Running head: EXPECTATIONS AND PAIN RELIEF IN LOW BACK PAIN 1 The Effect of Expectation on Pain Relief in Individuals with Low Back Pain Alessandra N. Conto University of Florida
EXPECTATIONS AND PAIN RELIEF IN LOW BACK PAIN 2 Abstract Low back pain (LBP) is an epidemic incurring tremendous costs. xpectation s for pain relief have a significant role in outcomes related to musculoskeletal pain. We investigated factors predictive of baseline expectation for changes in clinical outcomes in individuals pre senting with LBP and the predictive value of expectation on two week changes in clinical outcomes. Usual pain, pain catastrophizing, depression, frustration, and sex were significantly associated with baseline expectations of pain reduction. Usual pain and sex were significant variables in the regression model. Baseline expected chang e in pain, duration of pain, frustration, and income were significantly associated with change in clinical pain. Expected change in pain and duration of pain were significant variables in the regression model. Intervention did not affect clinical outcomes; however, individuals with high expectations had significantly greater pain reduction than those with low expectations, highlig hting the role of expectation in musculoskeletal pain outcomes. Growing knowledge of psychological effects on musculoskeletal conditions suggests that the biopsychosocial approach may be more effective than the classic anatomical approach in treating cases of LBP.
EXPECTATIONS AND PAIN RELIEF IN LOW BACK PAIN 3 The Effect of Expectations on Pain Relief in Individuals with Low Back Pain Introduction Low back pain (LBP) has reached epidemic proportions, affecting at least 80% of people at some point in their lives (Jonsdottir, Rainero, Racca, Glassel, & Cieza, 2010). The majority of cases occur in individuals between the ages of 30 and 59, affecting their most productive years and contributing to long term disability and work absenteeism (Gurcay et al., 2009; Jonsdottir et al., 2010). Low back pain incurs tremendous costs, including lost productivity and lost income from work, significant medical, r ehabilitation and surgical interventions, and costs associated with disability related loss of dail y function (Browning, 2011 affected by low back pain, and functions principally hindered are neuromusculoskeletal and mo vement related (Jonsdottir et al., 2010 ). Current literature indicates that factors other than correction of physical impairments influence clinical outcomes in patients with musculoskeletal conditions. Specifically, ph ysical causes can be identified in only 15% of cases of LBP and anatomical findings such as arthritic changes or herniations are often found in pain free individuals or do not relate to pain in people experiencing LBP (Deyo, 2002 ; Feu erstein & Beattie, 1995 ). This has led to a biopsychosocial approach to LBP, and psychological factors such as fear, catastrophizing, and expectation may be more relevant than physical impairments. The b iopsychosocial model of health has become increasingly understood, indicating complex and interde pendent relationships between physical biomedical, and psychological and social features of LBP that present concomitantly (Foster & Delitto, 2011). E xpectation has been consistently associated with patient outcomes related to musculoskeletal p ain condit ions suggesting its role in cases of low back pain (Bialosky, Bishop, & Cleland, 2010).
