizes for Meta-Analysis of Dichotomous Data: A Primer on Methods and Issues. Psychological Methods, 3 (3), 339353. Hart, L. G., Deyo, R. A., & Cherkin, D. C. (1995) Physician office visits for low back pain. Frequency, clinical evaluation, and treatment patterns from a U.S. national survey. Spine, 20 (1), 11-19. Hestbaek, L., Leboeuf-Yde, C., & Manniche, C. (2003). Low back pain: what is the long-term course? A review of studies of general patient populations. Eur Spine J, 12 (2), 149-165.

PAGE 32

32 Klenerman, L., Slade, P. D., Stanley, I. M., Pennie, B., Reilly, J. P., Atchison, L. E., et al.. (1995). The prediction of chronicity in patients with an acute a ttack of low back pain in a general practice setting. Spine, 20 (4), 478-484. Kopec, J. A., Esdaile, J. M., Abrahamowicz, M., Abenhaim, L., Wood-Dauphinee, S., Lamping, D. L., et al.. (1996). The Quebec Back Pain Disability Scale: c onceptualization and development. J Clin Epidemiol, 49 (2), 151-161. Kottke, F. J. (1966). The effects of limitation of acitivity upon the human body. Jama, 196 (10), 825-830. Lethem, J., Slade, P. D., Troup, J. D., & Bentle y, G. (1983). Outline of a Fear-Avoidance Model of exaggerated pain perception--I. Behav Res Ther, 21 (4), 401-408. Linton, S. J. (2000). A review of psychological risk factor s in back and neck pain. Spine, 25 (9), 1148-1156. Linton, S. J., & van Tulder, M. W. (2001). Prev entive interventions for back and neck pain problems: what is the evidence? Spine, 26 (7), 778-787. Loeser, J. D. (1994). The prevention of needless pain: research opportunities. Prev Med, 23 (5), 709-711. Mannion, A. F., Junge, A., Taimela, S., Muntener M., Lorenzo, K., & Dvorak, J. (2001). Active therapy for chronic low back pain: part 3. Fact ors influencing self-rate d disability and its change following therapy. Spine, 26 (8), 920-929. Mantyselka, P., Kumpusalo, E., Ahonen, R., Kumpusalo, A., Kauhanen, J., Viinamaki, H., et al.. (2001). Pain as a reason to vi sit the doctor: a study in Fi nnish primary health care. Pain, 89 (2-3), 175-180. Mayer, T. G. (1991). Rational for Modern Spinal Care. In T. G. Mayer, Mooney V, & Gatchel RJ (Ed.), Contemporary Conservative Care for Painful Spinal Disorders (pp. 3-9). Philadelphia: Lea & Febiger. Miller RP, K. S., Todd DD. (1991). The Tampa Scale for Kinesiophobia (Unpublished Report). Picavet, H. S., Vlaeyen, J. W., & Schouten, J. S. (2002). Pain catastroph izing and kinesiophobia: predictors of chronic low back pain. Am J Epidemiol, 156 (11), 1028-1034. Pincus, T., Burton, A. K., Vogel, S., & Field, A. P. (2002). A systematic review of psychological factors as predictors of chronicity/disability in prospective cohorts of low back pain. Spine, 27 (5), E109-120. Roelofs, J., Goubert, L., Peters, M. L., Vlaeyen J. W., & Crombez, G. (2004). The Tampa Scale for Kinesiophobia: further examination of psycho metric properties in patients with chronic low back pain and fibromyalgia. Eur J Pain, 8 (5), 495-502.

PAGE 33

33 Roland, M., & Fairbank, J. (2000). The RolandMorris Disability Questionnaire and the Oswestry Disability Questionnaire. Spine, 25 (24), 3115-3124. Roland, M., Morris R. (1983). A study of the natural history of back pain. Part I: development of a reliable and sensitive measure of disability in low-back pain. Spine, 8 141-144. Schappert, S. (1989). National Ambulatory Medical Care Survey (No. Vital Health Stat 13): National Center for Health Statistics. Scheer, S. J., Radack, K. L., & O'Brien, D. R ., Jr. (1995). Randomized controlled trials in industrial low back pain re lating to return to work. Part 1. Acute interventions. Arch Phys Med Rehabil, 76 (10), 966-973. Severeijns, R., Vlaeyen, J. W., van den H out, M. A., & Weber, W. E. (2001). Pain catastrophizing predicts pain intensity, disability, and psyc hological distress independent of the level of physical impairment. Clin J Pain, 17 (2), 165-172. Sieben, J. M., Vlaeyen, J. W., Portegijs, P. J., Ve rbunt, J. A., van Riet-Rutgers, S., Kester, A. D., et al.. (2005). A longitudinal study on the pred ictive validity of the fear-avoidance model in low back pain. Pain, 117 (1-2), 162-170. Slade, P. D., Troup, J. D., Lethem, J., & Be ntley, G. (1983). The Fear-Avoidance Model of exaggerated pain perception--II. Behav Res Ther, 21 (4), 409-416. Staerkle, R., Mannion, A. F., Elfering, A., Junge A., Semmer, N. K., Jacobshagen, N., et al.. (2004). Longitudinal validation of the fear-avo idance beliefs questionn aire (FABQ) in a Swiss-German sample of low back pain patients. Eur Spine J, 13 (4), 332-340. Stang, P., Von Korff, M., & Galer, B. S. (1998). Reduced labor force participation among primary care patients with headache. J Gen Intern Med, 13 (5), 296-302. Sternbach, R. A. (1986). Pain and 'hassles' in the United States: findings of the Nuprin pain report. Pain, 27 (1), 69-80. Stewart, W. F., Ricci, J. A., Chee, E., Morg anstein, D., & Lipton, R. (2003). Lost productive time and cost due to common pain conditions in the US workforce. Jama, 290 (18), 24432454. Sullivan, M. J., Thorn, B., Haythornthwaite, J. A., Keefe, F., Martin, M., Bradley, L. A., et al.. (2001). Theoretical perspectives on the re lation between catastrophizing and pain. Clin J Pain, 17 (1), 52-64. Swinkels-Meewisse, I. E., Roelofs, J., Schoute n, E. G., Verbeek, A. L., Oostendorp, R. A., & Vlaeyen, J. W. (2006). Fear of movement/(re)i njury predicting chronic disabling low back pain: a prospective in ception cohort study. Spine, 31 (6), 658-664.

