Exploring factors influencing asthma control and asthma-specific health-related quality of life among children

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Title:
Exploring factors influencing asthma control and asthma-specific health-related quality of life among children
Physical Description:
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English
Creator:
Gandhi, Pranav K.
Kenzik, Kelly M.
Thompson, Lindsay A.
DeWalt, Darren A.
Revicki, Dennis A.
Shenkman, Elizabeth A.
Huang, I-Chan
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BioMed Central (Respiratory Research)

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Abstract:
Background: Little is known about factors contributing to children’s asthma control status and health-related quality of life (HRQoL). The study objectives were to assess the relationship between asthma control and asthmaspecific HRQoL in asthmatic children, and to examine the extent to which parental health literacy, perceived selfefficacy with patient-physician interaction, and satisfaction with shared decision-making (SDM) contribute to children’s asthma control and asthma-specific HRQoL. Methods: This cross-sectional study utilized data collected from a sample of asthmatic children (n = 160) aged 8–17 years and their parents (n = 160) who visited a university medical center. Asthma-specific HRQoL was selfreported by children using the National Institutes of Health’s Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Asthma Impact Scale. Satisfaction with SDM, perceived self-efficacy with patient-physician interaction, parental health literacy, and asthma control were reported by parents using standardized measures. Structural equation modeling (SEM) was performed to test the hypothesized pathways. Results: Path analysis revealed that children with better asthma control reported higher asthma-specific HRQoL (β = 0.4, P < 0.001). Parents with higher health literacy and greater perceived self-efficacy with patient-physician interactions were associated with higher satisfaction with SDM (β = 0.38, P < 0.05; β = 0.58, P < 0.001, respectively). Greater satisfaction with SDM was in turn associated with better asthma control (β = −0.26, P < 0.01). Conclusion: Children’s asthma control status influenced their asthma-specific HRQoL. However, parental factors such as perceived self-efficacy with patient-physician interaction and satisfaction with shared decision-making indirectly influenced children’s asthma control status and asthma-specific HRQoL. Keywords: Asthma control, Health-related quality of life, PROMIS, Satisfaction with shared decision-making, Perceived self-efficacy with patient-physician interaction, Structural equation modeling.
General Note:
Publication of this article was funded in part by the University of Florida Open-Access publishing Fund. In addition, requestors receiving funding through the UFOAP project are expected to submit a post-review, final draft of the article to UF's institutional repository, IR@UF, (www.uflib.ufl.edu/UFir) at the time of funding. The institutional Repository at the University of Florida community, with research, news, outreach, and educational materials.
General Note:
Gandhi et al. Respiratory Research 2013, 14:26 http://respiratory-research.com/content/14/1/26; Pages 1-10
General Note:
doi:10.1186/1465-9921-14-26 Cite this article as: Gandhi et al.: Exploring factors influencing asthma control and asthma-specific health-related quality of life among children. Respiratory Research 2013 14:26.

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RESEARCHOpenAccessExploringfactorsinfluencingasthmacontroland asthma-specifichealth-relatedqualityoflife amongchildrenPranavKGandhi1,KellyMKenzik2,LindsayAThompson3,DarrenADeWalt4,DennisARevicki2,5, ElizabethAShenkman2,6andI-ChanHuang2,6*AbstractBackground: Littleisknownaboutfactorscontributingtochildren ’ sasthmacontrolstatusandhealth-related qualityoflife(HRQoL).ThestudyobjectivesweretoassesstherelationshipbetweenasthmacontrolandasthmaspecificHRQoLinasthmaticchildren,andtoexaminetheextenttowhichparentalhealthliteracy,perceivedselfefficacywithpatient-physicianinteraction,andsatisfactionwithshareddecision-making(SDM)contributeto children ’ sasthmacontrolandasthma-specificHRQoL. Methods: Thiscross-sectionalstudyutilizeddatacollectedfromasampleofasthmaticchildren(n=160)aged 8 – 17yearsandtheirparents(n=160)whovisitedauniversitymedicalcenter.Asthma-specificHRQoLwasselfreportedbychildrenusingtheNationalInstitutesofHealth ’ sPatient-ReportedOutcomesMeasurementInformation System(PROMIS)PediatricAsthmaImpactScale.SatisfactionwithSDM,perceivedself-efficacywithpatient-physician interaction,parentalhealthliteracy,andasthmacontrolwerereportedbyparentsusingstandardizedmeasures. Structuralequationmodeling(SEM)wasperformedtotestthehypothesizedpathways. Results: Pathanalysisrevealedthatchildrenwithbetterasthmacontrolreportedhigherasthma-specificHRQoL ( =0.4, P <0.001).Parentswithhigherhealthliteracyandgreaterperceivedself-efficacywithpatient-physician interactionswereassociatedwithhighersatisfactionwithSDM( =0.38, P <0.05; =0.58, P <0.001,respectively). GreatersatisfactionwithSDMwasinturnassociatedwithbetterasthmacontrol( = 