Development and psychometric properties of knee-specific body-perception questionnaire in

15 Pages·2017·1.42 MB·English

RESEARCHARTICLE
Development and psychometric properties of
knee-specific body-perception questionnaire
in people with knee osteoarthritis: The
Fremantle Knee Awareness Questionnaire
TomohikoNishigami1*,AkiraMibu2,KatsuyoshiTanaka2,YuhYamashita3,EijiYamada4,
BenedictM.Wand5,MarkJ.Catley6,TashaR.Stanton6,7,G.LorimerMoseley6,7
1 DepartmentofNursingandPhysicalTherapy,KonanWoman’sUniversity,Kobe,Hyogo,Japan,
2 DepartmentofRehabilitation,TanabeOrthopaedics,Osaka,Osaka,Japan,3 Departmentof
a1111111111 Rehabilitation,MorinagaOrthopedicClinic,Saga,Saga,Japan,4 JointSurgeryCentre,KaiseiHospital,
a1111111111 Sakaide,Kagawa,Japan,5 TheSchoolofPhysiotherapy,TheUniversityofNotreDameAustralia,
a1111111111 Fremantle,WA,Australia,6 SansomInstituteforHealthResearch,UniversityofSouthAustralia,SA,
a1111111111 Australia,7 NeuroscienceResearchAustralia,Sydney,NSW,Australia
a1111111111
*[email protected]
Abstract
OPENACCESS
Citation:NishigamiT,MibuA,TanakaK,
Background
YamashitaY,YamadaE,WandBM,etal.(2017)
Developmentandpsychometricpropertiesofknee- Recentsystematicreviewshavedemonstratedthatpainassociatedwithkneeosteoarthritis
specificbody-perceptionquestionnaireinpeople (OA)isacomplexphenomenonthatinvolvesvariouscontributors.PeoplewithkneeOA
withkneeosteoarthritis:TheFremantleKnee
exhibitsymptomsofimpairedbody-perception,includingreducedtactileacuity,impairments
AwarenessQuestionnaire.PLoSONE12(6):
e0179225.https://doi.org/10.1371/journal. inlimblateralityrecognition,anddegradedproprioceptiveacuity.TheFremantleBack
pone.0179225 AwarenessQuestionnaire(FreBAQ)wasdevelopedtoassessbody-perceptionspecificto
Editor:MasahikoSumitani,TokaiDaigaku,JAPAN thebackinpeoplewithchroniclowbackpain.Theaimofthisstudywastodevelopand
assessthepsychometricpropertiesofaknee-specificversionoftheFreBAQ-J(FreKAQ-J),
Received:April11,2017
determinewhetherpeoplewithkneepainexperienceperceptualimpairmentsandinvesti-
Accepted:May25,2017
gatetherelationshipbetweendisturbedself-perceptionandclinicalstatus.
Published:June26,2017
Copyright:©2017Nishigamietal.Thisisanopen Methods
accessarticledistributedunderthetermsofthe
Sixty-fivepeoplewithkneeOAcompletedtheFreKAQ-J.Asubsetoftheparticipantscom-
CreativeCommonsAttributionLicense,which
permitsunrestricteduse,distribution,and pletedtheFreKAQ-Jagaintwo-weekslater.Raschanalysiswasusedtoassessitemorder,
reproductioninanymedium,providedtheoriginal targeting,categoryordering,unidimensionality,personfit,internalconsistency,anddifferen-
authorandsourcearecredited.
tialitemfunctioning.Validitywasinvestigatedbyexaminingtherelationshipbetweenthe
DataAvailabilityStatement:Dataareavailable FreKAQ-Jandclinicalvaluables.
fromthecorrespondingauthorsbecausethedata
containsinformationthatcouldbeusedtoidentify
Results
studyparticipants.