PAGE 34

34 Tacci, J. A., Webster, B. S., Hashemi, L., & Ch ristiani, D. C. (1998). Healthcare utilization and referral patterns in the initial management of new-onset, uncomplicated, low back workers' compensation disability claims. J Occup Environ Med, 40 (11), 958-963. Turk, D., Melzack R. (2001). The measurement of pain and the assessment of people experiencing pain. In D. C. Turk, Melzack R. (Ed.), Handbook of pain assessment (2nd ed. ed.). New York: Guilford. Vlaeyen, J. W., Kole-Snijders, A. M., Boer en, R. G., & van Eek, H. (1995). Fear of movement/(re)injury in chronic low back pain and its relation to behavioral performance. Pain, 62 (3), 363-372. Vlaeyen, J. W., & Linton, S. J. (2000). Fear-a voidance and its conse quences in chronic musculoskeletal pain: a state of the art. Pain, 85 (3), 317-332. Waddell, G., Newton, M., Henderson, I., Somerville, D., & Main, C. J. (1993). A FearAvoidance Beliefs Questionnaire (FABQ) and the role of fear-avoidance beliefs in chronic low back pain and disability. Pain, 52 (2), 157-168. Walker, B. F., Muller, R., & Grant, W. D. (2004). Low back pain in Australian adults: prevalence and associated disability. J Manipulative Physiol Ther, 27 (4), 238-244. Watson, P. J., Main, C. J., Waddell, G., Gales, T. F., & Purcell-Jones, G. (1998). Medically certified work loss, recurrence and costs of wage compensation for back pain: a follow-up study of the working population of Jersey. Br J Rheumatol, 37 (1), 82-86. Woby, S. R., Watson, P. J., Roach, N. K., & Urms ton, M. (2004). Are changes in fear-avoidance beliefs, catastrophizing, and appr aisals of control, predictive of changes in chronic low back pain and disability? Eur J Pain, 8 (3), 201-210.

PAGE 35

35 BIOGRAPHICAL SKETCH Alisa Diane Hassinger was born on May 21, 1973 in Harrisburg, Pennsylvania. The youngest of two, she grew up in the greater Harri sburg area, graduating from Millersburg Area High School in 1991. She earned her B.A. in psychology from Indiana University of Pennsylvania. Upon graduating with honors in 1995, she began graduate studi es in social work at Arizona State University. Alisa graduated with Master of Social Work in 1997, and subsequently accepted a commission to serve in the United States Army as a social work officer. Upon her honorable discharge from the military in 2003, Alisa continued to work for the Department of Defense at Fort Benning, Georgia as a case manager and th erapist for soldiers with deployment related mental health concerns. Alisa relocated to Gainesville, Florida in August of 2005 to begin her graduate career in clinical psychology. Upon completion of the M.S., Alisa will continue on in her program and apply for doctoral candidacy in the Department of Clinical and Health Psychology at the University of Florida.


Permanent Link: http://ufdc.ufl.edu/UFE0020112/00001

Material Information

Title: The Relationship of Fear-Avoidance to Disability: A Quantitative Review
Physical Description: Mixed Material
Copyright Date: 2008

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0020112:00001

Permanent Link: http://ufdc.ufl.edu/UFE0020112/00001

Material Information

Title: The Relationship of Fear-Avoidance to Disability: A Quantitative Review
Physical Description: Mixed Material
Copyright Date: 2008

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0020112:00001


This item has the following downloads:


Full Text





THE RELATIONSHIP OF FEAR-AVOIDANCE TO DISABILITY:
A QUANTITATIVE REVIEW





















By

ALISA DIANE HASSINGER


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2007

































O 2007 Alisa Diane Hassinger









ACKNOWLEDGMENTS

I thank my supervisory committee chair, Dr. Michael Robinson, for his invaluable

guidance and mentoring. I would also like to thank the members of the Center for Pain Research

for their help and support.












TABLE OF CONTENTS


page

ACKNOWLEDGMENTS .............. ...............3.....


LIST OF TABLES .........__.. ..... .__. ...............5....


AB S TRAC T ......_ ................. ............_........6


CHAPTER


1 INTRODUCTION ................. ...............7.......... ......


Chronic Low Back Pain: A Statement of the Problem ................ ............... ......... ...7
The Fear-Avoidance Model of Exaggerated Pain Perception ................. ................ ...._.8

2 M ETHODS ................. ...............12.......... .....


3 RE SULT S ................. ...............18.......... .....


4 DISCUS SION AND CONCLUSIONS .............. ...............25....


LIST OF REFERENCES ................. ...............30................


BIOGRAPHICAL SKETCH .............. ...............35....










LIST OF TABLES


Table Page

2-1 Excluded Studies............... ...............16

2-2 Included Studies............... ...............17

3-1 Baseline Correlations between Fear-Avoidance and Disability .............. ...................21

3-2 Significance and Effect Sizes of Studies with Continuous Variables............... ...............22

3-3 Significance and Effect Sizes of Studies with Dichotomous Variables ............................23

3-4 Significance and Effect Size of Studies Measuring Change ................. ......................24









Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

THE RELATIONSHIPS OF FEAR-AVOIDANCE TO DISABILITY: A QUANTITATIVE
REVIEW

By

Alisa Diane Hassinger

May 2007

Chair: Michael Robinson
Major: Psychology

Pain-related fear and its attendant avoidance behaviors have been identified as key

psychosocial variables in the development and maintenance of chronic low back pain. A

growing number of prospective studies have indicated that fear-avoidance models are useful in

predicting long-term disability. However, longitudinal data have yielded varying and sometimes

conflicting results. A systematic quantitative review of prospective studies was conducted to

examine the effect sizes of fear avoidance variables in the prediction of disability in patients with

low back pain. A literature search resulted in 12 studies which met initial inclusion criteria.

Analyses revealed that while fear avoidance variables typically share moderate zero order

correlations with disability measured at baseline, effect sizes decrease to small effects over time,

particularly when controlling for relevant variables such as initial pain intensity, or psychosocial

variables such as distress. This pattern of results indicates that fear avoidance variables may

share substantial statistical and conceptual overlap with other psychosocial variables and may be

best viewed as part of a larger psychosocial model, rather than as independent predictors of

disability.









CHAPTER 1
INTTRODUCTION

Chronic Low Back Pain: A Statement of the Problem

Pain is one of the most common reasons people seek medical attention (Schappert, 1989).

When pain becomes chronic, there are serious negative consequences for physical,

psychological, and social functioning, with deleterious effects noted in both work and family life

(Turk, 2001).

Low Back Pain (LBP) is one of the most common forms of pain reported (Mantyselka et

al.., 2001; Sternbach, 1986), with 53% of adults in the general population experiencing some

disability from LBP in a six month period (Walker, Muller, & Grant, 2004). LBP is a significant

source of cost to both the individual and society, associated with increased healthcare

expenditures and lost productivity (Andersson, Ejlertsson, Leden, & Rosenberg, 1993; Stang,

Von Korff, & Galer, 1998; Stewart, Ricci, Chee, Morganstein, & Lipton, 2003; Tacci, Webster,

Hashemi, & Christiani, 1998; Walker et al.., 2004). It has long been asserted that only a small

percentage of patients who experience an acute episode will develop chronic LBP (Watson,

Main, Waddell, Gales, & Purcell-Jones, 1998). However, recent data suggests that acute LBP

evolves into a chronic or recurrent condition more frequently than previously suspected

(Hestback, Leboeuf-Yde, & Manniche, 2003).

Chronic LBP, with an estimated prevalence of 15 tol8% in the adult population, is of

special concern (Frank et al.., 1996). The cost of chronic LBP to society has been estimated at

$18 billion annually (Linton & van Tulder, 2001), a figure which distinguishes chronic LBP as

the most expensive benign medical condition in industrialized countries (Mayer, 1991). The

associated prevalence and costs highlight chronic LBP as an important public health concern,









and underscore the need for research focused on the identification and treatment of those at risk

for developing chronic LBP.

Because an underlying physical pathology responsible for the development and

maintenance of chronic LBP has not been discovered in the majority of patients who suffer with

this condition, the development of biomedically oriented prevention and treatment strategies has

not been successful (Hart, Deyo, & Cherkin, 1995; Linton & van Tulder, 2001; Loeser, 1994).