0.26, P <0.01). Conclusion: Children ’ sasthmacontrolstatusinfluencedtheirasthma-specificHRQoL.However,parentalfactors suchasperceivedself-efficacywithpatient-physicianinteractionandsatisfactionwithshareddecision-making indirectlyinfluencedchildren ’ sasthmacontrolstatusandasthma-specificHRQoL. Keywords: Asthmacontrol,Health-relatedqualityoflife,PROMIS,Satisfactionwithshareddecision-making, Perceivedself-efficacywithpatient-physicianinteraction,StructuralequationmodelingIntroductionAsthmaisachronicdiseasecausedbyinflammation oftheairwaysthatleadstonarrowedairwaysorbronchoconstriction[1].Childrenaged0 – 17yearshave higherasthmaprevalence(9.6%)comparedwithadults (7.7%)intheUS[2].Previousstudieshaveshowedthat amongchildrenwithasthmatheprevalenceofpoorlycontrolledasthmastatusvaried(32%-64%)[3-5].For example,onestudyreported46%oftheasthmatic childrenwhousedinhaledcorticosteroidshadpoorlycontrolledasthma[5].Inadequateasthmacontrolcauses anincreaseinthefrequencyandsometimestheseverity ofasthmaattacks[6,7].Asthmacontrolisamultidimensionalconceptwhichisdefinedas “ patientreports ofdaytimeandnocturnalsymptoms,activitylimitations duetoasthma,needforrescuemedications,andmeasuresoflungfunction[8]. ” TheAsthmaGuidelinesof theNationalAsthmaEducationandPreventionProgram (NAEPP)publishedbytheNationalInstitutesofHealth *Correspondence: ichuang@ufl.edu2DepartmentofHealthOutcomesandPolicy,CollegeofMedicine,University ofFlorida,Gainesville,FL,USA6InstituteforChildHealthPolicy,CollegeofMedicine,UniversityofFlorida, Gainesville,FL,USA Fulllistofauthorinformationisavailableattheendofthearticle 2013Gandhietal.;licenseeBioMedCentralLtd.ThisisanOpenAccessarticledistributedunderthetermsoftheCreative CommonsAttributionLicense(http://creativecommons.org/licenses/by/2.0),whichpermitsunrestricteduse,distribution,and reproductioninanymedium,providedtheoriginalworkisproperlycited.Gandhi etal.RespiratoryResearch 2013, 14 :26 http://respiratory-research.com/content/14/1/26

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(NIH)emphasizetheneedtoevaluateasthmacontrolas akeycomponentforasthmatreatmentandmanagement [8-11]. Well-controlledasthmaisassociatedwithimproved healthstatus[12],andfewerphysicianvisits,hospitalizationsandemergencyroomvisitsamongchildrenand adults[11,13].Incontrast,poorasthmacontrolisdirectlylinkedwithincreasedschoolabsenteeismandloss inworkproductivityamongasthmachildrenandadults/ caregivers,respectively[14,15].Unfortunately,studies reportthatasthmaremainsuncontrolledinmanyasthmaticpatients,despitereceivingappropriatetreatments [16].Patient-reportedoutcomes,suchashealth-related qualityoflife(HRQoL),areusefulindicatorstounderstandtheimpactofpoorasthmacontrolonfunctional statusandwell-being[17].Severalstudieshaveinvestigatedtheimpactofasthmacontrolonasthma-specific andgenericHRQoL,wherepoorlycontrolledasthma wasfoundtobeassociatedwithlowerHRQoLscores [13-15].ThemostrecentNAEPPguidelines(2007update)emphasizetheneedtoinvestigatetheimpactof asthmacontrolonHRQoL[9],especiallysinceclinicians donotstrictlyfollowtheNAEPPguidelinestoaddress asthmacontrolstatus[14,18]. Factorsinfluencingasthmacontrol,whichinturnaffectHRQoL,arecomplexandundetermined[8,17].Previousstudieshaveconsistentlyidentifiedthatindividual factorssuchasgenetics,smoking,poordesignofinhalerdevice,impropermedicationcompliance,aswellas familyandenvironmentalfactorssuchaspetsinthe home,airpollution,andpollenexposureareimportant determinantsofpoorlycontrolledasthma[9,19,20].Recently,moreattentionhasbeenfocusedontheimpact ofparentalfactorsonasthmaoutcomes.Parentalhealth literacyofchildrenwithasthma,forexample,isone suchfactorthatmightdirectlycontributetotheoptimal asthmacareoftheirchildren[21].Lowhealthliteracy levelscouldinfluenceparents ’ understandingofasthma etiologyandimpactcapabilityofengaginginthedecision-makingprocesswithproviders,andcompliance withthetreatmentplan.TheNAEPPguidelinesemphasizethatphysiciansshouldengagechildrenandparents inthedecision-makingprocessandassessmentofasthmacontrolforeffectiveasthmamanagement[9].Higher healthliteracywasassociatedwithhigherperceivedselfefficacyinasthmamanagementoragreaterdesireto activelyengageinthedecision-makingprocess[22,23], whereasanotherstudycouldnotreplicatethesefindings [24].Inaddition,severalstudieshaveshownparental factorssuchashealthliteracy,self-efficacyorsatisfactionwiththedecision-makingprocesstobesignificantly associatedwithasthmaoutcomes,includingHRQoL [25-27].Nevertheless,limitedevidenceisavailableexaminingthecomplexrelationshipsamongparentalhealth literacy,perceivedself-efficacywithpatient-physician interaction,andsatisfactionwithshareddecision-making (SDM),especiallytheimpactofthesefactorsonpediatricasthmaoutcomes. Thepresentstudyaimedtoassesstherelationship betweenasthmacontrolandHRQoLinchildrenwith asthma.Weanticipatedthatincontrasttochildrenwith goodasthmacontrol,childrenwithpoorasthmacontrol wouldreportpoorerasthma-specificHRQoL.Second, weaimedtoexaminehowparentalhealthliteracy,perceivedself-efficacywithpatient-physicianinteraction, andsatisfactionwithSDMcontributedtochildren ’ s asthmacontrolandasthma-specificHRQoL.Wehypothesizedthatgreaterparentalhealthliteracyandgreater