TheFreKAQ-Jhadacceptableinternalconsistency,unidimensionality,goodtest-retestreli-
Funding:Theauthorsreceivednospecificfunding
forthiswork. ability,andwasfunctionalonthecategoryratingscale.TheFreKAQ-Jwassignificantlycor-
relatedwithpaininmotion,disability,pain-relatedcatastrophizing,fearofmovement,and
Competinginterests:Theauthorshavedeclared
thatnocompetinginterestsexist. anxietysymptomatology.
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Knee-specificbody-perceptionquestionnaire
Conclusions
WedevelopedFreKAQ-JbymodifyingtheFreBAQ-J.TheFreKAQ-JfitstheRaschmea-
surementmodelwellandissuitableforuseinpeoplewithkneeOA.Alteredbodyperception
maybeworthevaluatingwhenmanagingpeoplewithkneeOA.
Introduction
Kneeosteoarthritis(OA)isassociatedwithavarietyofsymptoms,suchaspain,stiffnessand
lossoffunction[1].Whilestructuralabnormalitieshavebeenrelatedtopaininpeoplewith
kneeOA,therelationshipismodest[2]andsuchabnormalitiesareoftenobservedinpeople
withoutkneepain[3].Recentsystematicreviewshavedemonstratedthatpainassociatedwith
kneeOAisacomplexphenomenonthatinvolvesvariouscontributors,includinglifestyle,cog-
nitivefactorsandperipheral/centralsensitization[4–7].Similartootherchronicpaincondi-
tions,suchaslowbackpain[8–13]andcomplexregionalpainsyndrome[14–16],peoplewith
chronickneeOAexhibitsymptomsofimpairedbody-perception,includingreducedtactile
acuity[17],impairmentsinlimblateralityrecognition[18],anddegradedproprioceptiveacu-
ity[19,20].Furthermore,neuroimagingstudiesofpeoplewithchronicOAdemonstratemor-
phologicalandfunctionalchangesofcorticalareassuchasgraymatterloss[21],disrupted
whole-brainmorphologicalstructure[22],functionalreorganizationofthedefaultmodenet-
work[23]andreorganizationofthemotorcortex[24].Toourknowledge,therehasbeenno
attempttoexplicitlydetermineifalteredself-perceptionisafeatureofchronickneeOAorto
investigateifalteredself-perceptionisrelatedtotheseverityoftheclinicalcondition.
Recently,theFremantleBackAwarenessQuestionnaire(FreBAQ)wasdevelopedtoassess
body-perceptionspecifictothebackinpeoplewithchroniclowbackpain[25]andithassince
beentranslatedintoJapanese;theFreBAQ-J[26].TheFreBAQiscomposedofnineitems
investigatingneglect-likesymptoms,reducedproprioceptiveacuity,andissuesofbodyshape
andsize.TheFreBAQscoreisassociatedwithclinicalvariablesincludingpainintensity,dura-
tionofpain,disability,andcatastrophizingandappearstohaveacceptablepsychometricprop-
erties[25–27].WewereinterestedinexaminingwhetherpeoplewithchronickneeOAalso
endorsedsymptomsconsistentwithimpairedself-perceptionandwhetherdisturbedself-per-
ceptionisrelatedtoclinicalstatus.Therefore,theaimsofthisstudywereto:
1. Developandassessthepsychometricpropertiesofaknee-specificversionoftheFreBAQ-J.
2. Determinewhetherpeoplewithchronickneepainexperienceperceptualimpairments.
3. Investigatetherelationshipbetweendisturbedself-perceptionandclinicalstatus.
Methods
EthicalapprovalwasobtainedfromtheinstitutionalethicscommitteeofKonanWoman’s
University.Writteninformedconsentwasobtainedfromallsubjectspriortothestudy.The
studywasconductedincompliancewiththeDeclarationofHelsinki.