Randomized, clinical trials have repeatedly shown that commonly used strategies intended to

prevent the development of LBP, such as back schools, lumbar supports, and ergonomic

interventions, are ineffective (Linton & van Tulder, 2001; Scheer, Radack, & O'Brien, 1995).

However, studies have consistently identified psychosocial factors rather than physical

impairments as better predictors of which patients will develop chronic disability from an acute

episode of LBP (Burton, Tillotson, Main, & Hollis, 1995; Frank et al.., 1996; Gatchel, Polatin, &

Mayer, 1995; Pincus, Burton, Vogel, & Field, 2002)

The Fear-Avoidance Model of Exaggerated Pain Perception

The Fear-avoidance Model of Exaggerated Pain Perception (FAMEPP), first proposed by

Lethem and colleagues in 1983, has been posited as one explanation for why a subgroup of

patients develop chronic LBP and its attendant disability (Lethem, Slade, Troup, & Bentley,

1983; Slade, Troup, Lethem, & Bentley, 1983). This model proposes that fear-avoidance beliefs

and pain catastrophizing are the primary psychosocial factors responsible for the development of

chronic LBP symptoms. More specifically, a patient's response to LBP can fall along a

continuum of confrontation to avoidance. A confrontation response is viewed as adaptive as it

supports the patient's participation in daily social and vocational activities, encouraging a

recovery of function. An avoidance response to pain results from higher levels of pain related

fear and avoidance, and has negative psychological and physical consequences for the individual.










Psychologically, exaggerated pain perception results from elevated levels of fear (George,

Dannecker, & Robinson, 2006; George, Wittmer, Fillingim, & Robinson, 2007). Patients also

may develop depressive and anxious symptoms as a result of their perceived loss of function,

factors which are known to be associated with decreased pain tolerance (Vlaeyen & Linton,

2000). Physically, patients with LBP experience "disuse syndrome" (decreased spine range of

motion, loss of muscle force, and weight gain) as a result of their avoidant response to the fear of

pain (Bortz, 1984; Kottke, 1966; Lethem et al.., 1983; Slade et al.., 1983). A continuous

feedback loop is therefore created in which the patient's elevated fear results in avoidant

behavior, which consequently leads to increasing disability, emotional distress, and the

maintenance of the fear and avoidance.

Vlaeyen and colleagues have further elaborated on this model by proposing a Cognitive

Model of Fear of Movement/(Re)injury (Vlaeyen, Kole-Snijders, Boeren, & van Eek, 1995).

This model conceptualized the pain related fear as a specific fear of movement, particularly that

which the patient believes may result in further injury. This model also highlights the role of

pain catastrophizing, defined as the belief that the pain experience will lead to the worst possible

outcome (Sullivan et al.., 2001), as a psychosocial variable which increases the patient' s fear of

movement and subsequent avoidance behaviors (Vlaeyen & Linton, 2000).

Initial investigations have consistently demonstrated that elevated levels of pain related

fear and avoidance are associated with the development and maintenance of chronic low back

pain and its attendant disability. A study by Crombez and colleagues in 1998 categorized

subj ects as having either a confrontational or avoidance coping style, and found that those

classified as Avoiders had greater pain related fear and levels of disability, and more difficulty

with physical activities (Crombez, Vervaet, Lysens, Baeyens, & Eelen, 1998). Further evidence









of the relationship of pain related fear and functional limitations has been found in studies

investigating the performances of patients with CLBP during a task which measured walking

speed (Al-Obaidi, Al-Zoabi, Al-Shuwaie, Al-Zaabie, & Nelson, 2003) and a lifting task (Vlaeyen

et al.., 1995). A growing body of literature exists which has demonstrated a relationship

between higher levels of fear-avoidance and greater levels of disability (Asmundson, Norton, &

Allerdings, 1997; Crombez, Vlaeyen, Heuts, & Lysens, 1999; Severeijns, Vlaeyen, van den

Hout, & Weber, 2001; Waddell, Newton, Henderson, Somerville, & Main, 1993).

However, much of the research performed has been, until recently, cross sectional in

nature, and thus unable to establish a causal relationship between elevated pain related fear and

the development of chronic LBP disability. In 1995, Klenerman and colleagues published the

first prospective study examining the relationship between these variables, and found higher

levels of pain related fear to be a significant contributor to chronic LBP disability (Klenerman et

al.., 1995). Many of the prospective studies which followed also found this relationship

(Boersma & Linton, 2006; Fritz, George, & Delitto, 2001; George, Fritz, Bialosky, & Donald,

2003; Picavet, Vlaeyen, & Schouten, 2002; Woby, Watson, Roach, & Urmston, 2004).

However; the results of these studies were more mixed than those of the cross sectional

examinations. Several studies were unable to find significant prospective relationships between

pain related fear, and disability (Grotle, Vollestad, & Brox, 2006; Grotle, Vollestad, Veierod, &

Brox, 2004; Sieben et al.., 2005; Staerkle et al.., 2004).

Aims and Hypotheses

Although it appears that both cross sectional and prospective studies have indicated that

fear-avoidance beliefs may play a role in the development of chronic LBP disability, the

magnitude of these effects has not been systematically examined in the literature. With a









growing body of prospective literature, it is an opportune time to investigate the strength of the

relationship between fear-avoidance beliefs and disability in order to guide future research

endeavors. Our study proposes a quantitative review of the prospective literature to examine the

relationship between fear avoidance variables measured at baseline and a follow-up time point,

with the intention of assessing the magnitude of the relationship between pain related fear and

disability.

The first aim of our study was to examine the relationship of fear-avoidance variables to

initial disability ratings in patients with LBP. We hypothesize that fear-avoidance variables will

be highly correlated with measures of disability.

The second aim is too assess the effectiveness of the fear-avoidance model in predicting

later disability in patients with LBP. We hypothesize that fear-avoidance variables will

demonstrate large effect sizes in models predicting later LBP related disability.









CHAPTER 2
METHOD S

A review of the literature was undertaken to identify prospective studies using Fear-

avoidance Beliefs as an independent variable predicting a measure of disability. A Medline

database search was conducted using the following search terms: Pain, Fear-avoidance; Pain,

Kinesiophobia; Pain, Fear of Movement/(Re)Injury. A publication cutoff date of September,

2006, was used; however, no backward cutoff date was specified. Additional articles were

identified using the bibliographies of the studies located through Medline database.

Twenty-Hyve studies were initially identified for inclusion in the review. Because this is a

small but increasing body of research available with a relatively new construct, liberal exclusion

criteria were developed. The first exclusion criterion precluded the inclusion of multiple studies

which used the same data set. When these studies were identified, only the first study published

using the data was included. This resulted in the exclusion of two studies. An exception to this

criterion was made for the two studies conducted by Grotle et al.., as the second study added an

additional population and used a different method of analysis.

The second exclusion criterion required that studies use standardized instruments to

measure Fear-avoidance Beliefs and Disability in order to be included in the review. Studies

with non-standardized instruments were permitted if they provided pilot data for the measure

they selected. Two studies were excluded for the use of non-standard measures. Because the

great maj ority of the literature has addressed only back pain, the use of a mixed pain population

was the third basis for exclusion, disqualifying three studies. The fourth criterion required that

studies use a sample size of 10 or more subj ects. This resulted in the exclusion of four studies

with sample sizes of four, six, six, and eight. After exclusion criteria were applied, 14 studies

were eligible for inclusion. A summary of the excluded studies can be found in Table 2-1.










