Measurement properties of the Musculoskeletal Health ... · symptoms, functional ability and...

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Preprint:Pleasenotethatthisarticlehasnotcompletedpeerreview.

MeasurementpropertiesoftheMusculoskeletalHealthQuestionnaire(MSK-HQ):abetweencountrycomparisonCURRENTSTATUS:UNDERREVIEW

DavidHøyrupChristiansen

david.christiansen@vest.rm.dkCorrespondingAuthorORCiD:https://orcid.org/0000-0001-7458-3921

GarethMcCrayInstititeforPrimaryCareandHealthSciences,KeeleUniversity

TrineNøhrWindingDeparmentofOccupationalMedicine,DanishRamazziniCentre,UniversityClinic,Herning

JohanHviidAndersenDeparmentofOccupationalMedicine,DanishRamazziniCentre,UniversityClinic,Herning

KentJacobNielsenDeparmentofOccupationalMedicine,DanishRamazziniCentre,UniversityClinic,Herning

SvenKarstensDeparmentofComputerScience;TherapeuticSciences,TrierUniversity

JonathanCHillInstituteforPrimaryCareandHealthSciences,KeeleUniversity

DOI:10.21203/rs.2.19546/v2

SUBJECTAREASHealthEconomics&OutcomesResearch

KEYWORDSpatientreportedoutcomes,usability,psychometrics,responsiveness,interpretability

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AbstractBackground:TheMusculoskeletalHealthQuestionnaire(MSK-HQ)hasbeendevelopedtomeasure

musculoskeletalhealthstatusacrossmusculoskeletalconditionsandsettings.However,theMSK-HQ

needstobefurtherevaluatedacrosssettingsanddifferentlanguages.

Objective:Theobjectiveofthestudywastoevaluateandcomparemeasurementpropertiesofthe

MSK-HQacrossDanish(DK)andEnglish(UK)cohortsofpatientsfromprimarycarephysiotherapy

serviceswithmusculoskeletalpain.

Methods:MSK-HQwastranslatedintoDanishaccordingtointernationalguidelines.Measurement

invariancewasassessedbydifferentialitemfunctioning(DIF)analyses.Test-retestreliability,

measurementerror,responsivenessandminimalclinicallyimportantchange(MCIC)wereevaluated

andcomparedbetweenDK(n=153)andUK(n=166)cohorts.

Results:TheDanishversiondemonstratedacceptablefaceandconstructvalidity.Outofthe14MSK-

HQitems,threeitemsshowedDIFforlanguage(pain/stiffnessatnight,understandingconditionand

confidenceinmanagingsymptoms)andthreeitemsshowedDIFforpainlocation(walking,

washing/dressingandphysicalactivitylevels).IntraclassCorrelationCoefficientsfortest-retestwere

0.86(95%CI0.81to0.91)forDKcohortand0.77(95%CI0.49to0.90)fortheUKcohort.The

systematicmeasurementerrorwas1.6and3.9pointsfortheDKandUKcohortsrespectively,with

randommeasurementerrorbeing8.6and9.9points.Receiveroperatingcharacteristic(ROC)curves

ofthechangescoresagainstpatients’ownjudgmentat3monthsexceeded0.70inbothcohorts.

AbsoluteandrelativeMCICestimateswere8-10pointsand26%fortheDKcohortand6-8pointsand

29%fortheUKcohort.

Conclusions:ThemeasurementpropertiesofMSK-HQwereacceptableacrosscountries,butseem

moresuitedforgroupthanindividuallevelevaluation.Researchersandcliniciansshouldbeaware

thatsomediscrepancyexitsandshouldtaketheobservedmeasurementerrorintoaccountwhen

evaluatingchangeinscoresovertime.