Participants
Sixty-fivepeoplewithkneeOAwererecruitedconsecutivelyfromtwoorthopedicclinicsand
oneJointSurgeryCenter.Allpatientswerescreenedandrecruitedbymedicaldoctor.Inclu-
sioncriteriawereadiagnosisofkneeOAbasedonclinicalguidelines(AmericanCollegeof
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Knee-specificbody-perceptionquestionnaire
Rheumatology)[28],kneepainfor>3months(aschronicpainisdefinedaspersistentor
recurrentpainlastinglongerthan3months),withaKellgren-Lawrence(KL)scoreof2or
moreandagebetween40and85years.Theexclusioncriteriaweretotalkneearthroplasty,
seriouspathologies(unhealedfractures,tumors,acutetrauma,orseriousillness),neurological
findings(muscleweakness,lossofsensationorreflexes),anddiagnosedpsychiatricdisorders.
AnequalnumberofhealthyindividualswithnohistoryofkneeOAandwhomatchedtheage
andgenderoftheenrolledpatientswererecruitedascontrols.
DevelopmentoftheFremantleKneeAwarenessQuestionnaire
(FreKAQ-J)
TheFreBAQ-Jwasinitiallydevelopedusingaforward–backwardtranslationmethod[26].To
developakneespecificversion,theFreKAQ-J,theJapanesecharacterfor‘knee’wassubsti-
tutedfor‘back’.Wedeemeditem9oftheFreBAQ-J(Mybackfeelslopsided)toberedundant
asfeelingsofasymmetrydonotapplytotheknee.Weadaptedtheitemtoreflectaperceptual
differencebetweensides.Thedirecttranslationofitem9,fromJapanesetoEnglish,was“My
kneefeelsdifferentwithrightandleft(Onesidefeelsdullorfat)”.
Procedure
Demographicdata(age,gender,height,weight)wereassessedinallparticipants,andpain
duration,painintensity,pain-relatedcatastrophizing,fearofmovement,anxiety,depressive
symptomatologyandkneepain-relateddisabilitywereevaluatedintheparticipantswithknee
OA.Painintensityatrestandduringmovementweremeasuredusinga0–100visualanalog
scaleanchoredatleftwith“0=nopain”andatrightwith“100=unbearablepain”[29,30,31].
Pain-relatedcatastrophizingwasmeasuredusingtheJapaneseversionofthePainCatastro-
phizingScale(PCS)[32,33]andpain-relatedfearwasassessedusingtheJapaneseversionof
theTampaScaleofKinesiophobia(TSK)[34,35].Weevaluatedanxietyanddepressionwith
theJapaneseversionoftheHospitalAnxietyandDepressionScale(HADS),whichconsistsof
sevenanxietyandsevendepressionitems,fromwhichseparateanxietyanddepressionscores
arecalculated[36–38].FunctionaldisabilitywasmeasuredusingtheJapanese-validatedver-
sionofOxfordKneeScore(OKS)(0–48;higherscoresindicatemorefunctionalability)for
patientswithkneeOA[39,40].Inaddition,alloftheparticipantscompletedtheFreKAQ-J.
TheinstructionsusedforthecontrolparticipantswhenfillingouttheFreKAQ-Jread‘please
indicatethedegreetowhichyourkneefeelsthiswaytoday’.
PsychometricassessmentoftheFreKAQ-J
OnlyparticipantswithkneeOAwasusedforRaschanalysis.WeusedRaschanalysistoana-
lyzethepsychometricpropertiesoftheFreKAQ-J,followingthesameprocedureusedinour
previousstudy[26].RaschanalysisallowsustocomparetheordinalFreKAQ-Jdatatoaprob-
abilisticmathematicalmodelthatisbasedonfundamentalprinciplesofmeasurement[41–43].
Appliedhere,themodelassumesthatapersonwithcomparativelyfrequentperceptual
impairmentismorelikelytoendorseanyoftheFreKAQ-Jitemsandthelikelihoodofanitem
thatreflectscomparativelylittleperceptualimpairmentismorelikelytobeendorsedbyevery-
one.WeusedWinstepssoftware(v3.90.2,Chicago,Illinois)toanalyzethefollowing:
Itemorder. WhilealltheFreKAQ-JitemssharethesameLikertscale,theyarenot
endorsedtothesameextentbythesample.Thatis,someitemsarerelativelyhardertoendorse
becausetheyreflectexperiencesthataremorelikelytobeperceivedbyonlythosewithhigh
perceptualimpairment.RecentevaluationsoftheFreBAQ[27]foundtheitemsdifferedin
regardtoendorsabilityandthehierarchalorderoftheitemssupportedtheunderlying
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theoreticalconstructofperceptualimpairment,thusprovidingevidenceofvalidity[27].Here,
weassessedtheitemorderthroughananalysisoftherelativeendorsabilitymeasuresofthe
items.