Analyses were planned to examine the correlations between fear-avoidance variables at

baseline, and to calculate effect size estimates in order to examine the strength of the relationship

between the fear-avoidance variables and measures of disability after a period of time. Of the 14

eligible studies, two were deemed to contain sufficient data at publication to allow for the

strength of the relationship between fear-avoidance and disability to be examined at both

baseline and follow-up. Therefore, twelve e-mail requests were made to corresponding authors

to obtain the additional data required for the planned analyses. Of the twelve requests, one

author could not be reached, and two authors did not respond. However, one of these articles

contained enough information for one of the two planned analyses, and therefore was included.

In total, twelve articles were included in the final review, with ten studies examining fear-

avoidance variables as predictors of disability and two studies using an observed change in fear-

avoidance variables as predictors of change in disability.

The studies reviewed included both acute and chronic pain populations recruited from a

variety of settings, including primary care clinics, pain clinics, and general population surveys.

The number of subj ects included in the studies ranged from 54 to 1,571. Subj ects were followed

for time periods ranging from one month to two years. A summary of included studies can be

found in Table 2-2.

All studies measured the independent variable of pain related fear by the administration

of one of two standard self-report questionnaires: the Fear-avoidance Beliefs Questionnaire

(FABQ) or the Tampa Scale ofKinesiophobia (TSK). The Fear-avoidance Beliefs Questionnaire

(FABQ) is a measure described by Waddell and colleagues (Waddell et al.., 1993). It contains

16 items, each scored on a 6-point Likert scale with higher numbers indicating increased levels

of fear-avoidance beliefs. Two subscales have been identified within the FABQ: a seven-item









work subscale and a four-item physical activity subscale. The TSK (Miller RP, 1991) is a 17

item self report questionnaire with items scored on a 4-point Likert scale. Recent investigations

have indicated that the TSK can be divided into two subscale which describe the contracts of

somatic focus (five items) and activity avoidance (eight items)(Goubert et al.., 2004; Roelofs,

Goubert, Peters, Vlaeyen, & Crombez, 2004).

The dependent variable of disability was measured using a variety of methods, both

dichotomous and continuous. Dichotomous measures included work status, and self report

measures such as the TSK from which arbitrary categories were created. Continuous measures

included the Roland Morris Disability Questionnaire (RMDQ), Oswestry Disability Index (ODI),

or the Quebec Back Pain Disability Scale (QBPDS). The RMDQ (M. Roland, Morris R., 1983)

is a 24-item self-report questionnaire known to have excellent reliability and validity (M. Roland

& Fairbank, 2000; M. Roland, Morris R., 1983). Scores on the RMDQ range from 0 to 18, with

higher scores reflecting greater levels of disability. The ODI is a 10-item self-report scale

originally described by Fairbank and colleagues (Fairbank, 1980). Each item is scored on a

five-point Likert scale with higher numbers indicated greater disability. The QBPDS (Kopec et

al.., 1996) contains 20 items that describe different activities, such as getting dressed, climbing

the stairs, etc. The level of difficulty for each activity is expressed on a 6-point Likert scale, with

higher scores indicating greater difficulty.

In each study, the relationship of fear avoidance to disability was assessed at baseline by

examining the Pearson correlation coefficients and to obtain an estimate of the magnitude of the

relationship between the variables. Cohen's conventions were then used to designate the

relationship as small (. 1), medium (.3) or large (.5 or greater). (Cohen, 1988).










To examine the prospective relationship between fear-avoidance and disability, effect sizes

were calculated or estimated based on the type of analysis conducted in each study. All studies

using dichotomous outcome measures of disability conducted logistic regressions, which gave

rise to odds ratios as measures of effect size. Although no standard convention exists, it is

generally accepted that an odds ratio of 1.0 to 3.0 represents a weak relationship, whereas an

odds ratio over 3.0 for positive associations (or less than one-third for negative associations)

indicates a moderate to strong relationship (Haddock CK, 1998).

Studies in which continuous outcome measures of disability were assessed employed a

variety of regression analyses. When hierarchical linear regressions were used and fear

avoidance variables were entered as a separate block, Cohen's ? was calculated as a measure of

effect size. By convention, P effect sizes of 0.02, 0. 15, and 0.35 are considered small, medium,

and large, respectively (Cohen, 1988). One study made use of backwards stepwise regression

which produced a final model that did not include fear-avoidance variables, and a value of zero

assigned to the estimation of the effect size of fear-avoidance. In hierarchical linear regressions

where fear avoidance variables were not entered as a separate block but included with other

variables, or when simultaneous regression was used, an estimate of the unique proportion of the

variance explained by fear avoidance variables was obtained by squaring the standardized beta

weights and expressed in terms of a percentage of variance explained. Cohen's conventions of

.01 for a small effect, .06 for a medium effect, and .14 for a large effect were then used to assess

the magnitude of the relationship. (Cohen, 1988). This convention was also applied to a third

category of studies which used change in fear avoidance measures to predict change in disability

measures.














Table 2-1. Excluded Studies


Subj ect
population
Acute
Acute
Acute


Author
Fritz & George
George, Fritz & McNeil
Klenerman et al.

Linton & Hallden

Letters et al.
Nederhand et al.
Turner et al.


N Reason for exclusion
78 2nd publication from data set
63 2nd publication from data set
300 Use of non-standard measure for
fear-avoidance
137 Mixed pain population


Year
2002
2006
1995


1998 Acute,
Subacute
2006 Mixed
2004 Mixed
2006 Chronic


187
82
1,068


Mixed pain population
Head/neck pain population
Use of non-standard measure for
fear-avoidance
Fewer than ten participants
Fewer than ten participants
Fewer than ten participants
Fewer than ten participants


Vlaeyen et al.
Vlaeyen et al.
Jong et al.
Jong et al.


2001
2002
2005
2005


Chronic
Chronic
Chronic
Chronic

























158
255
431
54


Table 2-2. Included Studies


Length of study
(months)


Subj ect
population
Mixed
Mixed
Acute
Acute,
Subacute
Mixed
Acute
Chronic
Mixed

Acute
Mixed
Acute
Chronic


Author
Boersma & Linton
Dionne, et al.
Fritz, George & Delito
George, et al.

Grotle, Vollestad & Brox
Grotle, et al.
Mannion, et al.
Picavet, Vlaeyen &
Schouten
Sieben, et al.
Staerkle, et al.
Swinkels-Meewisse, et al.
Woby et al.


Year
2006
2006
2001
2003

2006
2005
2001
2002

2005
2004
2006
2004


N
141
860
69
66

173
123
148
1,57









CHAPTER 3
RESULTS

Table 3-1 summarizes the correlations between fear avoidance variables and disability at

baseline. Examination of the correlations of these studies indicated that, with the exception of

the fear-avoidance for work subscale of the FABQ in the acute population studied by Grotle et

al. (2005), fear avoidance variables were significantly correlated with disability. Applying

Cohen' s criteria, the subscale of FABQ-W in Grotle' s acute population, as well as both subscales

of the TSK examined in the acute population studied by Sieben et al. (2005), yielded small

correlations. Large correlations were noted by Staerkle et al. (2004) between the FABQ

sub scales and disability. Woby and colleagues (2004) also noted a large correlation between the

FABQ physical activity subscale (FA-p) and disability. The remaining studies all demonstrated

moderate correlations between the fear-avoidance variables and disability measures at baseline.