BackgroundPaininmusclesandjointsisoneoftheWesternWorld’schiefpublichealthconcernsandaleading

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causeofreducedfunctionalandworkingcapacity[1].Inordertodevelopeffectivetreatments,andto

evaluatetheireffects,reliableandvalidmeasurementtoolsareessential.Thehealth-related

consequencesofmusculoskeletaldisorders,suchasbackandkneepain,canrarelybeidentifiedor

measuredusingdiagnosticimagingorotherobjectivemeasurementmethods[2-5].Therefore,patient

reportedoutcomesmeasures(PROMs)areincreasinglyusedtosupporttheassessment,treatment

andmonitoringofpersonswithmusculoskeletaldisorders[6].PROMsrevealaperson’sperceived

symptoms,functionalabilityandqualityoflife,andaretypicallyadministeredviaquestionnaire.A

widerangeofquestionnairesformusculoskeletaldisordershavebeendeveloped.However,these

questionnairesaretypicallylimitedtospecificpartsofthebody,e.g.painintheshoulderandarm[7],

neckandback[8,9],hipandknee[10].Although,region-specificquestionnairesinspecificpatient

populationandclinicaltrialsservesitspurposewell,theycanoftenbedifficulttoadministratefor

healthcareprofessionals(e.g.generalpractitionersandphysiotherapists)inprimarycare,whosee

patientswithdiversemusculoskeletaldisorders,oftenpresentingwithconcurrentpainfromseveral

locations[11].Although,moregeneralmusculoskeletalquestionnairesexist[12,13],theseare

relativelycomprehensiveinlengthandthereforelesssuitedtoevaluatechangesovertime,because

oftheburdenofadministrationandpatientcompletionatmultipletimepoints.Inaddition,someonly

coverasmallnumberofhealth-relateddomains(e.g.painandfunction)[13],andtherebymaynotbe

sensitivetothemultidimensionalityoftreatmenttargetsinherentinmanagingmusculoskeletal

disorders.

Asaconsequence,VersusArthritis(https://www.versusarthritis.org)fundedcollaborationbetweenthe

universitiesofOxfordandKeeletodeveloptheMusculoskeletalHealthQuestionnaire(MSK-HQ)in

2012[14].TheMSK-HQaimstocapturepatientandclinicianprioritisedkeyoutcomesacrossarange

ofmusculoskeletalconditions.Theinstrumentconsistsof14itemsandcoversanumberofhealth-

relateddomains,includingsymptoms,physicalfunctioning,dailyactivitiesandwork,physicalwell-

being,confidencetomanagesymptoms,conditionunderstandingandsocialactivities.Eachitemon

theMSK-HQisansweredona5-pointverbalratingscale(responsescodedfrom‘notatall’=4to

‘extremely’=0,exceptforitems12‘understandingcondition’and13‘confidenceinmanaging

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symptoms’,whichhavetheresponseoptionsinthereverseorder).Scoresaresummed,rangingfrom

0to56,where56isthebestpossiblestateofmusculoskeletalhealth.Therelativelybriefformat

makestheMSK-HQmoresuitabletomonitorandcomparemusculoskeletalhealthstatusacross

variousconditionsandthroughouttheclinicalpathway.TheoriginalversionoftheMSK-HQhas

demonstratedhighcompletionrates,goodtest-retestreliabilityandstrongconvergentvaliditywith

referencestandardsinfourdifferentMSKcohorts[14].However,aquestionnaire’susabilityand

measurementpropertiescannotnecessarilybetransferredtoothercountries,languagesand

healthcaresystems[15-17].Therefore,carefultranslation,cross-culturaladaptation,testingand

validationarenecessaryinordertotakeaccountanyculturalandcomprehensibility-related

differencesbetweenthecountries.Although,cross-culturaladaptationandwithincountryevaluation

oftenareperformedwithPROMs,assessmentofmeasurementinvariancewithrespecttolanguage

andpatientscharacteristics,aswellasdirectcomparisonofmeasurementpropertiesacrosscountries

arelessfrequent.Theobjectivesofthepresentstudywereto1)translateandcross-culturaladapt

theMSK-HQforuseinaDanish-speakingpopulation,and2)evaluateandcomparemeasurement

propertiesoftheMSK-HQacrossDanish(DK)andEnglish(UK)cohortsofpatientsconsultingprimary

carephysiotherapyserviceswithmusculoskeletalpain.