Differentialtestfunctioning. DifferentialtestfunctioningcouldassesswhetherkneeOA
patientsusingtheFreKAQ-JandchroniclowbackpainpatientsusingtheFreBAQ-J[26]isa
similarmanner.Differentialtestfunctioningwasexploredifanitemyieldedasignificantdif-
ferenceofgreaterthan0.5logitsbetweensamples.
Targeting. TargetingreferstohowwelltheFreKAQ-Jitemstargetedtheparticipants.
Raschanalysisisaprobabilisticmodelthat,inthisinstance,assumespeoplewithgreaterper-
ceptualdisturbancewillbemoreagreeablewiththeFreKAQ-Jitemsthanthosewithlesserper-
ceptualdisturbanceanditemsindicativeofgreaterdisturbancearelessendorsablethanthose
indicativeoflesserdisturbance.Thus,ascaleisconsideredtotargetthesamplewellwhenthe
averageagreeabilityofthesampleissimilartotheaverageendorsiblityoftheitemswithis
anchoredat0logitsbytheRaschanalysissoftware.Weevaluatedtargetingbyvisualinspection
ofthedistributionofpersonanditemthresholdsandconsiderationofthesummarystatistics.
Wealsoconsideredthepresenceoffloorandceilingeffects.
Categoryorder. WeassessedcategoryordertoensuretheLikertscalefunctionedas
expected.TheFreKAQ-Jhasfiveresponsecategories(0=Never,1=Rarely,2=Occasionally,
3=Often,4=Always).Categoryprobabilitycurves,andaveragemeasureandcategoryfitsta-
tistics(infitandoutfit)wereusedtoexploreratingscalefunctioning.Ifadisorderedthreshold
isfound,theratingscalecollapses.Fitstatisticsarerecommendedtobebetween0.6and1.4
[44,45].Moreover,inawell-functioningratingscale,eachcurvehasadistinctpeakand4
clearthresholdsthatrepresentthepointatwhichthelikelihoodofendorsingonecategoryis
equaltothatofendorsingthenext.Disorderedthresholdscanoccurifacategoryisunderuti-
lizedorrespondentsusethecategoriesinanunexpectedmanner(eg,respondentscannotdif-
ferentiatebetweenthecategories).
Unidimensionality. WeintendtosummatetheFreKAQ-Jtoprovideanoverallmeasure
ofperceptualimpairment.Individualitemsshouldshareincommonthisunidimensionalcon-
structyetbesufficientlydifferenttowarranttheirinclusion.Assessmentoffitevaluatesunidi-
mensionalitybyidentifyingitemsthatfunctionunexpectedlyandtheprincipalcomponent
analysisofresiduals(PCA)identifiesunexpectedclustersofitemssuggestiveofasecondary
dimensionthatcouldthreatenmeasurementoftheprimarydimension.Excessivelylargefit
residuals(>1.4logits)indicatealargedifferencebetweentheexpectedandobservedperfor-
manceofanitem[46]andmayindicatethattheitemisassessingaconstructotherthanthe
intendedconstruct.Fitstatisticsarechi-squarebasedandarereportedasmean-squares(in
logits),withanexpectedvalueof1logit.Excessivelysmallfitresiduals(<0.6logits)identify
itemsthatbehavetoopredictably[46].Wecomparedbothinfit(information-weighted)and
outfit(outlier-sensitive)statisticsandinspectedtheitemcharacteristiccurvesofmisfitting
itemstodeterminehowtheybehavedforparticipantsofdifferingagreeability.ThePCAresid-
ualcorrelationmatrixwasvisuallyinspectedtoidentifyclustersofitemsthatwouldbesugges-
tiveofaseconddimension.Aneigenvaluegreaterthan2.0forthePCAofresidualssuggestsa
seconddimension[47].Responsedependencybetweentheitemswasexaminedbyinspecting
theresidualcorrelationmatrix[48]forpairsofitemswithcorrelationsexceeding0.4[49,50].