The studies were next examined to determine the unique effects of fear-avoidance in the

prediction of disability, after controlling for other relevant clinical variables. Common

covariates included variable such as initial disability rating, initial pain intensity, and

demographic variables such as age and gender. A review of the statistical significance of fear

avoidance variables in the various models predicting later disability yielded mixed results for

studies which used fear avoidance variables to predict disability. Two studies which used the

total FABQ or total TSK score rather than their subscales as the independent variable found the

fear avoidance variables to be significant predictors of disability (George et al.., 2003; Swinkels-

Meewisse et al.., 2006). Two studies which used the subscales of the FABQ or TSK were unable

to obtain significant results for any subscale (Grotle et al.., 2006; Sieben et al.., 2005). The

remaining studies, all of which used the FABQ and TSK subscales as independent predictors of

disability, found mixed significance. Of note is the study by Staerkle and colleagues (2004),









which examined the FABQ subscales as predictors of two dependent variables: perceived

disability and days of work lost. The FABQ-W was found to be a significant predictor of

reported days of work lost, although the FABQ-P was not. Neither subscale was significant in

predicting disability as measured by the RMDQ. Overall, three of the four analyses yielded non-

significant associations. Conversely, in the study by Dionne et al. (2006) which examined the

role of fear avoidance in predicting disability separately for each sex, the subscales of the FABQ

were independent predictors of disability, with the only exception being the FABQ-P in men.

The two studies which used changes in fear avoidance variables to predict changes in disability

both yielded significant results.

Examination of the effect sizes for the studies which used a continuous outcome measure

(including those analyzing change in disability resulting from change in fear avoidance) revealed

uniformly small effects of fear avoidance variables in the models. Cohen's ? effect sizes ranged

from .03 to .13, and are all considered small by Cohen's conventions. If only significant results

are considered, the effect sizes range from .03 to .10. In the five studies for which the proportion

of variance explained was used as an effect size estimate, results range from 0% (when the

variables were not included in the final model) to 6.6%. If only significant results are

considered, the estimates range from 3.7% to 6.6%.

Odds Ratios were used as measures of effect size in the studies which used dichotomous

outcome measures. Small effect sizes were noted in the study be Fritz et al. (Fritz et al.., 2001).

Picavet and colleagues divided the TSK into tertiles, and used the middle and highest tertile as

predictors of classification by the Quebec Back Pain Disability Questionnaire as disabled

(Picavet et al.., 2002). Although the odds ratios are considered small, the odds ratio of the TSK,

highest tertile [2.6(1.4-4)] approaches a moderate effect size. Dionne and colleagues examined









the subscales of the FABQ as predictors of a "return to work in good health," and examined the

results by gender (Dionne et al.., 2006). The subscale FA-P was not included in the final model

for men, and resulted in a small effect size estimate for women [1.98(1.01-3.89)]. The FA-W

subscale demonstrated moderate to large effects for both men [4.08(1.76-9.44)] and women

[3.01(1.14-7.9 1)]; however, examination of the confidence intervals indicate that the odds ratios

are unstable and must be interpreted with caution.

The data on statistical significance and effect size estimates for studies using continuous

variables, dichotomous variables, and studies measuring change are summarized in Tables 3-2,

3-3, and 3-4, respectively.















Table 3-1. Baseline Correlations between Fear-Avoidance and Disability


Baseline
correlations
.39(TSK-sf)*, .43(TSK-aa)*
.43(FA-p)*, .49(FA-w)*
.42(FA-p)*, .49(FA-w)*
.34(FA-p)*, .40(FA-w)*

.33(FA-p)*, .42(FA-w)*

.34(FA-p)*, .08(FA-w)
.39(FA-p)*, .34(FA-w)*
.34(FA-p)*, .08(FA-w)

Unavailable
.33*

.16(TSK-sf)*, .28(TSK-aa)*
Disability: .56(FA-p)*, .57(FA-w)*
Work Loss: .42(FA-p)*, .47(FA-w)*
.398*

.55(FA-p)*, .40(FA-w)*


Author
Boersma & Linton
Dionne, et al.

Fritz, George & Delito


Measure used
41 TSK Subscales
ale FABQ
ale Subscales
69 FABQ
Subscales
66 FABQ
Subscales
ute FABQ
nic Subscales
23 FABQ
Subscales
48 FABQ Total
;71 TSK Total


1
369 Fem;
491 M;


George, et al.


Grotle, Vollestad &
Brox
Grotle, et al.

Mannion, et al.
Picavet, Vlaeyen &
Schouten
Sieben, et al.
Staerkle, et al.

Swinkels-Meewisse, et
al.
Woby et al.


123 Act
47 Chrol
1


15


158 TSK Subscales
255 FABQ
Subscales
431 TSK Total

54 FABQ
Subscales


* Indicates significant correlations












Table 3-2. Significance and Effect Sizes of Studies with Continuous Variables
Effect size
Author N Significance estimate
Boersma & Linton 141 Not retained in model (TSK-sf) 0% (TSK-sf)
p <.01 (TSK-aa) 5.1% (TSK-aa)
Fritz, George & 69 p = .009 (FA-w) .10 (FA-w)
Delito p =.083 (FA-p) .04 (FA-p)
George, et al. 66 p = .049 (FABQ total at 1 month) .05 (FABQ)
p = .034 (FABQ total at 6 months) .08 (FABQ)
Grotle, Vollestad 123 Acute p = .23 (FA-w), p = .71 (FA-p) .07 (FABQ)
& Brox 47 Chronic p = .13 (FA-w), p = .07 (FA-p) .13 (FABQ)
Sieben, et al. 158 TSK not retained in model 0%
Staerkle, et al. 255 Disability: p > .05 for FABQ subscales .02(FABQ)
Work Loss: p < .05(FA-w), p > .05(FA-p) .03(FABQ)
Swinkels- 431 P < .01 (TSK total) 5.2%
Meewisse, et al.










Table 3-3. Significance and Effect Sizes of Studies with Dichotomous Variables
Effect size estimate
Author N Significance (odds ratio)
Dionne, et al. 269 female p <.05 for FABQ subscales FA-w 3.01(1.14 7.91)
FA-p 1.98(1.01 -3.89)
491 male p < .05 for FA-w, FA-p not retained FA-w 4.08(1.76 9.44)
Fritz, George & 78 p = .003 (FA-w) 1.17(1.04 1.31)
Delito p = .23 (FA-p) 1.14(.96 1.34)
Grotle, et al. 123 p > .05 (FA-w, high FA) 1.31(.44 3.85)
p > .05 (FA-p, high FA) 1.58(.57 4.4)
Picavet, Vlaeyen 1571 p < .05 (TSK, middle tertile) 1.3(.6 2.7)
& Schouten p < .05 (TSK, highest tertile) 2.6(1.4 4)










Table 3-4. Significance and Effect Size of Studies Measuring Change
Author N Significance Effect size estimate
(percent of variance)
Mannion, et al. 143 p <.05 3.7%
Woby, et al. 54 p <.05 (FA-w) 4.4%
p <.01 (FA-p) 6.6%









CHAPTER 4
DISCUSSION AND CONCLUSIONS

The results of this review did not support the hypothesis that fear-avoidance variables

would be highly correlated with measures of disability at baseline. Of the 26 correlations

available for review, 20 fell within the moderately correlated range. Three high correlations and

three low correlations were noted.