MethodsTranslationandcross-culturaladaptation

WetranslatedtheMSK-HQintoDanishinaccordancewithinternationalstandards[18].Thiswas

doneinclosecollaborationwiththelicenseholderoftheMSK-HQquestionnaire,OxfordUniversity

InnovationLtd(http://innovation.ox.ac.uk)andarepresentativeoftheresearchgroup,whodeveloped

thequestionnaire(JCH).AprofessionalEnglishlanguagetranslatorspecialisinginmedicaltranslation

andabilingualphysiotherapist,bothDanishnativespeakers,translatedthequestionnairefrom

EnglishintoDanish.Subsequently,theirtranslationswerecomparedataconsensusmeetinginthe

projectgroupwithparticipationofbothtranslators.AprofessionalnativeEnglish-speakingtranslator

back-translatedthequestionnairefromDanishintoEnglish,withoutanypriorknowledgeofthe

originalversion.Theback-translationwascomparedtotheoriginalversion.Afterwards,the

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translationreportwasreviewedbyJCHandapproved.Finally,weperformedcognitivedebriefing

interviewswith13patientswithmusculoskeletaldisordersrecruitedinonephysiotherapyclinicinthe

CentralDenmarkRegion.Theresultsofthecognitivedebriefingwerepresentedandreviewedinthe

projectgroupandthefinalversionofthequestionnairewascompleted.

Designandstudypopulations

Thestudywasaprospectivecomparativestudyencompassingtwoconsecutivelyrecruitedcohortsof

patientswithmusculoskeletaldisordersinprimaryphysiotherapypracticeinDKandUK.

DKcohort

Participants

Consecutiveadult(≥18years)consultersreferredtophysiotherapywithamusculoskeletaldisorder

wereinvitedtoparticipateinsixphysiotherapy(PT)clinicsintheCentralDenmarkRegion.

ParticipantshadtobeabletounderstandandspeakDanishwellenoughtocompletequestionnaires,

withnofurtherinclusioncriteriaapplied.IntheperiodJanuary-July2017atotalof180patients

agreedtoparticipate,ofwhom27wereexcludeddueto‘noshow’/cancelations(n=9),withdrawal

(n=5),otherdiagnosisthanmusculoskeletal(n=2),otherreasons(n=4)ordidnotcompletebaseline

questionnaire(n=7),leaving153patientsforanalysis.

Datacollection

Atfirstcontact,thepatientwasinformedabouttheproject.Ifthepatientagreedtoparticipate,ane-

mailwithalinktoanelectronicquestionnairewassenttothepatient(baseline).Thequestionnaire

includedtheDanishversionsoftheMSK-HQ,thegenericEQ-5D-5L[19-21]andvalidatedreference

standardmeasuresdependingonthepainregionfromwhichthepatient’smainproblemoriginated;

ShortenedDisabilitiesoftheArm,ShoulderandHand(Q-DASH)[22,23],NeckandBackdisability

Indexes(ODIandNDI)[24-26],Pain,stiffnessandfunctionmodulesofKneeinjuryandHipDisability

OsteoarthritisOutcomeScores(KOOSandHOOS)[27-29].AnappointmentwasmadeforafirstPT

consultation(test-retest)5-7dayslater.Immediatelybeforethisappointment,thepatientoncemore

completedthequestionnaire.Follow-upquestionnairesweresentaftersixand12weeksbye-mail.In

addition,inretestandfollow-upquestionnaires,patientswereaskedtoratetheoverallchangein

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theirconditionona7-pointscale(muchbetter,better,slightlybetter,unchanged,slightlyworse,

worse,muchworse).Atotalof134patients(88%)completedthetest-retestquestionnaire(median

timeinterval6days[Interquartilerange3-8days]).Follow-upquestionnaireswerecompletedby118

patients(77%)atsixweeksand128patients(84%)at12weeks.ForcomparisonwiththeUKcohort

onlytheresultsofthe12-weekfollow-upareincludedinthepresentstudy.