Personfit. Participantswithoutfitresidualsgreaterthan1.5logitswereexaminedto
determinethereasonforpoorfit[51].Theywerecomparedwiththosewhofitthemodel
usingFisher’sexacttest[52]ofsignificance(forgender)ortheMann-WhitneyUtest(forage,
painintensity,paindurationdisabilityandFreKAQ-J).Responsestringsofmisfittingpartici-
pantswereanalyzedtoidentifypatternsintheirresponses.
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Internalconsistency. WinstepsprovidesapersonreliabilityindexandCronbach’salpha
asindicatorsofinternalconsistency[53]andbothshouldexceed0.7[48].Aminimumvalue
of0.7issuggestedforgroupuse,andaminimumof0.85issuggestedforindividualuse[48].
Differentialitemfunctioning(DIF). Itemsshouldfunctioninasimilarmannerforall
peopleofsimilarlevelsofagreeability.WeassessedforDIFacross5subgroups:gender,age
((cid:20)65,>65years),painduringmotion((cid:20)50,>50mm),painduration((cid:20)1,>1years)anddis-
ability(mediansplit;(cid:20)33,>33).DIFwastestedusingaMantel–Haenszelchi-squaretestwith
significancesetatp=0.01foreachitem.Itembiaswasexploredifanitemyieldedasignificant
differenceofgreaterthan0.5logitsbetweensubgroups[54].
Test-retestreliability
FreKAQ-Jreliabilitywasassessedusingscoresobtainedfromasecondroundofthequestion-
naireadministeredwithin2weeksofthefirstquestionnairecompletion.Weonlyassessed
test-retestreliabilityinoutpatientstominimizetheeffectoftreatmentonclinicalstatus.An
intraclasscorrelationcoefficient(ICC)2-waymixedmodelwithabsoluteagreementwasused
todeterminemeasurementreliability.ICCvalues<0.40wereconsideredtoindicatepoorreli-
ability,0.40–0.75fairtogoodreliability,and0.75–1.00excellentreliability[55].
Relationshiptoclinicalstatus
Comparisonsbetweenthepatientsandthecontrolgroup,andthecorrelationanalysiswere
evaluatedusingtheStatisticalPackageforSocialSciencesVersion22.0(IBMSPSSStatisticsfor
MAC,Version22.0.Armonk,NY:IBMCorp.).Datadistributionwastestedforhomoscedas-
ticityusingtheKolmogorov-Smirnovtest.Age,height,weightandFreKAQ-J(fordiscrimina-
tivevalidity)werecomparedbetweenthekneeOAgroupandthecontrolgroupusingStudent
t-test.GenderwascomparedbetweenthekneeOAgroupandthecontrolgroupusingFisher
exacttest[52].Pvaluesoflessthan0.05wereconsideredstatisticallysignificant.
Aseriesofunivariatecorrelationswasperformedexaminingtherelationshipsbetweenthe
FreKAQ-Jtotalrawordinallevelscoresand:durationofpain,painintensity,disability,pain
catastrophizing,kinesiophobia,anxiety,anddepressioninthekneeOAgroup.Thesecorrela-
tionswereinvestigatedwithSpearman’scorrelationcoefficient.Weadjustedalphato0.007
becauseweundertooksevenseparateanalyses.
Results
Allparticipantscompletedallaspectsofthisstudy.Bothgroupcharacteristicsaresummarized
inTable1.Table2describesthefrequencyofresponsesforeachiteminthekneeOAgroup.
PsychometricassessmentoftheFreKAQ-J
Itemorder. Fig1showstheitemorderingandtherelationshipbetweenFreKAQ-Jitems
andpersonlogitratings.Theitemorderingisalsoevidentfromtheitemendorsabilitythresh-
oldspresentedinTable3.