EXPECTATIONS AND PAIN RELIEF IN LOW BACK PAIN 4 S everal studies have demonstrated the effects of expectation on pain relief outcomes. Linde et al. (2007) conducted four randomized control trials comparing acupunc ture, superficial needling at non acupuncture sites, and a no treatment control group in patients with migraine, tension type headache, chronic low back pain, and osteoarthritis of the knee. Participants were asked about their attitudes towards acupuncture in general, as well as their expectations regarding their individual pain relief outcomes Patients with high expectations reported better outcomes than patients with low expectations both after treatment and at a follow up four months later. A study conducted by Myers et al. (2007) demonstrated similar results. Patients with acute low back pain received usual care or us ual care plus patient choice of acupuncture, chiropractic, or massage therapy t their expectations regarding different therapies were significan tly associated with better outc omes at five and twelve weeks. Once again, higher treatment expectations were correlated with better outcomes. Similarly, Kalauokalani, Cherkin, Sherman, Koepsell, & Deyo (2001) conducted a study in which patients with low back pain were assigned to either an acupuncture treatment or massage therapy. Expectation regarding the benefits of each treatment was strongly associated with clinical outcomes, with a fivefold greater lik elihood of improvement for patients with higher expectations. Collectively, this body of literature suggests a powerful effect of expectation on outcomes related to musculoskeletal pain. Expectation may be more relevant in cases of LBP than the typical anatomical approach. Aims and Hypotheses The purpose of this study was to determine which baseline demographic and psychological factors were predictive of baseline expectation for changes in clinical outcomes in individuals presenting with LBP. Additionally, we wished to determine the predictive v alue of
EXPECTATIONS AND PAIN RELIEF IN LOW BACK PAIN 5 baseline expectation on two week changes in clinical pain in individuals presenting with LBP. We hypothesized that individuals with expectations for greater improvements in clinical pain would experience better outcomes than individuals with lower expectations. Method This study represents a planned secondary analysis of a primary investigation of the efficacy of spinal manipulation for individuals experiencing LBP Participants a ges 18 60 with LBP rated as 4/10 or higher during the last 24 hours were included. Participants were excluded if they had surgery for LBP within the past six months or fracture as a cause of LBP Individuals meeting the criteria and agreeing to participate signed an informed consent form as mandated by the University of Florida Institutional Review Board. Participants completed a demographic questionnaire regarding sex, age, employment status, lit igation status, marital status, educational level, and duration of LBP They completed questionnair es related to anxiety, pain catastrophizing, fear of pain, usual pain, and their expectations for pain relief. These included the Patient Centered Outcome Questionnaire, the Fear of Pain Questionnaire, the Pain Catastrophizing Scale, and the State Trait Anxiety evaluation, among others. Clinical pain and expectation were measured using 0 (none) to 100 (worst pain imaginable) numeric rating scales for usual pain and expected pain following the study. P articipant s were randomly assigned to a manual therapy intervention, a placebo, or no intervention. Participants returned for reassessment two weeks after the initia l session. Participants receiving the spinal manipulation intervention or placebo interventions were seen for four additional sessions between testing sessions to receive their assigned interventions. Correlation coefficients were determined for demograp hic variables, psychological variables, clinical pain, expectation, and change in pain. Significantly associated variables were entered into separate regression models for baseline
EXPECTATIONS AND PAIN RELIEF IN LOW BACK PAIN 6 expectation and change in clinical pain. Mean expectation for change in p ain was determined. Participants were categorized as high expectations for pain relief ( pain < mean rating ) or low expectation s for pain relief ( pain mean rating ). A group (high vs. low expectation) by time repeated measures ANOVA explored the relationship between expectation and two week changes in clinical pain. Results This study included 83 participants, 72% of which were female. The mean age was 31.5 (sd = 11.9) years. The mean duration of p ain was 215.6 (sd = 403.0) weeks. Basel ine pain was 41.5 (sd = 23.7). B aseline expected percent change in pain was 36.5 (sd = 48.2) %. The two week percentage change in pain was 22.1 (sd = 63.5) %. Usual pain, pain catastrophizing, depression, frustration, and sex were significantly associated with baseline expectations of pain reduction (p<0.05). Usual pain and sex were significant variables (p<0.05) in the regression model. Baseline expected change in pain, duration of pain, frustration, and income were significantly associated with change in clinical pain (p<0.05). Expected change in pain and duration of pain were significant variables (p<0.05) in the regression model. A group by time interaction wa s observed (p=0.04). Individuals with low expectation demonstrated a 6.8 (sd = 20.2), (p=0.04) point decrease in LBP while individuals with high expectations demonstrated a 16.0 (sd = 18.4), (p<0.01) point decrease in LBP. Discussion Expectation is a r elevant factor in the outcomes associated with interventions for musculoskeletal pain conditions (Kalauokalani et al., 2001; Linde et al., 2007; Myers et al., 2007 ). Subsequently, knowledge of factors influencing baseline expectation and the role of