The data provided by the studies also did not support the hypothesis that fear-avoidance

variables would demonstrate large effects in models predicting later disability. All eight Cohen's

f 2 effect sizes calculated were less than .13, and therefore are considered small by convention

(Cohen, 1988). The proportion of variance accounted for was used as an effect size estimate for

five studies. The estimates ranged from 0% variance to 6.6%, with an average of 3.6% of the

variance accounted for in the prediction of disability. If only significant results are considered,

the average increases to 5%. When Cohen's conventions are applied to these results, all studies

demonstrate small effects, with the exception of the moderate effect size of 6.6% reported by

Woby and colleagues (Woby et al.., 2004). The review of the dichotomous category of studies,

in which ORs were used as measures of effect size, continued to provide evidence that fear

avoidance variables demonstrate small effects in the estimation of disability. The ORs ranged

from 1.14 to 4.08, with three of the four studies reviewed demonstrating consistently small

effects (ORs less than three). The fourth study, by Dionne and colleagues (2006), contains

mixed results. The effect size of the FA-P subscale was not provided, as it was not significant.

The FA-P subscale for women demonstrated an OR of 1.98, which is generally considered small.

The ORs of FA-W for men and women, 4.08 and 3.01 respectively, could be considered

moderate to large. However, the confidence intervals for these two ORs are quite large, a factor

which indicates an unstable odds ratio, and may make these results difficult to replicate. Overall,









although this category of study demonstrated the most variation, the results of the studies using

dichotomous outcome measures are generally consistent with those of the studies using

continuous outcome measures in demonstrating small effect sizes for fear avoidance variables.

When the results are considered together, it appears that fear-avoidance initially correlates

moderately with disability, but when relevant variables (i.e. initial pain intensity or disability,

etc.) are controlled for, fear avoidance variables cannot account for significant variance in the

development and maintenance of disability from LBP. When considered within the context of

the Fear Avoidance Model of Exaggerated Pain Perception and the initial body of literature on

fear avoidance and LBP, these findings are unexpected. It is therefore important to consider

common factors which may have influenced the results of the studies.

There are some indications that measurement error may have been a significant factor

affecting the results in this review. Most of the studies used the subscales of the FABQ or TSK

as independent variables. However, three of the four studies which obtained consistently

significant results did so using the FABQ or TSK as a whole, rather than using the measure

subscales. This provides preliminary indication that the subscales of these measures may lack

the necessary stability to be reliably used in models predicting disability. Additionally, one third

of the studies used the TSK to assess the level of fear avoidance in their samples. Investigations

into the TSK have suggested several different factor structures, and indicated that the

measurement properties of the TSK may be problematic (Burwinkle, Robinson, & Turk, 2005;

French, France, Vigneau, French, & Evans, 2007; Roelofs et al.., 2004). However, this potential

problem in measurement is unlikely to provide a sufficient explanation for the small effect sizes

across studies, as eight of the twelve studies used the FABQ, but also demonstrated small effect

sizes for fear-avoidance.









A more compelling explanation of the Eindings can be found in examining the conceptual

and statistical overlap that may occur between the construct of fear-avoidance and other

psychosocial constructs, such as distress or depression. Systematic reviews of the literature

have consistently identified a variety of psychosocial variables as potentially important to the

transition from acute to chronic pain, to include stress, mood and depression, and cognitive

variables (i.e. coping style, self-efficacy) (Linton, 2000; Pincus et al.., 2002). Additionally,

Pincus and colleagues found moderate effect sizes demonstrated by depression and distress in

relation to a variety of outcomes, including disability (Pincus et al.., 2002). Four of the studies in

the present review examined the influence of other psychosocial beliefs on the outcome of

disability, either as individual predictors or in conjunction with fear-avoidance beliefs. Although

no baseline correlations between fear avoidance and distress were provided, Grotle and

colleagues, using a logistic regression analysis, found that, rather than fear-avoidance, distress

was the best psychosocial predictor of disability at three months, and therefore did not include

fear-avoidance in their Einal model (Grotle et al.., 2006). Staerkle et al. found that the FABQ

subscales shared moderate baseline correlations with the Zung Depression Scale, and that

depressive symptoms accounted for slightly more variance in the model predicting scores on the

RMDQ than did the FABQ subscales (R. sq. changes of .02 vs .01), although both variables

demonstrated small effects (Staerkle et al.., 2004). Mannion and colleagues conducted a

stepwise regression and found that depression and fear-avoidance beliefs accounted for 4. 1% and

3.7% of the variance, respectively (Mannion et al.., 2001). Finally, Boersma and Linton (2006)

found that, with the exception of the TSK-A subscale and pain expectancy, the TSK subscales

shared moderate correlations with pain and expectancy and negative affect, ranging from .384 -

.482. These variables were then entered together in a hierarchical regression predicting









disability, and resulted in moderate effect size (f 2 = .17). This led them to conclude, ... the

strong interrelationships between these variables should caution for treating them as separate

entities. ." (Boersma & Linton, 2006) This statement highlights the issue of the potential for

shared variance between fear-avoidance and other psychosocial variables.

Although this review followed standard recommendations for the interpretation of effect

sizes, there is a great deal of debate about the interpretation of effect sizes in the psychological

sciences. There are no universally accepted conventions by which these numbers can be

assigned a categorical ranking of small, medium, or large; rather, the judgment of effect size

must be considered within the context of the dependent variable. It can be argued that

questionnaire scores as a proxy for disability do not represent a clear and robust outcome

measure; therefore, greater proportions of the variances must be accounted for to judge the effect

size estimates as large. When considered within this context, it is reasonable to conclude that the

effect size estimates yielded by the proportion of the variance accounted for are small.

Examination of the aggregate results also supports the conclusion that the effect size for fear

avoidance variables in later disability is small. Although the reliability of the measures, the

heterogeneity of the populations studies, and the specific levels of the variable being examined

varied across studies, the effect sizes demonstrated remained consistently small.

Overall, the literature reviewed does not support the contention that fear- avoidance

variables play a central role in the development and maintenance of chronic LBP. However, it

would be premature to conclude that they are not related to LBP, and should not be a subj ect of

continued investigation. Relative to the population suffering with LBP, the sample sizes

examined in this review were small, as is the body of literature addressing this issue. Further

investigation examining different populations of sufferers may identify important interactions









between fear avoidance variables and population-specific factors. Additionally, this review

provides preliminary support to the idea that fear-avoidance variables may be better

conceptualized and studied as part of a multidimensional psychosocial model with interrelated

variables such as distress, pain catastrophizing, and negative expectancy. Because of variance

shared, it is likely that considering these variables together, as part of a larger "negative affect"

construct, will be better able to predict outcomes for patients with LBP. Finally, it is important

to continue to investigate fear-avoidance variables, as well as other psychosocial predictors,

because--due to the lack of biomedical explanations-psychosocial variables represent some of

the only intervention points currently available to patients with LBP. When compared to the

options of making no intervention or to expensive medical procedures, interventions based on

fear avoidance variables may prove to be cost effective and relatively useful, and should

therefore not be ignored as a possibility which warrants continued investigation.