UKcohort

Participants

TheUKcohortwasdrawnfromtheprimarycarephysiotherapysampleusedastheoriginalvalidation

cohortfortheMSK-HQ.Thedetailsofmaterialsandmethodshavepreviouslybeendescribed

elsewhere[14].Briefly,thecohortincluded210consecutiveconsultersincommunitymusculoskeletal

physiotherapyclinicsinfiveUKWest-Midlandstowns.Ofthose166(78%)withtest-retestdatawere

availableforthepresentstudy.

Datacollection

ParticipantscompletedtheEnglishpaperversionoftheMSK-HQandtheEQ-5D-5Lindexbeforethe

startoftreatmentatthefirstclinicvisit(baseline)andagainatthesecondvisit,typically2weeks

later(test–retest).Follow-upquestionnaireswerecompletedat12weeksby133(80%)patients.A

transitionquestiononoverallchangeintheconditionona5-pointscale(muchbetter,slightlybetter,

unchanged,slightlyworse,muchworse)wascompletedbypatientsattest-retestand12-weekfollow-

up.

Statisticalanalysis

Descriptivestatistics

Descriptivestatisticswerecalculatedforallvariablesandcomparedbetweenthetwocohorts.Sum

scoreswerecalculatedatalltimepointsandrawscoreswerecalculatedifnomorethan

3itemsweremissingintherespectivescore;otherwise,thescorewasleftmissing.Possiblefloorand

ceilingeffectswereexaminedandsucheffectswereconsideredtobepresentifmorethan15%ofthe

respondentsachievedthehighestorthelowestsumscore,respectively.

Constructvalidity

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AsnoreferencestandardmeasureswerecollectedfortheUKprimarycarecohort[14],weonly

assessedconstructconvergentvalidityfortheDanishversionoftheMSK-HQ.Thiswasdoneby

correlationanalysesbetweentheMSK-HQscoresandtherelevantreferencestandardmeasures

scoresatbaseline(Q-DASH,ODI,NDIandWOMACscorescalculatedfromKOOSandHOOS).Likewise

longitudinalconvergentvaliditywasassessedbycorrelationanalysesbetweenMSK-HQandreference

standardmeasureschangescoresatthreemonths.Basedonfindingsfromtheoriginalvalidation

studyoftheMSK-HQ[14]andpreviousliteratureofhealthoutcomeresearch[30-32],weexpected

correlationsbetweenMSK-HQandrelevantreferencestandardmeasurestobeatmoderatetostrong

(r=≥0.5).

Cross-culturalvalidityandmeasurementinvariance

Measurementinvarianceaccordingtolanguage,categoriesofage,painsite,durationofpain,and

workstatus,wasassessedbyDifferentialitemfunctioning(DIF)analysisofbaselineratingsofthetwo

cohorts.DIFistheassessmentoftheextenttowhichitemsfunctiondifferentlybetweenvarious

groups,whenthescoresamongthosegroupsarecorrectedfor.UniformdichotomousDIFontheraw

scoreswasassessedinthispaperviatheMantel-Haenszel(MH)statisticcalculatedintheR3.4.1[33]

packagedifR[34].Itempurificationwasusedandadjustmentformultiplecomparisonswasmadevia

Holm’smethod.TheassessmentoftheeffectsizefortheDIFwasmadeontheETSDeltascaleforthe

dichotomouscategories(i.e.,country,duration,workstatus)[35].NotethatMSK-HQitemswere

dichotomisedsuchthatthetwolowerimpactcategories(‘notatall’and‘slightly/rarely’)opposedthe

threehigherimpactcategories.Furthermore,fortheassessmentofpainlocation,‘neck’was

collapsedwith‘back’asthereweretoofewinstancesofneckpaintocalculatetheMHstatistic

robustly.

Measurementerrorandreliability

Astest-retestwasadministereddifferentlyinthetwocohortswithrespecttotimeintervaland

initiationoftreatment,werestrictedtheanalysistopatientswhoreportedtheirconditiontobe

‘stable’betweenadministrations.SystematicmeasurementerrorbetweenMSK-HQscoresatbaseline

andretestwasanalysedbyBland-Altmanplotandpairedt-testfortheDKandUKcohorts.Further

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randomerrorswereestimatedbystandarderrorofmeasurement(SEM)andminimaldetectable

change(MDC=1.96×√2×SEM)wascalculated.Cronbach’salphawascalculatedtoassessinternal

consistency.Theintraclasscorrelationcoefficient(ICC2.1)wasusedtoassesstest-retestreliability,

andforsingleitemsCohen’sKappawithquadraticweightswasused.Confidenceintervals(95%CI)

forKappavalueswereobtainedusingnon-parametricbootstrapmethods(1000replications).