perceivedself-efficacywouldbesignificantlyassociated withhighersatisfactionwithSDM,andinturnhigher satisfactionwithSDMwouldbeassociatedwithbetter pediatricasthmacontrolstatusandasthma-specific HRQoL.Specifically,weusedstructuralequationmodeling(SEM)tosimultaneouslyanalyzethecomplexrelationshipsamongtheaforementionedvariables.Thepresent studywillextendtheliteraturetodemonstrateimportant factorsthatcontributetopediatricasthmacontroland asthma-specificHRQoL.MethodsDatasources,datacollection,andstudysampleThisisacross-sectionalstudyusingdatacollectedfrom asampleofasthmaticchildren(n=160)aged8 – 17years andtheirparents/guardians(n=160)whovisitedfive pediatricclinicswithintheUniversityofFlorida(UF) HealthScienceCenterinGainesville,Florida.Theclinics includePediatricPrimaryCareatGeroldL.Schiebler CMSCenterandTowerSquare,PediatricAfterHours Clinic,PediatricAllergyClinic,andPediatricPulmonary Clinic.Duringtheclinicalappointment,physiciansof thefivepediatricclinicsidentifiedeligibleparticipants basedonthefollowingenrollmentcriteria:agerange, symptomsandmedicationuseasindicatedinthemedicalrecord,andfluencylevelinEnglishlanguage.Physiciansusedtheasthmaticsymptomsandmedication useassuggestedinNAEPPasthmaguidelinetodetermineasthmastatus[9].Eligibleparticipantsweresubsequentlyreferredtoresearchassistantswhowereinthe waitingroomarea.Researchassistantsguidedtheparentstocompletewritteninformedconsentform(and childrenneededtoassent),followedbyacompletionof surveyquestionnairesinaquietroomoftheclinic.We didnotaskphysicianstocountthenumberofeligible subjectswhodeclinedtoparticipateinpartduetothe busyscheduleinclinics.Datawerecollectedbetween April2010andSeptember2011.UF ’ sInstitutionalReview Boardapprovedthestudyprotocol.Gandhi etal.RespiratoryResearch 2013, 14 :26 Page2of10 http://respiratory-research.com/content/14/1/26

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MeasurementsinsurveyAsurveyquestionnairecomprisedofdifferentmeasures wasadministeredseparatelytochildrenandtheirparents.Specifically,childrenansweredtheitemsmeasuringasthma-specificHRQoL,andparentsanswered itemsmeasuringhealthliteracy,self-efficacywithpatient-physicianinteraction,satisfactionwithSDM,and asthmacontrol.Asthma-specificHRQoLAsthma-specificHRQoLscaleisoneoftheNIH ’ s Patient-ReportedOutcomesMeasurementInformation System(PROMIS)pediatricscalesthataredesigned tomeasureimportantdomainsofpediatricpatientreportedoutcomes[28].Thepresentstudyusedthe asthmaimpactdomain(8items)tomeasureasthmaspecificHRQOLinchildren.Theresponsecategoriesfor eachofthe8itemsarenever,almostnever,sometimes, oftenandalmostalways.Eachitemasksthechildren themselvesaboutasthmarelevantsymptomsinthepast sevendaysbeforetheinterview.Thedomainscorewas calculatedbyitemresponsetheory(IRT),withameanof 50andSDof10,andhigherscoresforgreaterimpairmentinHRQOL.Thescalehasdemonstratedhigh measurementprecisionandconstructvaliditybasedon IRT[28].AsthmacontrolAsthmacontrolwasmeasuredusinga10-itemparentalquestionnaire,whichwasdevelopedbasedonthe NAEPPAsthmaGuidelinespublishedbytheNIH[29]. Theparentsofchildrenwithasthmawereaskedabout howofteninthepastsevendayshis/herchildbeing botheredbyasthmasymptoms,numberofdaysfor asthmasymptoms,useofrescuemedications,numberof dayschildwithanasthmaattack,activitylimitationsdue ofasthma,andhis/herchildbeingwokenbyasthma. Theasthmacontrolquestionnairehasdemonstratedgood psychometricproperties,includinginternalconsistency reliability,convergent/discriminantvalidity,andknowngroupsvalidity[29].Eachitemintheasthmacontroldomainisdichotomizedasnocontrolproblemversusa controlproblem,whereintermittentstatusisconsidered ascontrolledandpersistentstatusisconsideredasnot controlled.Foreachpatient,thevaluesofthefiveitems aresummarizedtogenerateanindexrangingfrom0to5, with0 – 1indicating “ goodcontrol ” and2 – 5indicating “ poorcontrol. ”HealthliteracyParentalhealthliteracywasmeasuredusingtheShortTest ofFunctionalHealthLiteracyinAdults(S-TOFHLA)[30]. Theinstrumenthasdemonstratedexcellentpsychometricproperties,includinginternalconsistencyreliability (Cronbach ’ salpha=0.98)andtest-retestreliability. S-TOFHLAconsistsof36itemswhereeachitemis dichotomizedandscoredas “ 1 ” forcorrectand “ 0 ” forincorrect.Asummedoverallscore(range:0 – 36)for healthliteracyitemsiscalculated,wherehigherscoresindicategreaterhealthliteracy.S-TOFHLAscaleisdivided intothreecategoriesoffunctionalliteracy:inadequate (0 – 16),adequate(17 – 22),andfunctional(23 – 36).Based onthescoringguideline,weclassifiedparentswithscores<23asinadequateormarginalfunctionalhealthliteracy,whereasthosewithscores 23asadequatefunctional healthliteracy[30].Perceivedself-efficacywithpatient-physicianinteractionPerceivedself-efficacywithpatient-physicianinteraction (PEPPI)wasmeasuredusingastandardizedscalecomprisedof10items[31].Afive-pointresponsecategory foreachitemwasutilized(from “ notatall ” to “ very much ” ).ThetotalscoresforthePEPPIscalerangefrom 0to50.Higheritemandscalescoresindicategreater perceivedself-efficacywithpatient-physicianinteraction. Thescalehasdemonstratedhighinternalconsistencyreliability(Cronbach ’ salpha=0.91)andconvergentand discriminantvalidity[31].SatisfactionwithSDMSatisfactionwithshareddecision-makingforparentswas