LIST OF REFERENCES


Al-Obaidi, S. M., Al-Zoabi, B., Al-Shuwaie, N., Al-Zaabie, N., & Nelson, R. M. (2003). The
influence of pain and pain-related fear and disability beliefs on walking velocity in chronic
low back pain. hIt JRehabil Res, 26(2), 101-108.

Andersson, H. I., Ejlertsson, G., Leden, I., & Rosenberg, C. (1993). Chronic pain in a
geographically defined general population: studies of differences in age, gender, social
class, and pain localization. Clin JPain, 9(3), 174-182.

Asmundson, G. J., Norton, G. R., & Allerdings, M. D. (1997). Fear and avoidance in
dysfunctional chronic back pain patients. Pain, 69(3), 23 1-23 6.

Boersma, K., & Linton, S. J. (2006). Expectancy, fear and pain in the prediction of chronic pain
and disability: A prospective analysis. Eur JPain, 10(6), 551-557.

Bortz, W. M., 2nd. (1984). The disuse syndrome. West J2ed, 141(5), 691-694.

Burton, A. K., Tillotson, K. M., Main, C. J., & Hollis, S. (1995). Psychosocial predictors of
outcome in acute and subchronic low back trouble. Spine, 20(6), 722-728.

Burwinkle, T., Robinson, J. P., & Turk, D. C. (2005). Fear of movement: factor structure of the
tampa scale of kinesiophobia in patients with fibromyalgia syndrome. JPain, 6(6), 3 84-
391.

Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed. ed.). Hillsdale,
NJ: Erlbaum.

Crombez, G., Vervaet, L., Lysens, R., Baeyens, F., & Eelen, P. (1998). Avoidance and
confrontation of painful, back-straining movements in chronic back pain patients. Behav
M~odiJJ 22(1), 62-77.

Crombez, G., Vlaeyen, J. W., Heuts, P. H., & Lysens, R. (1999). Pain-related fear is more
disabling than pain itself: evidence on the role of pain-related fear in chronic back pain
disability. Pain, 80(1-2), 329-339.

Dionne, C. E., Bourbonnais, R., Fremont, P., Rossignol, M., Stock, S. R., Nouwen, A., et al..
(2006). Determinants of "return to work in good health" among workers with back pain
who consult in primary care settings: a 2-year prospective study. Eur Spine J.

Fairbank, J., Couper J, Davies JB, O'Brien JP. (1980). The Oswestry low back pain disability
questionnaire. Phys~ilotheiopy,, 66, 271-273.

Frank, J. W., Brooker, A. S., DeMaio, S. E., Kerr, M. S., Maetzel, A., Shannon, H. S., et al..
(1996). Disability resulting from occupational low back pain. Part II: What do we know
about secondary prevention? A review of the scientific evidence on prevention after
disability begins. Spine, 21(24), 2918-2929.










French, D. J., France, C. R., Vigneau, F., French, J. A., & Evans, R. T. (2007). Fear of
movement/(re)injury in chronic pain: a psychometric assessment of the original English
version of the Tampa scale for kinesiophobia (TSK). Pain, 12 7(1-2), 42-51.

Fritz, J. M., George, S. Z., & Delitto, A. (2001). The role of fear-avoidance beliefs in acute low
back pain: relationships with current and future disability and work status. Pain, 94(1), 7-
15.

Gatchel, R. J., Polatin, P. B., & Mayer, T. G. (1995). The dominant role of psychosocial risk
factors in the development of chronic low back pain disability. Spine, 20(24), 2702-2709.

George, S. Z., Dannecker, E. A., & Robinson, M. E. (2006). Fear of pain, not pain
catastrophizing, predicts acute pain intensity, but neither factor predicts tolerance or blood
pressure reactivity: an experimental investigation in pain-free individuals. Eur JPain,
10(5), 457-465.

George, S. Z., Fritz, J. M., Bialosky, J. E., & Donald, D. A. (2003). The effect of a fear-
avoidance-based physical therapy intervention for patients with acute low back pain:
results of a randomized clinical trial. Spine, 28(23), 2551-2560.

George, S. Z., Wittmer, V. T., Fillingim, R. B., & Robinson, M. E. (2007). Sex and pain-related
psychological variables are associated with thermal pain sensitivity for patients with
chronic low back pain. JPain, 8(1), 2-10.

Goubert, L., Crombez, G., Van Damme, S., Vlaeyen, J. W., Bijttebier, P., & Roelofs, J. (2004).
Confirmatory factor analysis of the Tampa Scale for Kinesiophobia: invariant two-factor
model across low back pain patients and fibromyalgia patients. Clin JPain, 20(2), 103-
110.

Grotle, M., Vollestad, N. K., & Brox, J. I. (2006). Clinical course and impact of fear-avoidance
beliefs in low back pain: prospective cohort study of acute and chronic low back pain: II.
Spine, 31(9), 1038-1046.

Grotle, M., Vollestad, N. K., Veierod, M. B., & Brox, J. I. (2004). Fear-avoidance beliefs and
distress in relation to disability in acute and chronic low back pain. Pain, 112(3), 343-352.

Haddock CK, R. D., Shadish WR. (1998). Using Odds Ratios as Effect Sizes for Meta-Analysis
of Dichotomous Data: A Primer on Methods and Issues. Psychological M~ethods, 3(3), 3 39-
353.

Hart, L. G., Deyo, R. A., & Cherkin, D. C. (1995). Physician office visits for low back pain.
Frequency, clinical evaluation, and treatment patterns from a U.S. national survey. Spine,


Hestback, L., Leboeuf-Yde, C., & Manniche, C. (2003). Low back pain: what is the long-term
course? A review of studies of general patient populations. Eur Spine J, 12(2), 149-165.










Klenerman, L., Slade, P. D., Stanley, I. M., Pennie, B., Reilly, J. P., Atchison, L. E., et al..
(1995). The prediction of chronicity in patients with an acute attack of low back pain in a
general practice setting. Spine, 20(4), 478-484.

Kopec, J. A., Esdaile, J. M., Abrahamowicz, M., Abenhaim, L., Wood-Dauphinee, S., Lamping,
D. L., et al.. (1996). The Quebec Back Pain Disability Scale: conceptualization and
development. J Clin Epidemiol, 49(2), 151-161.

Kottke, F. J. (1966). The effects of limitation of activity upon the human body. JamaJJ~~~~~JJJJJ~~~~~ 196(10),
825-830.

Lethem, J., Slade, P. D., Troup, J. D., & Bentley, G. (1983). Outline of a Fear-Avoidance Model
of exaggerated pain perception--I. Behav Res Ther, 21(4), 401-408.

Linton, S. J. (2000). A review of psychological risk factors in back and neck pain. Spine, 25(9),
1148-1156.

Linton, S. J., & van Tulder, M. W. (2001). Preventive interventions for back and neck pain
problems: what is the evidence? Spine, 26(7), 778-787.

Loeser, J. D. (1994). The prevention of needless pain: research opportunities. Prev M~ed, 23(5),
709-711.

Mannion, A. F., Junge, A., Taimela, S., Muntener, M., Lorenzo, K., & Dvorak, J. (2001). Active
therapy for chronic low back pain: part 3. Factors influencing self-rated disability and its
change following therapy. Spine, 26(8), 920-929.