Sensitivitytochange,responsivenessandinterpretability

ToevaluatesensitivitytochangeMSK-HQchangescoresfrombaselinetothreemonthsandeffect-

sizestatistics(i.e.,meanchange/standarddeviationatbaseline)werecalculatedandcompared

betweenthetwocohorts.ForresponsivenesstheMSK-HQ'sabilitytodiscriminatebetween

unchangedpatientswascalculatedandcomparedbetweencohortsbyreceiver-operating-

characteristic(ROC)curveanalyseswithlargeimprovement(muchbetter,betterversusalittle

better,unchanged,littleworse)andsmallimprovement(muchbetter,better,littlebetterversus

unchanged),usingthetransitionquestionasexternalanchor.Responsivenesstoworseningwasnot

analysed,asonlyfewpatientsratedtheirconditiontobe‘worse’or‘muchworse’.Minimalclinically

importantchange(MCIC)valueswereestimatedbythePythagoras'Theorem(a^2+b^2=c^2)to

choosethechangescoreclosesttotheupperleft-handcorner,whichbestdiscriminatedbetween

improvedandunchangedpatients[36].AsMCICvaluescanbeaffectedbybaselinescores,analysis

wasrepeatedwithrelativechangescores(i.e.,changescoresexpressedaspercentagesofthe

baselinescores)[37].Finally,asakeyvisonforthedevelopmentoftheMSK-HQwastoproducea

singlemusculoskeletalhealthmeasuresuperiortogenerichealthtools,wecomparedeffectsize

estimatesandareasundertheROCcurvefortheMSK-HQandtheEQ-5Dchangescores[38].The

statisticalpackageSTATAversion15wasused.

ResultsTranslationandcross-culturaladaptation

Inthetranslationprocessafewitemshadtobeslightlyrephrasedandtheresponsecategory

‘severely’waschangedto‘alot’tofittheDanishlanguage.Afewotherissueswereraisedduring

translation.Thetwodifferentconstructs;painandstiffnessusedinitem1anditem2ledtosome

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discussionintheprojectgroup,aswellasthedifferentconstructsinitem12‘understanding

condition’anditem13‘confidenceinmanaging’.However,cognitivedebriefinginterviewswithpilot

patients(fivemalesandeightfemales,32–59yearsofage)withvariousmusculoskeletaldisorders

revealednodifficultieswithrespecttotheabove-mentionedconcerns.Ingeneral,patientsfoundthe

DanishversionoftheMSK-HQeasytocomplete(2-6min)anditemswerewellunderstood,thusno

furtherchangeswereneeded.Patientsdidnotseemtodistinguishbetweenpainandstiffness,and

mostpatientsfoundtheitemsregardingunderstandingtheircondition(item12)andconfidencein

managing(item13)tobeimportant.TheDanishversionoftheMSK-HQisavailableonlicence

request:https://process.innovation.ox.ac.uk/clinical.

Descriptivestatistics

Thepatientcharacteristicsofbothcohortsarepresentedintable1.Thetwocohortswerefairly

similarwithrespecttodistributionofpainsites.ThepatientsintheDKcohortwereslightlyyounger,

includedmorewomen,andhadahigherpercentageofpatientswhowereworking.Nofloororceiling

effectswereobservedatanytimepoint.IntheDanishcohortmissingdatawasreplacedbymean

itemscoresfortwopatientswholefttwoitemsunansweredandtwopatientswholeftthreeitems

unansweredatbaseline,andtwopatientswholeftoneitematretestandfollow-up.FortheUKcohort

meanitemscorewascalculatedfortwopatientsleavingoneitemunanswered.