measuredusingastandardizedscalecomprisedofnine items[32].Asix-pointresponsecategoryforeachitem wasutilized(from “ completelydisagree ” to “ completely agree ” ).Asummedrawtotalscorerangingfrom0to45 wascreated.Higheritemandhigherscalescoresindicategreatersatisfactionwithshareddecision-making. ThescalehasdemonstratedexcellentinternalconsistencyreliabilitywithaCronbach ’ salphaof0.94,aswellas acceptablefacevalidity[32].StatisticalanalysisDescriptiveanalyses,includingmeansandstandarddeviations,wereperformedtodocumentthecharacteristics ofchildrenandtheirparents.Pearson ’ scorrelationcoefficientwascalculatedtodemonstratethemagnitude oftheassociationbetweenthevariables(i.e.,asthmaspecificHRQoL,asthmacontrol,perceivedself-efficacy withpatient-physicianinteraction,satisfactionwithSDM, andparentalhealthliteracy). LISREL8.8[33]wasusedtoperformSEMandSAS 9.1software[34]wasusedfortheremaininganalyses. Conventionally,regressionanalysishasbeenusedtoexaminetherelationshipbetweeneachdependentvariable andoneormoreindependentvariables.InSEM,avariablemayserveasanindependent,mediating,ordependentvariabledependinguponthespecificrolethe variableplays.OnevariableservingasadependentGandhi etal.RespiratoryResearch 2013, 14 :26 Page3of10 http://respiratory-research.com/content/14/1/26

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variableinoneregressionmodelcanserveasanindependentormediatingvariableinotherregressionmodels.Forexample,inoneregressionmodel,asthma controlisthemediatingvariablebetweensatisfaction withshareddecision-making(independentvariable)and asthma-specificHRQOL(dependentvariable),whereas inanotherregressionmodel,asthmacontrolisthe dependentvariablethatisinfluencedbyhealthliteracy (independentvariable)andsatisfactionwithshared decision-making(mediatingvariable).Avariableisqualifiedasamediatorifthemediatingroleissignificant inpathanalyses(e.g.,anindependentvariableissignificantlyassociatedwithamediatingvariableandthis mediatingvariableissignificantlyassociatedwithdependentvariable)andthetotaleffectofthispathanalysisis significantaswell.AnotheruniquefeatureoftheSEM applicationisallowingthesimultaneoustestingofthe measurementandthestructuralpartsinthesameanalyticframework.Themeasurementpartbuildstherelationshipsbetweentheconceptofinterest(e.g.,HRQoL) andindicators(i.e.,items)designedtomeasurethatspecificconcept.Thestructuralpartbuildstherelationship betweenthevariablesofinterestthatwerepre-specified inourconceptualframework[35,36]. Theselectionofvariablesintothepathanalysesis basedonevidencefromtheliterature,ourconceptual framework,andresultsofbivariateanalyses.Wedidnot solelyrelyontheresultsofbivariateanalysestoguide thepathanalysesbecausebivariateanalysesdonotaccountfortheinfluenceofconfoundingvariablesonthe relationshipsamongindependent,mediating,anddependentvariables.InthemeasurementpartoftheSEM,we treatedself-efficacywithpatient-physicianinteraction, satisfactionwithSDM,asthmacontrolandasthma-specific HRQoLaslatentvariables,whichwereindirectlymeasured usingtheitemsofinstruments.Wealsocalculatedinternal consistency(Cronbach ’ salpha)foreachlatentvariable, withavalueof 0.7deemedsatisfactory. ThestructuralpartoftheSEMinvolvesapathanalysistoestimateregressioncoefficientsrepresentingthe directrelationshipsbetweenvariablesofinterests.Inaddition,SEMallowsanalyzingtheindirecteffectsofindependentvariablesondependentvariablesthroughthe effectsofmediatingvariables.Mediatingeffectsshow theimpactofapredictorvariableonthespecificvariable ofinterestwhichispartiallyorcompletelyexplainedby anothervariable.Asaforementioned,pathanalysesare theextensionofregressionmodels,anddifferentcovariatesthatconfoundtherelationshipsamongindependent,mediating,anddependentvariablescanbeadjusted. Basedontheliterature,parents ’ ageandgender,children ’ sageandgender,andphysician ’ sreportofpediatric comorbidconditionsareimportantcovariates;therefore, weincludedthesevariablesascovariatesinthepath analyses.Wetreatedhealthliteracyasanindependent variable;however,weregardedhealthliteracyasanobservedratherthanalatentvariablebecausethe meaningfulcutoffs fordifferentlevelsofhealthliteracywhich havebeenestablishedbythedeveloperswereestimated basedontheobservedscores. IndicesofmodelfitwereestimatedtoexaminetheappropriatenessoftheSEM,includingthegoodness-of-fit chi-square( 2)andRootMeanSquareErrorofApproximation(RMSEA).Avaluebelow0.08onRMSEAis deemedagoodmodelfitandavaluebelow0.05orless isdeemedaclosefit[37].ResultsCharacteristicsofthestudysampleTable1showsthecharacteristicsofchildrenwithasthma(n=160)andtheirparents(n=160).Children ’ sage rangedfrom8to17years(mean11.61years;SD2.41years).Majorityofthechildreninthesamplewerefemales(n=95),andhad 1comorbidcondition(n=103). Approximatelyhalfofthechildrenhadgood(n=77)and poor(n=83)asthmacontrol.Parents ’ agerangedfrom25 to68years(mean40.10years;SD9.65years),andthey werepredominantlyfemales(n=146),Blacks(n=87),and hadatleastsomecollegeorassociatedegree(n=102). Mostoftheparents(n=150)hadadequatefunctional healthliteracy.Bodymassindex(BMI)wascalculatedas theweightinkilogramsdividedbytheheightinmeters squared.GrowthreferencechartsdevelopedbytheWorld