EXPECTATIONS AND PAIN RELIEF IN LOW BACK PAIN 7 expect ation in predicting pain relief in participants receiving spinal manipulative therapy is relevant. Usual pain, pain catastrophizing, depression, frustration, and sex were all significantly related to baseline expectation for pain. Only usual pain and sex remained as significant predictors within our regression model. Our findings are similar to those of others who observed sex as influential in predicting expectation and suggests men and women may differ in their baseline expectation for treatments for m usculoskeletal pain conditions (Gepstein, Arinzon, Adunsky, & Folman, 2006; Goldstein, Morgenstern, Hurwitz, & Yu, 2009 ; Ozegovic, Carroll, & David, 2009). Interestingly, psychological factors found relevant in other studies were not significant predictor s of baseline expectation in our study (Goossens, Vlaeyen, Hidding, Kole Snijders, & Evers 2005) Other studies were performed in participants seeking treatment for pain conditions while our sample were individuals with low back pain responding to a study Subsequently, psychological factors may play a greater role in individuals specifically seeking treatment for pain conditions. Our study supported our hypothesis that expectation plays a significant role in clinical outcomes of individuals experiencing LBP, such that individuals with high expectations experienced greater pain reduction than individuals with low expectations. The inadequacy of the p atho anatomical approach for low back pain has le d to the biopsychosocial approach suggesting a pertinent role for psychological factors in associated outcomes (Leeuw et al., 2007) Our findings are consistent with a biopsychoso c i al model of low back pa in and prior studies such as Linde et al. (2007), Myers et al. (2007), and Kalauokalani et al. (2001) in suggesting a powerful effect of expectation on outcomes related to musculoskeletal pain. In addition to finding results consistent to prior investig ations this study also had strengths such as a fairly large sample size of 83 participants. The longitudinal design of our
EXPECTATIONS AND PAIN RELIEF IN LOW BACK PAIN 8 over a period of two weeks and compare it to their baseline pain. We also utilized the Patient Centered Outcomes Questionnaire (PCOQ), which is a validated measure of expectation investigated by Robinson et al. (2005). This study also had se veral weaknesses, though. P articipants in this study were experiencing LBP but were not seeking clinical care. Therefore, the results of this study may not be generalizable to a clinical population of individu als seeking treatment for LBP. Also, this study was a secondary analysis of a previous study and was not intended to be the primary investigation Because there is difficulty in identifying effective interventions for patients with LBP classification has been suggested as a way to identify homogeneous groups of individuals with low back pain likely to respond posit ively to specific interventions (Fritz, Cleland, & Childs, 2007). C linical prediction rules have been established that may help match patients to specific interventions that will be successful for them (Flynn et al., 2002). Spinal manipulation is a treatment that is commonly used for individuals with LBP, and the clinical prediction rules for spinal manipulation have been investigated using five criteria. These include the duration of the current episode of LBP, the extent of dist al symptoms, the fear avoidance beliefs questionnaire work subscale, segmental mobility testing, and hip internal rotation range of motion (Flynn et al., 2002) Expectations have not been explored as criteria in clinical prediction rules for LBP; however with increasing knowledge of the impact of expectations on clinical outcomes, future studies should consider patient expectations as a potentially relevant variable in individuals likely to respond positively to specific interventions for LBP.
EXPECTATIONS AND PAIN RELIEF IN LOW BACK PAIN 9 Other future implications of this study may include investigating the effect of patient expectations on pain relief in clinical settings. If expectations are significant predictors of pain relief in clinical settings, health care providers may consider ca pitalizing on the effects of expectations by measuring expectation and appropriately manipulating expectations to realistic levels as Further research is needed before any recommendations may be made.
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