Mantyselka, P., Kumpusalo, E., Ahonen, R., Kumpusalo, A., Kauhanen, J., Viinamaki, H., et al..
(2001). Pain as a reason to visit the doctor: a study in Finnish primary health care. Pain,
89(2-3), 175-180.

Mayer, T. G. (1991). Rational for Modern Spinal Care. In T. G. Mayer, Mooney V, & Gatchel
RJ (Ed.), Contemporary Conservative Care for Painful Spinal Disorders (pp. 3-9).
Philadelphia: Lea & Febiger.

Miller RP, K. S., Todd DD. (1991). Thze Tampa Scale for Kinesiophobia (Unpublished Report).

Picavet, H. S., Vlaeyen, J. W., & Schouten, J. S. (2002). Pain catastrophizing and kinesiophobia:
predictors of chronic low back pain. Am JEpidemiol, 156(11), 1028-1034.

Pincus, T., Burton, A. K., Vogel, S., & Field, A. P. (2002). A systematic review of psychological
factors as predictors of chronicity/disability in prospective cohorts of low back pain. Spine,
27(5), E109-120.

Roelofs, J., Goubert, L., Peters, M. L., Vlaeyen, J. W., & Crombez, G. (2004). The Tampa Scale
for Kinesiophobia: further examination of psychometric properties in patients with chronic
low back pain and fibromyalgia. Eur JPain, 8(5), 495-502.










Roland, M., & Fairbank, J. (2000). The Roland-Morris Disability Questionnaire and the
Oswestry Disability Questionnaire. Spine, 25(24), 3115-3124.

Roland, M., Morris R. (1983). A study of the natural history of back pain. Part I: development of
a reliable and sensitive measure of disability in low-back pain. Spine, 8, 141-144.

Schappert, S. (1989). National Ambulatory M~edical Care Survey (No. Vital Health Stat 13):
National Center for Health Statistics.

Scheer, S. J., Radack, K. L., & O'Brien, D. R., Jr. (1995). Randomized controlled trials in
industrial low back pain relating to return to work. Part 1. Acute interventions. Arch Phys
M~ed Rehabil, 76(10), 966-973.

Severeijns, R., Vlaeyen, J. W., van den Hout, M. A., & Weber, W. E. (2001). Pain
catastrophizing predicts pain intensity, disability, and psychological distress independent
of the level of physical impairment. Clin JPain, 1 7(2), 165-172.

Sieben, J. M., Vlaeyen, J. W., Portegijs, P. J., Verbunt, J. A., van Riet-Rutgers, S., Kester, A. D.,
et al.. (2005). A longitudinal study on the predictive validity of the fear-avoidance model
in low back pain. Pain, 117(1-2), 162-170.

Slade, P. D., Troup, J. D., Lethem, J., & Bentley, G. (1983). The Fear-Avoidance Model of
exaggerated pain perception--II. Behav Res Ther, 21(4), 409-416.

Staerkle, R., Mannion, A. F., Elfering, A., Junge, A., Semmer, N. K., Jacobshagen, N., et al..
(2004). Longitudinal validation of the fear-avoidance beliefs questionnaire (FABQ) in a
Swiss-German sample of low back pain patients. Eur Spine J, 13(4), 332-340.

Stang, P., Von Korff, M., & Galer, B. S. (1998). Reduced labor force participation among
primary care patients with headache. J Gen Intern M~ed, 13(5), 296-302.

Sternbach, R. A. (1986). Pain and 'hassles' in the United States: findings of the Nuprin pain
report. Pain, 27(1), 69-80.

Stewart, W. F., Ricci, J. A., Chee, E., Morganstein, D., & Lipton, R. (2003). Lost productive
time and cost due to common pain conditions in the US workforce. JamaJJ~~~~~JJJJJ~~~~~ 290(18), 2443-
2454.

Sullivan, M. J., Thorn, B., Haythornthwaite, J. A., Keefe, F., Martin, M., Bradley, L. A., et al..
(2001). Theoretical perspectives on the relation between catastrophizing and pain. Clin J
Pain, 1 7(1), 52-64.

Swinkels-Meewisse, I. E., Roelofs, J., Schouten, E. G., Verbeek, A. L., Oostendorp, R. A., &
Vlaeyen, J. W. (2006). Fear of movement/(re)injury predicting chronic disabling low back
pain: a prospective inception cohort study. Spine, 31(6), 658-664.










Tacci, J. A., Webster, B. S., Hashemi, L., & Christiani, D. C. (1998). Healthcare utilization and
referral patterns in the initial management of new-onset, uncomplicated, low back workers'
compensation disability claims. J Occup Environ M~ed, 40(1 1), 958-963.

Turk, D., Melzack R. (2001). The measurement of pain and the assessment of people
experiencing pain. In D. C. Turk, Melzack R. (Ed.), Handbook ofpain assessment (2nd ed.
ed.). New York: Guilford.

Vlaeyen, J. W., Kole-Snijders, A. M., Boeren, R. G., & van Eek, H. (1995). Fear of
movement/(re)injury in chronic low back pain and its relation to behavioral performance.
Pain, 62(3), 363-372.

Vlaeyen, J. W., & Linton, S. J. (2000). Fear-avoidance and its consequences in chronic
musculoskeletal pain: a state of the art. Pain, 85(3), 317-332.

Waddell, G., Newton, M., Henderson, I., Somerville, D., & Main, C. J. (1993). A Fear-
Avoidance Beliefs Questionnaire (FABQ) and the role of fear-avoidance beliefs in chronic
low back pain and disability. Pain, 52(2), 157-168.

Walker, B. F., Muller, R., & Grant, W. D. (2004). Low back pain in Australian adults:
prevalence and associated disability. J2anipulative Physiol Ther, 2 7(4), 23 8-244.

Watson, P. J., Main, C. J., Waddell, G., Gales, T. F., & Purcell-Jones, G. (1998). Medically
certified work loss, recurrence and costs of wage compensation for back pain: a follow-up
study of the working population of Jersey. Br JRheumatol, 3 7(1), 82-86.

Woby, S. R., Watson, P. J., Roach, N. K., & Urmston, M. (2004). Are changes in fear-avoidance
beliefs, catastrophizing, and appraisals of control, predictive of changes in chronic low
back pain and disability? Eur JPain, 8(3), 201-210.









BIOGRAPHICAL SKETCH

Alisa Diane Hassinger was born on May 21, 1973 in Harrisburg, Pennsylvania. The

youngest of two, she grew up in the greater Harrisburg area, graduating from Millersburg Area

High School in 1991. She earned her B.A. in psychology from Indiana University of

Pennsylvania. Upon graduating with honors in 1995, she began graduate studies in social work

at Arizona State University. Alisa graduated with Master of Social Work in 1997, and

subsequently accepted a commission to serve in the United States Army as a social work officer.

Upon her honorable discharge from the military in 2003, Alisa continued to work for the

Department of Defense at Fort Benning, Georgia as a case manager and therapist for soldiers

with deployment related mental health concerns. Alisa relocated to Gainesville, Florida in

August of 2005 to begin her graduate career in clinical psychology. Upon completion of the

M. S., Alisa will continue on in her program and apply for doctoral candidacy in the Department

of Clinical and Health Psychology at the University of Florida.