HealthOrganizationBMIwereusedtocategorizeeach childintodifferentweightcategories.Morethanhalfof thechildren(n=86)wereoverweight/obese.Correlationsamongvariablesofinterestincludedinthe modelTable2showsthebivariatecorrelationsbetweenthe variablesofinterests.Thestrongestrelationshipwas foundbetweentheperceivedself-efficacywithpatientphysicianinteractionandsatisfactionwithSDM(r=0.59, P <0.001),whereparentsthatreportedgreaterperceived self-efficacyweremorelikelytoreportgreatersatisfaction withSDMthanparentswithlessperceivedself-efficacy. Parentalhealthliteracywassignificantlyassociatedwith satisfactionwithSDM,yetthemagnitudewassmall (r=0.19, P <0.05).SatisfactionwithSDMwassignificantlyassociatedwithasthmacontrol(r= Š 0.22, P <0.01), whereparentswithgreatersatisfactionwithSDMwere lesslikelytoreportpoorasthmacontrolinchildren. AsthmacontrolwassignificantlyassociatedwithasthmaspecificHRQoL(r=0.40, P <0.001).Childrenwithwell controlledstatusreportedbetterasthma-specificHRQoL comparedtochildrenwithpoorlycontrolledstatus.Gandhi etal.RespiratoryResearch 2013, 14 :26 Page4of10 http://respiratory-research.com/content/14/1/26

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MeasurementmodelTable3showsthemeasurementpartoftheSEM,includinginternalconsistentreliability(Cronbach ’ salpha) ofthefourlatentvariables,andfactorloadings( )for itemsassociatedwiththelatentvariables.Ingeneral,all itemsweresignificantlyassociatedwithcorresponding latentvariableswithacceptablelevelsoffactorloadings ( >0.4; P <0.001).Therangeoffactorloadingswas 0.46-0.83forperceivedself-efficacy,0.53-0.86forsatisfactionwithSDM,0.67-0.82forasthmacontrol,and 0.53-0.79forasthma-specificHRQoL.Theseresultswere consistentwiththefindingofCronbach ’ salpha,where thevalueswere0.91forperceivedself-efficacywith patient-physicianinteracti on,0.94forsatisfactionwith SDM,0.84forasthmacontrol,and0.87forasthmaspecificHRQoL.Pathanalysisforrelationshipsamongvariablesincluded inthestructuralmodelWefirsttestedthefullpathanalyticmodelwhichincludesallthehypothesizedvariables.Thefitofthefull modelwasdeemedsatisfactoryalthoughtherelationshipsbetweensomevariableswerenotstatisticallysignificant( P >0.05).Thepathsfromhealthliteracyto perceivedself-efficacywithpatient-physicianinteraction, fromperceivedself-efficacywithpatient-physicianinteractiontoasthmacontrolandasthma-specificHRQoL, andfromsatisfactionwithSDMtoasthma-specific HRQoLwerenotstatisticallysignificant(detailedresults availableuponrequest).Figure1showsthereducedpath analyticmodelwithstandardizedpathcoefficientsthat werestatisticallysignificant( P <0.05).Comparedtothe fullmodel,thereducedmodelimprovedthemodelfit slightly( 2(df)=1036.69(624);RMSEA(90%CI)=0.064 (0.057 – 0.071)). Table4showsthedirectandindirecteffectsamong variableofinterestsderivedfromthereducedpathanalyticmodelshowninFigure1.Asthma-specificHRQoL wassignificantlyassociatedwithasthmacontrolstatus, wherechildrenwithgoodasthmacontrolstatusreported higherasthma-specificHRQoLcomparedtothosewith poorasthmacontrol( =0.4, P <0.001).Parentswith higherhealthliteracyandgreaterperceivedself-efficacy withpatient-physicianinteractionhadhighersatisfaction Table1SamplecharacteristicsVariablesMean(SD) Childrencharacteristics Age(inyears)11.61(2.41) Gender Male59.38% Female40.63% Race White,non-Hispanic31.88% Black,non-Hispanic55.63% Hispanic/other12.50% Asthmacontrolstatus Goodcontrol48.13% Poorcontrol51.88% Baselinecomorbidconditions Zerocomorbidcondition35.63% >=1comorbidcondition64.38% Specificconditions Atopicdisease37.5% Attentiondeficithyperactivitydisorder/other learningdisability 10.63% Mentalhealthcondition3.13% Highbloodpressure1.88% Thyroiddisease1.25% Bornprematurely1.25% Other14.38% BodyMassIndex Severethinness/thinness2.5% Normal34.38% Overweight/obese53.75% Parentcharacteristics Age(inyears)40.10(9.65) Gender Male8.75% Female91.25% Race White,non-Hispanic38.75% Black,non-Hispanic54.38% Hispanic/other6.88% Education Lessthanhighschool14.38% Highschool/generaleducationaldevelopment21.88% Somecollege/associatedegree41.88% Collegedegree/somegradschool21.88% Familyincome#Lessthan10,00020.00% 10,000 – 29,99937.50% Table1Samplecharacteristics (Continued)30,000 – 59,99924.38% >$60,00015.63% Healthliteracy <=22(inadequateormarginalfunctional)6.26% >=23(adequatefunctional)93.75%SD:standarddeviation.#Duetomissingdata,thesevaluesmaynotaddupto100%.Gandhi etal.RespiratoryResearch 2013, 14 :26 Page5of10 http://respiratory-research.com/content/14/1/26