Differentialtestfunctioning. Thedifferentialtestfunctioningresults(Fig2)supported
thisfindingbyshowingkneeOApatientsusedtheFreKAQ-Jinasimilarmannertochronic
lowbackpainpatientsusingtheFreBAQ-J.Itemsattheextremitiesofthescalewerestable
withsomedisorderinginthemiddleitems.
Targeting. Participantswithlowlevelsofdisturbedbodyperceptionwerenottargeted
wellbytheFreKAQ-J.Theaveragepersonendorsabilitywas-0.92logits(standarddeviation
(SD)1.34,range-3.61to3.12)whereasdefaultitemendorsabilityaverage=0logits(SD0.57,
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Table1. Demographicandclinicalinformation. OKS:OxfordKneeScore,PCS:PainCatastrophizing
Scale,TSK:TampaScaleofKinesiophobia,HADS:HospitalAnxietyandDepressionScale.
Characteristics KneeOA(n=65) Control(n=65)
Mean(SD)orN(%) Mean(SD)orN(%)
Demographicinformation
Gender(female) 50(76.9%) 50(76.9%)
Age(years) 68.5(9.1) 66.7(7.2)
Height(cm) 157.1(7.1) 158.2(7.6)
Weight(kg) 59.4(10.1) 56.9(9.2)
Bodymassindex 24.0(3.5) 22.6(2.6)
Clinicalstatus
SingleorbilateralkneeOA(single) 51(78.4%)
Durationofpainintensity(month) 57.7(88.4)
Painintensity
Rest 19.6(21.7)
Motion 43.5(24.1)
OKS 31.4(9.8)
Catastrophization(PCS) 24.4(12.6)
Kinesiophobia(TSK) 39.9(5.7)
Anxiety(HADS) 5.4(3.1)
Depression(HADS) 5.6(2.6)
FreKAQ-J 12.4(7.6) 3.4(4.4)
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range-1.21to0.73).Thatpersonagreeabilitywasshiftedtotheleftwhencomparedwithitem
endorsabilityindicatesthatthequestionnairebettertargetsthosewithhigherlevelsofdistur-
bancethanthosewithlowerlevelsofdisturbance.Item9wastheeasiestitemforparticipants
toendorse.Item8wasthemostdifficultitemtoendorse.Onlytwoparticipants(3.0%)scored
zeroforallitems;noparticipantsscoredfullpointsonallitems.
Table2. FrequencyofresponsestoeachitemoftheFreKAQ-J.
Item Never Rarely Occasionally Often Always Median Mean
N(%) N(%) N(%) N(%) N(%) (SD)
1.Ifeellikemykneeisnotpartofmyownbody 25 20 9(13.8) 8(12.3) 3(4.6) 1 1.1
(38.5) (30.8) (1.1)
2.TomovemykneethewayIwantto,IfeellikeIhavetoconcentrateallmy 14 18 13(20.0) 11 9(13.8) 2 1.7
nervesthere (21.5) (27.7) (16.9) (1.3)
3.SometimesIfeellikemykneemoveswithoutanyconnectiontowhatI 29 17 11(16.9) 7(10.8) 1(1.5) 1 0.9
intendittodo (44.6) (26.2) (1.0)
4.Whenperformingactivitiesofdailyliving(housework,work,etc.),Idonot 25 19 10(15.4) 9(13.8) 2(3.1) 1 1.1
knowhowmuchmykneeismoving (38.5) (29.2) (1.1)
5.Whenperformingactivitiesofdailyliving(housework,work,etc.),Idonot 22 16 14(21.5) 10 2(3.1) 1 1.2
knowwhatkindofpositionmykneeisin (35.4) (24.6) (15.4) (1.1)
6.Icannotimagemyknee’scontourcorrectly 18 19 11(16.9) 17 0(0.0) 1 1.4
(27.7) (29.2) (26.2) (1.1)
7.Ifeellikemykneeisbigger(swollen) 19 12 19(29.2) 7(10.8) 8(12.3) 2 1.5
(29.2) (18.5) (1.3)
8.Ifeellikemykneehasshrunk 31 18 10(15.4) 5(7.7) 1(1.5) 1 0.8
(47.7) (27.7) (1.0)
9.Mykneefeelsdifferenceswithrightandleft.(Onesidefeelsdullorfat) 10 6(9.2) 16(24.6) 21 12 3 2.2
(15.4) (32.3) (18.5) (1.2)
Total 12 12.4
(7.6)
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Fig1.Item-personthresholdmap.Personsoflesserdisturbedbodyperceptionanditemseasiertoendorsearelocated
ontheleftsideofthelogitscale(ie,<0logits);Personsofhigherdisturbedbodyperceptionanditemsofgreaterdifficultyto
endorsearelocatedtotherightofthelogitscale(ie,>0logits).Itemendorsabilitymeanissetat0logitsbydefault.