Constructvalidity

Thecorrelationcoefficients(SpearmanRho)betweentheDanishMSK-HQandrelevantreference

standardmeasureswere0.63(CI,0.38to0.79)fortheQ-DASH,0.71(CI,0.53to0.88)fortheODI,

0.60(CI,0.25to0.81)fortheNDI,andfortheWOMAC0.84(CI,0.73to0.91).Correspondingvalues

forchangescoreswere0.65(CI,0.38to0.82)fortheQ-DASH,0.74(CI,0.54to0.86)fortheODI,0.52

(CI,0.05to0.80)fortheNDI,andfortheWOMAC0.70(CI,0.50to0.83).

Crossculturalvalidityandmeasurementinvariance

Withregardstocountrydifferences,threeitemsshowedstatisticallysignificantlevelsofDIF,allwith

largeeffectsizesaccordingtotheETSDeltascale[35],thesewereitems2(pain/stiffnessatnight;

lowerthanexpectedinUK–MH=8.54,p=0.04),12(understandingcondition;lowerthanexpected

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inDK-MH=11.37,p=0.01),and13(confidenceinmanaging;lowerthanexpectedinDK-MH=

15.21,p=0.001).Withregardstopainlocation,threeitemsshowedstatisticallysignificantlevelsof

DIF,items3,4and5.Item3(walking;hardestforlowerextremities,moderateforback/neckand

easiestforupperextremities-MH=38.71,adj.p<0.001),item4(washing/dressing;harderforupper

extremities,easierforlowerextremitiesandback/neck-MH=11.34,adj.p=0.04),item5(physical

activitylevels;easierforupperextremities,harderforlowerextremitiesandback/neck-MH=14.57,

adj.p=0.01).Withregardstoagegroup,paindurationandworkingstatus,noitemsexhibited

statisticallysignificantDIF.

Measurementerrorandreliability

Of134patientsintheDKcohortand165patientsintheUKcohortwithretestMSK-HQdataavailable,

98and82patientsreportedtheirconditiontobe‘stable’betweenbaselineandretest,respectively

andwerethususedtocalculatethereliabilitystatisticspresentedintable2.Whencomparedtothe

UKcohort,smallersystematicandrandomerrorswereobservedintheDanishcohortandICCvalues

wereslightlyhigher.Internalconsistencywashighforbothcohorts.Themedian(range)weighted

kappawithsquaredweightsacrossthe14itemsfortheDKcohortwas0.69(0.54to0.84)as

comparedto0.67(0.31to0.80)intheUKcohort.Detailsofthetest-retestreliabilityofsingleitemsof

theMSK-HQareavailableinAppendixA.

Sensitivitytochange,responsivenessandinterpretability

At12weeksfortheDKcohortmeanchangescoreswere9.1(95%CI,7.7to10.6);ES1.1(CI0.9to

1.2)fortheMSK-HQandmeanEQ-5D-5Lindexscoreswere0.08(CI,0.06to0.10);ES0.7(CI,0.5to

0.8).ThecorrespondingvaluesfortheUKcohortweremeanscore8.9(CI,7.4to10.5);ES0.9(CI,0.8

to1.1)fortheMSK-HQandfortheEQ-5D-5Lindexmeanscore0.11(CI,0.07to0.14);ES0.5(CI0.3

to0.6).Thecorrelations(SpearmanRho)betweenthetransitionquestionofchangeinmaincomplaint

andMSK-HQchangescoreswere-0.66(CI,-0.75to-0.55)and-0.54(CI,-0.65to-0.40)fortheDKand

UKcohorts,respectively.Table3presentstheROCanalysesandMCICestimatesaccordingtothetwo

cutpointsofpatientperceivedimportantchangeinmaincomplaint.Although,ROCAUCdiffered

betweentheDKandUKcohorts,thesedifferencesdidnotreachstatisticalsignificance.TheMCIC

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estimateforabsolutechangeat12weekswaslargerfortheDKcohort,whereasforthepercentages

ofchangetheoppositewastrue.ThepercentagesreachingtheMCICthresholdfor‘large

improvement’were48%intheDKcohortand47%intheUK-cohort,whereasthecorresponding

valuesfor‘smallimprovements’were57%and56%,respectively.Figure1illustratestheROC

curvesrepresentingchangescoresfortheMSK-HQascomparedtoEQ-5D-5Lindexat12weeks.For

bothcohortstheMSK-HQproducedhigherROCAUCsthantheEQ-5D-5L.FortheDKcohortthe

differencebetweenMSK-HQandEQ-5D-5LROCareasindexreachedborderlinestatisticalsignificance

forbothlargeimprovement(p=0.05)andsmallimprovement(p=0.06).