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withSDM( =0.38, P <0.05; =0.58, P <0.001,respectively).However,greaterperceivedself-efficacywith patient-physicianinteractionwasindirectlyassociated withhigherasthma-specificHRQoLthroughgreatersatisfactionwithSDMandbetterasthmacontrol( = Š 0.06, P <0.05).Inaddition,greaterperceivedself-efficacywith patient-physicianinteractionwasindirectlyassociated withwell-controlledasthmathroughgreatersatisfactionwithSDM( = Š 0.15, P <0.01).Greatersatisfaction withSDMwassignificantlyassociatedwithasthmacontrol,whereparentswithhighersatisfactionwithSDM reportedwellcontrolledasthmacomparedwiththosewith lowersatisfactionwithSDM( = Š 0.26, P <0.01).Finally, greatersatisfactionwithSDMwasindirectlyassociated withhigherasthma-specificHRQoLthroughbetterasthmacontrol( = Š 0.11, P <0.05).DiscussionTheprimarygoalofasthmatreatmentemphasizedin thenationalandinternationalasthmaguidelinesisto controlasthmasymptomsandpreventasthmaflares makingitimperativetoevaluateasthmacontrolstatus foreverypatient[9,10].Ourresults,reflectingandexpandingpreviousstudies[13-15],indicatethatgood asthmacontrolstatusisassociatedwithbetterHRQoL. WhilepreviousworkhasexaminedtheassociationbetweenasthmacontrolandHRQoLinchildren[15,38], thesestudiesdidnotexplicitlytestwhichparentalfactorsinfluenceasthmacontrolstatus,inturnaffecting asthma-specificHRQoL.Thepresentstudyshowshow theparentalfactorssuchashealthliteracy,satisfactionwithSDM,andperceivedself-efficacywithpatientphysicianinteractiondirectlyandindirectlyaffectasthma controlthroughdifferentpathways,whichinturn influencespediatricasthma-specificHRQoL.Notably, theassociationbetweenasthmacontrolandasthmaspecificHRQoLremainedstrongaftertakingintoaccounttheinfluenceofthesefactors.Understandingand accountingforthesefactorsmayhelppractitionersidentifypatientsatanincreasedriskofpoorasthmacontrol tobettermanagetheirasthmasymptomsandimprove asthma-specificHRQoL. Oneofthespecificaimsofthepresentstudywas toexaminehowparentalhealthliteracy,perceived self-efficacywithpatient-physicianinteractionandsatisfactionwithSDMcancontributetochildren ’ sasthma controlandasthma-specificHRQoL.Interestingly,we foundalackofassociationbetweenhealthliteracyand perceivedself-efficacywithpatient-physicianinteraction, whichisconsistentwithapreviousstudy[24],butincontrasttoanotherstudy[23].Thereasonsbehindthislack ofassociationmaybeconfoundedduetotheincreased self-confidenceinparentswhohaveestablishedalongtermopenandtrustingrelationshipwiththeirphysicians [39].Ontheotherhand,itispossiblethatperceivedselfefficacywithpatient-physicianinteractionmaybeexplainedbypersonalitytraits(e.g.,optimism),whichisnot influencedbyone ’ slevelofhealthliteracy.Lastly,wehad veryfewparentswithlowhealthliteracyandthatmay havelimitedourabilitytodetectsmall,butimportant relationshipsbetweenhealthliteracyandperceivedselfefficacywithpatient-physicianinteraction. Evidenceislimitedabouttherelationshipbetween healthliteracyandsatisfactionwithSDM.Somestudies reportedthatpatientswithlowerhealthliteracywere lesslikelytotakepartinthemedicaldecision-making process[22,40].Thepresentstudyextendstheprevious findings,showingthatparentswithhigherlevelsof healthliteracyhadgreatersatisfactionwithSDM.Itis plausiblethatparentswithhighliteracylevelswerelikely totakeanactiveroleandintensivelyengageintheshareddecisionprocess,leadingtoanincreaseintheirsatisfactionwithSDM.Designingappropriateinterventionsto improvehealthliteracylevels,particularlyasthma-relevant literacy,mayfosterthepatient-physiciancommunication, andincreasetheinvolvementofparentsintheSDM[22]. Theassociationbetweenself-efficacyandasthmaoutcomes,especiallyasthmacontrolandHRQoL,remains unclear.Whilethepresentstudyfoundthatperceived self-efficacywasnotdirectlyassociatedwithasthmacontrolandasthma-specificHRQoL,othershavepreviously notedthisassociation[25,27].Fromadesignperspective, thediscrepantfindingsmaybeduetothefactthatpreviousstudiesinvestigatedtheinfluenceofself-efficacyas Table2BivariatecorrelationsamongvariablesofinterestsVariableHealthliteracyPerceived self-efficacy Satisfactionwith shareddecision-making AsthmacontrolAsthma-specific HRQoL Healthliteracy1---Perceivedself-efficacy0.021--Satisfactionwithshareddecision-making0.19*0.59***1-Asthmacontrol 0.06 0.15 0.22**1Asthma-specificHRQoL 0.10 0.07 0.100.40***1HRQoL:health-relatedqualityoflife. p <0.05;** p <0.01;*** p <0.001.Gandhi etal.RespiratoryResearch 2013, 14 :26 Page6of10 http://respiratory-research.com/content/14/1/26

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Table3MeasurementmodelforlatentfactorsandindicatorvariablesLatentfactorandindicatorvariablesResponsescaleMean(SD)Factorloading, *** Perceivedself-efficacy Cronbach ’ salpha:0.91 1.ConfidentinabilitytogetaDr.topayattentiontowhatyousay1 – 5a4.44(0.81)0.71 2.Confidentinabilitytoknowwhatquestionstoask1 – 5a4.29(0.89)0.60 3.ConfidentinabilitytogetaDr.toanswerallquestions1 – 5a4.31(0.78)0.79 4.ConfidentinabilitytoaskDr.questionsaboutchiefconcern1 – 5a4.50(0.73)0.77 5.ConfidentinabilitytomakemostofvisitwithDr.1 – 5a4.44(0.77)0.80 6.ConfidentinabilitytogetDr.takechiefconcernseriously1 – 5a4.44(0.77)0.83 7.ConfidentinabilitytounderstandwhatDr.tellsyou1 – 5a4.56(0.64)0.46 8.ConfidentinabilitytogetaDr.todosomethingaboutconcern1 – 5a4.44(0.69)0.83 1.ConfidentinabilitytoexplainchiefhealthconcerntoDr.1 – 5a4.43(0.77)0.63 2.ConfidentinabilitytoaskDr.formoreinformation1 – 5a4.54(0.64)0.67 Satisfactionwithshareddecision-making Cronbach ’ salpha:0.94 1.Dr.madeitclearthatadecisionneedstobemade1 – 6b5.04(1.12)0.53 2.Dr.wantedtoknowexactlyhowIwantedtobeinvolved1 – 6b5.01(1.09)0.74 3.Dr.toldmetherearedifferentoptionfortreatment1 – 6b4.86(1.29)0.70 4.Dr.explainedadv/disadvoftreatmentoptions1 – 6b4.94(1.18)0.85 5.Dr.helpedmetounderstandallinfo1 – 6b5.18(1.02)0.78 6.Dr.askedmewhatoptionIprefer1 – 6b4.81(1.32)0.80 7.Dr.andIweightoptions1 – 6b4.75(1.37)0.84 8.Dr.andIselectedatreatmentoptiontogether1 – 6b4.68(1.44)0.86 9.Dr.andIreachedanagreementonhowtoproceed1 – 6b5.05(1.08)0.86 Asthmacontrol Cronbach ’ salpha:0.84 1.Recodeofitem:numberofdayschildhassymptoms1 – 4c1.49(0.87)0.67 2.Recodeofitem:numberofdayschildhadtouserescueasthmamedicine1 – 4c1.31(0.65)0.71 3.Recodeofitem:numberofdayschildhadanasthmaattack1 – 4c1.58(0.90)0.82 4.Recodeofitem:howmuchdidchild ’ sasthmalimitactivities1 – 4c1.40(0.75)0.72 5.Recodeofitem:howmanynightsdidasthmawakehim/herup1 – 3d1.28(0.54)0.71 Asthma-specificHRQoL Cronbach ’ salpha:0.87 3.Feltscaredbecauseofbreathing1 – 5e2.35(1.13)0.53 4.Chestfelttightbecauseofasthma1 – 5e2.50(1.26)0.70 5.Feltwheezy1 – 5e2.99(1.27)0.73 6.Troublebreathing1 – 5e3.07(1.26)0.79 7.Troublesleeping1 – 5e2.42(1.22)0.59 8.Hardtoplaysportsorexercise1 – 5e2.79(1.43)0.65 9.Hardtotakeadeepbreath1 – 5e2.48(1.24)0.68 10.Asthmabotheredme1 – 5e2.95(1.37)0.73SD:standarddeviation;HRQoL:health-relatedqualityoflife. *** p <0.001.a(1)Notatall;(5)Verymuch.b(1)Completelydisagree;(6)Completelyagree.c(1)Mildintermittent;(4)Severepersistent.d(1)Mildintermittent;(3)Moderatepersistent.e(1)Never;(5)Almostalways.Gandhi etal.RespiratoryResearch 2013, 14 :26 Page7of10 http://respiratory-research.com/content/14/1/26

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partofthepsychosocialcopingresource[41]orasselfefficacyonHRQoL[27];instead,ourstudytestedtheinfluenceofperceivedself-efficacywithpatient-physician interactiononbothasthmacontrolandasthma-specific HRQoL. Thisstudyidentifiedseveralimportantpathwaysinvolvedingoodasthmacontrolandasthma-specificHRQoL. Thefindingshighlighttheneedforappropriateinterventionstoimproveasthmacontrolandasthma-specific HRQoLinchildrenthroughtheneedsandstrengthsof theirparents.Higherperceivedself-efficacywithpatientphysicianinteractionwouldbeindirectlyassociatedwith goodasthmacontrolthroughthesatisfactionwithshared decision-making.Thisimpliesthatifclinicianscanimprovethepatient-doctorinteractionsthroughassuringthat patientsunderstandtheasthmatreatmentplanandare satisfiedwiththeinteractionprocess,thelikelihoodof achievinggoodasthmacontrolishigh.Ontheotherhand, higherperceivedself-efficacywasindirectlyassociatedwith betterasthma-specificHRQoLthroughsatisfactionwith 0.38*(2.1) 0.58***(4.83) -0.26**(-2.63) 0.40***(3.64) Perceived self-efficacy Satisfaction with shared decision-making Asthma control Asthma-specific HRQoL Health literacy Figure1 Pathanalysisfortherelationshipsbetweenhealthliteracy,perceivedself-efficacy,satisfactionwithshareddecision-making, asthmacontrol,andasthma-specificHRQoL. HRQoL:health-relatedqualityoflife.Dottedlinesindicatestatisticallynon-significantpathways andsolidlinesindicatestatisticallysignificantpathways.Valuesrepresentstandardizedparameterestimatesandt-values(inparentheses).M odel fitforthemodelincludessolidlinesonly: 2(degreesoffreedom):1036.69(624),andRMSEA(90%CI):0.064(0.057 – 0.071).* p <0.05;** p <0.01; *** p <0.001. Table4Direct,indirect,andtotaleffectsamongvariablesofinterestsLatentvariables Standardizedparameterestimates andstandarderror(inparentheses) Directeffects Healthliteracy satisfactionwithshareddecision-making0.38*(0.18) Perceivedself-efficacy satisfactionwithshareddecision-making0.58***(0.12) Satisfactionwithshareddecision-making asthmacontrol 0.26**(0.10) Asthmacontrol asthma-specificHRQoL0.40***(0.11) Indirecteffects Perceivedself-efficacy satisfactionwithshareddecision-making asthmacontrol 0.15**(0.06) Perceivedself-efficacy Satisfactionwithshareddecision-making asthma control asthma-specificHRQoL 0.06**(0.03) Satisfactionwithshareddecision-making asthmacontrol asthma-specificHRQoL 0.11*(0.05) Totaleffects Healthliteracy perceivedself-efficacy satisfactionwithshareddecision-making0.48*(0.21) Perceivedself-efficacy satisfactionwithshareddecision-making0.58***(0.12) Perceivedself-efficacy satisfactionwithshareddecision-making asthmacontrol 0.15**(0.06) Satisfactionwithshareddecision-making asthmacontrol 0.26**(0.10) Perceivedself-efficacy Satisfactionwithshareddecision-making asthma control asthma-specificHRQoL 0.06*(0.03) Satisfactionwithshareddecision-making asthmacontrol asthma-specificHRQoL 0.11*(0.05) Asthmacontrol asthma-specificHRQoL0.40***(0.11)HRQoL:health-relatedqualityoflife. Valuesrepresentstandardizedparameterestimatesandstandarderror(inparentheses). p <0.05;** p <0.01;*** p <0.001.Gandhi etal.RespiratoryResearch 2013, 14 :26 Page8of10 http://respiratory-research.com/content/14/1/26