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Categoryorder. Theaverageagreeabilitymeasuresoftherespondentsadvancedas
expectedacrosstheratingscalecategoriesandtherewasneitherexcessivepositivenornegative
fitstatistics,suggestingthecategorystructureisadequate(Table4).Eachcategoryhasadis-
tinctpeaksuggestingthecategoriesarenotdisordered—thatis,thestepcalibrations(the
thresholdsbetweencategories)areorderedasexpected(Fig3).
Unidimensionality. Table3summarizesthefitstatisticsforthenineitems.Twoitems
(Item7and9)demonstratedexcessivepositiveinfitandoutfitstatisticsandoneitem(Item4)
demonstratedslightlyexcessivenegativeinfitandoutfitstatistics.Criticallyhowever,these
resultsdonotposeathreattovalidity.PCAofresidualsindicatedthattheunexplained
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Table3. Averageitemendorsabilitythresholds,includingfitstatistics.
Item Measure(Logits) SE Infit Outfit
(mnsq) (mnsq)
9 -1.21 0.14 1.46 1.41
2 -0.49 0.14 0.88 0.85
7 -0.29 0.14 1.74 1.61
6 -0.07 0.14 0.66 0.67
5 0.14 0.15 0.82 0.81
1 0.32 0.15 1.16 1.38
4 0.32 0.15 0.56 0.53
3 0.56 0.16 0.72 0.71
8 0.73 0.16 1.09 0.87
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varianceofthefirstcontrastwas1.9eigenvalueunits,indicatingunidimensionality.Assess-
mentoflocaldependenceidentifiednostrongcorrelationsbetweenallitems.Thissuggested
thattheresponsestoallitemswereindependent.
Personfit. Analysisofpersonfitidentified13participants(20.0%)withexcessivepositive
outfit(>1.5logits).Nosignificantassociationswerefoundbetweenbetweenthosewhofitver-
susthosewhodidnotfittheRaschmodel:age(p=0.13)gender(p=0.15),painintensityat
Fig2.DifferentialtestfunctioningbetweentheFreBAQ-JandFreKAQ-J.Thedashedlineshowsatrend-linethroughthemeanofbothsetsof
items,andtheblacklinesshowtheupperandlower95%confidencebands.
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Table4. Averagecategoryscorethresholds,includingfitstatistics.
Categoryscore Measure Infit Outfit
(Logits)
0 -1.86 1.11 1.13
1 -1.10 0.82 0.83
2 -0.33 0.79 0.76
3 0.39 1.02 0.95
4 1.15 1.32 1.28
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rest(p=0.60),painduringmotion(p=0.90),painduration(p=0.15),disability(p=0.34),
andtheFreKAQ-Jscore(p=0.80).
Internalconsistency. Thepersonreliabilitywas0.81andtheCronbach’salphawas0.88
suggestingtheFreKAQ-Jhasgoodinternalconsistencyandissuitableforbothindividualand
groupuse.