DiscussionThisisthefirststudytoevaluateandcomparemeasurementpropertiesofthenewMSK-HQtool

acrossdifferentinternationalcohortsofmusculoskeletalpatientsconsultingprimarycare

physiotherapyservices.TheMSK-HQwastranslatedandcross-culturaladaptedtoDanishspeaking

population.TheDanishversionoftheMSK-HQdemonstratedgoodfacevalidityandconstructvalidity

wasconfirmedbymoderatetostrongcorrelationswithrelevantreferencestandardmeasures.Inthe

DIFanalysisthreeitemsdisplayedmeasurementinvarianceforlanguage(pain/stiffnessatnight,

understandingcondition,confidenceinmanaging)andthreeforpainlocation(walking,

washing/dressing,physicalactivitylevels),whereasnodifferenceswereobservedforage,pain

durationandworkingstatus.ForbothcohortstheMSK-HQdemonstratedgoodinternalconsistency,

acceptablelevelsofreliabilityandresponsivenesswithreliabilitycoefficientsandROCestimates

exceeding0.70[15].

Thestudybenefittedfromprospectivelycollecteddataintwocomparablephysiotherapycohortswith

highcompletionratesonquestionnaires.Thestudyhadsomelimitations.Noformalsamplesize

calculationforthepresentstudywasperformed,butasbothcohortsexceededtheCOSMIN

recommendationsofatleast100individualsforquantitativePROMstudies[15],webelievethe

samplesizesofthetwocohortstobeadequate.Itshouldalsobenotedthatdataofthetwocohorts

wascollectedandadministrateddifferently.Thus,onlylimitedpopulationdescriptorsacrossthetwo

cohortswereavailable,withdatabeinglesscompleteinthecomparativeUKcohortforthevariables

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painsiteanddurationofsymptoms.ThequestionnairesintheUKcohortwerepaperbasedwhereas

questionnairesintheDKcohortwerecompletedonline.AsstudiescomparingpaperVs,online

administeredpatient-reportedoutcomemeasuresindicatethesetwoassessmentmethodsarehighly

comparable[39],itisunlikelytohaveaffectedourresults.

Thehighcompletionrate,acceptablefaceandconstructvalidityobservedconfirmedearlierpromising

findingsfromtheinitialvalidationstudy[14].IntermsofreliabilityandmeasurementserrortheDK

versionseemstoperformslightlybetterthantheUKversioninourstudy.Wealsoobserveda

significantlylargersystematicmeasurementerroroftest-retestscoresofMSK-HQfortheUKcohort.

Thesefindingsmay,inpart,beexplainedbydifferencesinstudydesigns.TheDKcohortpatients

completedtest-retestquestionnaireswitha6daysintervalbeforeanytreatmentwasinitiated,

whereaspatientsintheUKcohortcompleteditwithina2weeksinterval.Although,thesedifferences

werelevelledoutbyrestrictingtest-retestanalysisto‘stable’patientsonly,itispossiblethatthe

longertimeintervalcouldhaveresultedinmoreimprovementamong‘stable’patientsintheUK-

cohort.Itcouldbearguedthatrestrictinganalysisto‘stable’patientswouldinevitablyproducelower

MDCestimates,thanif'unstable'patientswereincluded.Howeverinourcase,ifallavailablepatients

hadbeenincludeditwouldonlyhaveincreasedtheMDCestimatebyapproximatelyonepoint(results

notshown),andthereforenothavechangedtheoverallconclusionofthestudy.Anotherlimitationof

thepresentstudywasthatclassificationofimprovedorunchangedpatientswerebasedonasingle

transitionscalequestionasexternalanchor(i.e.improvementinoverallcondition),whichmight

measurevaryingaspectsoftheoutcome[32].Theuseofseveralanchorscoveringdifferentaspects

oftheoutcome(e.g.pain,functionandpatientsatisfaction)mighthaveproducedotherresults.