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SDMandasthmacontrol.Itthusseemsappropriatethat interventionstargetedatincreasingperceivedself-efficacy and/orsatisfactionwithSDMwillincreasethelikelihood ofimprovingasthmaoutcomes. Thestudyisnotwithoutlimitations.Weutilizeda cross-sectionalstudydesigntoinvestigatetheinterrelationshipsamongvariables.Thislimitsourabilitytointerpretthecausalrelationshipsamongthesevariables. Ourpathanalysisdid,however,allowustoestablish whichofthepotentialmediatorvariablesweremostimportantinexplainingtheoverallassociationwiththe asthmaoutcomes.Thepathanalysisthatweusedinthis studyprovidesevidencewhethertheobserveddatawere consistentwithapriorihypothesesbasedonevidence availablefromseveralstudies.Werecognizethatthe causalityincross-sectionalstudiescanonlybespeculatedandbeacceptedwithcaution;longitudinalstudies areneededtoexaminethoseassociations.Second,participantswererecruitedfromfivepediatricclinicsofa singleuniversitymedicalcenter,whichmaylimitthe generalizabilityofthesefindingstootherpopulations. Third,wedidnotdistinguishtheroleofparentalhealth literacyonasthma-specificoutcomesinchildrencomparedtoadolescents.Oftentimesadolescentsaremore mature,havedifferentcognitiveabilitiesandaremore responsiblethanchildrenwhichmaypotentiallyinfluencetheirroleinthedecisionmakingprocess[42].Futurestudiesshouldinvestigatetheroleofhealthliteracy inadolescentsanditsrelationshipwithself-efficacy,satisfactionwithSDM,andasthmaoutcomesandhowit differstotheroleofparentalhealthliteracyinchildren forthesaidrelationships.Fourth,werelyonparentreporttocollectchild ’ sasthmacontrolstatusbecauseour clinicalexperienceinformsusthatparentswouldbetter understandandrecognizethetypesofmedicationthan childrendid.Nevertheless,previousstudieshaveshown thatthediscrepancyinparentandchildreportswere notdifferent[43,44];andparentsandchildrentendto overstateasthmamedicationadherencecomparedtothe useofasthmainhalercanisterweightchecks[44]and electroniccanistermeasuresthatrecordeddailyadherencethroughamicrochip[43].Moreresearchisneeded totesttheaccuracyanddiscrepancyinchildself-orparentproxy-reportofthemedicationuse.Lastly,thesmall numberofrespondentsmayhaveinfluencedthemodel fitinthepathanalyses.Nevertheless,weusedprocedures notedtooptimizeuseofSEMproceduresinstudieswith smallsamplesizes[36,45].ConclusionChildren ’ sasthmacontrolstatusinfluencedtheirasthma-specificHRQoL.However,severalparentalfactors contributingtoasthmacontrolindirectlyaffectedasthma-specificHRQoL.Parentswithgreaterperceivedselfefficacywithpatient-physicianinteractionweremore likelytobesatisfiedwithSDM,whichinturnwasassociatedwithbetterasthmacontrol,leadingtobetter asthma-specificHRQoL.Interventionstudiesfocusing onimprovingself-efficacyandsatisfactionwithSDMare importanttopursueforbetterimprovingasthmacontrol andultimatelyasthma-specificHRQoL.Abbreviations CI:Confidenceinterval;HRQoL:Health-relatedqualityoflife;NAEPP:National asthmaeducationandpreventionprogram;NIH:Nationalinstituteofhealth; PROMIS:Patient-reportedoutcomesmeasurementinformationsystem; RMSEA:Rootmeansquareerrorofapproximation;SDM:Shareddecisionmaking;SEM:Structuralequationmodeling;S-TOFHLA:Shorttestof functionalhealthliteracyinadults;UF:UniversityofFlorida; 2:Chi-square; :Factorloading. Competinginterests Theauthorsdeclarethattheyhavenocompetinginterests. Authors ’ contributions DAD,DAR,EAS,andICHdesignedthestudy.KMKandLATconducteddata collection.PKG,KMK,andICHanalyzedthedataandinterpretedtheresults. PKG,KMK,andICHwrotethemanuscript.LAT,DAD,DAR,andEAScritically revisedthemanuscript.EASsupervisedtheentirestudy.Allauthorsreadand approvedthefinalmanuscript. Acknowledgement ThisworkwassupportedbythegrantsfromNIHK23HD057146(ICH)and NIHU01AR052181(DAD,ICH,EAS,andLAT). TheauthorsthankShih-WenHuang,MD,KathleenRyan,MD,andElizabeth LeFave,ARNPforscreeningpatienteligibility,andTiffanyBrown,RN,Heidi Saliba,BA,CamilleJackson,MPH,andMaryAnderson,BS,forassistingdata collection. Fundingsources ThisworkwassupportedinpartbytheNationalInstitutesofHealth(NIH) K23HD057146(ICH)andU01AR052181-06(LAT,DAD,EAS,andICH). Authordetails1DepartmentofPharmacyPractice,SchoolofPharmacy,SouthCollege, Knoxville,TN,USA.2DepartmentofHealthOutcomesandPolicy,Collegeof Medicine,UniversityofFlorida,Gainesville,FL,USA.3Departmentof Pediatrics,CollegeofMedicine,UniversityofFlorida,Gainesville,FL,USA.4DepartmentofMedicine,SchoolofMedicine,UniversityofNorthCarolinaChapelHill,ChapelHill,NC,USA.5OutcomesResearch,UnitedBioSource Corporation,Bethesda,MD,USA.6InstituteforChildHealthPolicy,Collegeof Medicine,UniversityofFlorida,Gainesville,FL,USA. Received:11November2012Accepted:19February2013 Published:23February2013 References1.LuysterFS,TeodorescuM,BleeckerE,BusseW,CalhounW,CastroM,Chung KF,ErzurumS,IsraelE,StrolloPJ,WenzelSE: Sleepqualityandasthma controlandqualityoflifeinnon-severeandsevereasthma. SleepBreath 2012, 16 (4):1129 – 37. 2.AkinbamiLJ,MoormanJE,LiuX: Asthmaprevalence,healthcareuse,and mortality:UnitedStates,2005 – 2009. 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Pediatrics 2009, 124 (3):S265 – S274. 43.BenderBG,BartlettSJ,RandCS,TurnerC,WamboldtFS,ZhangL: Impactof interviewmodeonaccuracyofchildandparentreportofadherence withasthma-controllermedication. Pediatrics 2007, 120 (3):e471 – e477. 44.BenderB,WamboldtFS,O ’ ConnorSL,RandC,SzeflerS,MilgromH, WamboldtMZ: Measurementofchildren ’ sasthmamedicationadherence byself-report,motherreport,canisterweight,andDoserCT. AnnAllergy AsthmaImmunol 2000, 85: 416 – 421. 45.TanakaJS: “ Howbigisbigenough? ” Samplesizeandgoodnessoffit instructuralequationmodelswithlatentvariables. ChildDev 1987, 58: 134 – 146.doi:10.1186/1465-9921-14-26 Citethisarticleas: Gandhi etal. : Exploringfactorsinfluencingasthma controlandasthma-specifichealth-relatedqualityoflifeamong children. RespiratoryResearch 2013 14 :26.Gandhi etal.RespiratoryResearch 2013, 14 :26 Page10of10 http://respiratory-research.com/content/14/1/26