Differentialitemfunctioning(DIF). Differentialitemfunctioning,characterizedasasig-
nificantdifferenceofgreaterthan0.5logits,wasnotobservedbetweenage,gender,paininten-
sity,paindurationordisabilitysubgroupssuggestingtheitemswerenotbiased.
Fig3.Probabilitycurvesforthe5-categoryJapaneseversionoftheFremantleKneeAwarenessQuestionnaire.C0,
never;C1,rarely;C2,occasionally;C3,sometimes;C4,always).
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Test-retestreliability
Oftheparticipantswhoreportednochange(thedifferencebetweenfirstandsecondroundof
painintensityduringmovementisunder10mm)inpainintensityduringthepast2weeks
(n=23),therewasexcellentagreementbetweentestandretesttotalscores,withanICC of
3,1
0.76[95%confidenceinterval(CI)0.52–0.89].
Relationshiptoclinicalstatus
Therewasnosignificantdifferenceinage(p=0.21),gender(p=1.0),height(p=0.36)or
weight(p=0.14)betweenthekneeOAgroupandthecontrolgroup.ThekneeOAgroup
scoredsignificantlyhigherontheFreKAQ-Jthanthecontrolgroup(p<0.001,meandiffer-
ence=9.0,95%CI=6.7to11.1).TheFreKAQ-Jwassignificantlycorrelatedwith,painduring
motion(rho=0.37),OKS(rho=-0.41),PCS(rho=0.70)andTSK(rho=0.49)andanxiety
(rho=0.46;p<0.007forall),butnotdurationofpainintensity(rho=-0.06;p=0.76),painat
rest(rho=0.27;p=0.02),anddepression(rho=0.32;p=0.01)(Table5).
Discussion
Weaimedtodevelopaknee-specificJapaneseversionoftheFreBAQ,assessitspsychometric
properties,determinewhetherpeoplewithkneeOAhaveself-reportedperceptualimpairment
andinvestigatetherelationshipbetweenimpairedself-perceptionandclinicalstatus.Our
resultssuggestthatthenewlydevelopedFreKAQ-Jhasacceptableconstructvalidity,internal
consistency,andtest-retestreliability.Thatthenineitemsformaunidimensionalscalesug-
geststhescorecanbesummedtoprovideameasureofperceptualimpairment.Thescaleis
notbiasedbyothercharacteristics,suchasageorgender,andthecategoryratingscalefunc-
tionsasexpected.OnlytwopeoplewithkneeOA(3.0%)scoredzeroandnonehadafullscore,
suggestingthattheFreKAQ-Jhasneitherfloornorceilingeffects,althoughthosewithvery
minorperceptualdisturbancesarelesswellcapturedbytheFreKAQ-Jthantherest.Partici-
pantswithkneeOAscoredhigherthanhealthycontrol.Overall,theFreKAQ-Jshowedade-
quatepsychometricpropertiesforuseinevaluatingimpairedbodyperceptionofpeoplewith
kneeOAintheJapanesepopulation.
ThedifferentialtestfunctioningresultsbetweentheFreKAQ-JandtheFreBAQ-Jdemon-
stratedthatitemsatthetopandbottomofthescalewerestablewithsomedisorderinginthe
middleitems,suggestingtheconstructbetweentheFreKAQ-JandtheFreBAQ-Jissimilar.
TheFreBAQhasatheoreticalconstructofperceptualimpairment[27],therefore,theFre-
KAQ-Jisalsolikelyavalidassessmentofperceptualimpairment.
Table5. CorrelationsbetweentheFreKAQ-Jtotalscoreandclinicalsymptom.
Correlationcoefficient(R) pvalue
Durationofpainintensity -0.06 0.76
Painintensity
Rest 0.27 0.02
Motion 0.37 0.002
Disability
OKS -0.41 0.001
Catastrophization(PCS) 0.70 <0.001
Kinesiophobia(TSK) 0.49 <0.001
Anxiety 0.46 <0.001
Depression 0.32 0.01
https://doi.org/10.1371/journal.pone.0179225.t005
PLOSONE|https://doi.org/10.1371/journal.pone.0179225 June26,2017 10/15