Furthermore,notethatalternativemethodstoderiveMCICestimatesdoexist[40,41]howeverwe

chosetousetheROCcurvemethodtopreservecomparabilitywithotherstudiesinthefieldand

communicabilitywithreadersunfamiliarwithalternativemethods.

ThreeMSK-HQitemsexhibitedDIFacrosscountries.Item2‘pain/stiffness’atnightwasscoredlower

(i.e.morepain/stiffness)inUKpatientsalthoughnodifferenceswerefoundforthesimilaritem1

‘pain/stiffness’duringtheday.DKpatientshadloweritemscoreswithregardstounderstanding

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conditionandconfidenceinmanaging(item12and13).Thesedifferencesmayeitherimply

translationalproblems,culturaldifferencesortruedifferencesbetweencohorts.Thisshouldbe

furtherinvestigatedthroughqualitativeinquiriestoexplorehowpatientsunderstandandinterpret

thesequestionsacrosscountries.Although,thesetwoitemsweredeemedimportantandrelevantby

patients,theyhavepreviouslyshowntocorrelatepoorlywiththetotalMSK-HQscore[14].Hence,it

couldbediscussedwhethertoincludetheseitemsintheoverallsumscoreortousethesequestions

separatelytofacilitatepatientcommunicationandsharedclinicaldecisionmaking.Thefindingsthat

noMSK-HQitemsdifferedforage,paindurationandworkingstatusaddstotheperviousresultsfrom

thevalidationstudyontheoriginalversion[14].Withregardstopainlocation,thelowerscoresfound

initem3‘walking’forextremitiesandback/neckpatients,whencomparedtoupperextremity

patientswasnotanunexpectedfinding,andseemsinlinewiththeoppositepatternforitem4

‘washing/dressing’.Itcouldbespeculatedthatthehigherscoresfoundforupperextremitiespatients

foritem5‘physicalactivitylevels’,maybeduetoexamplesgiven(goingforawalkorjogging),as

thesedonotincludedphysicalactivitiesrelatedtoupperextremities.Addingridingyourbikeor

playingtennis/golfcouldbeapotentialsolutiontothisdiscrepancybetweenpainsites.

Thedistinctionbetweenformative(i.e.,theitemscausetheconstruct)andreflective(i.e.,the

constructcausesthatwhichismeasuredbytheitems)toolsisnotalwayseasytomakeandtoolscan

exhibitaspectsofbothconceptualframeworks[42].Notethatpreviously,theMSK-HQhadbeen

consideredtobeaformativetoolhoweveronfurtherreflectionwefeelthattoolismuchbetter

characterisedasbeingreflective.ThemeasurementpropertyestimatesobservedfortheMSK-HQin

thepresentstudydidnotdifferfrommostexistingregion-specificPROMs[7,9,10,43]andgeneral

musculoskeletalPROMs[44].ForPROMs,reliabilitycoefficients≥0.7areconsideredadequatefor

groupcomparisons,whereas≥0.9areneededtomonitorindividualpatients[45].Similartomost

musculoskeletalPROMs,theMSK-HQonlyexceedthefirstmentionedthreshold,andtherefore,at

present,maybemostsuitableforgroupevaluation.MDCvaluesformusculoskeletalPROMsare

commonlyreportedtorangefrom10to20%ofthescale,whichisinlinewithourfindingsforthe

MSK-HQ.Toensurethatachangescoreonanindividualpatientlevelisclinicallyrelevant,theMCIC

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shouldbegreaterthan,oratleastequalto,therandommeasurementerror(MDC)ofaninstrument.

ThiswasonlytrueintheDanishcohortofthepresentstudyandforthecut-off-leveloflarge

improvements,makingtheinterpretabilityofsmallchangesofindividualscoresoftheMSK-HQmore

challenging.AsMCICestimatesbasedonrelativescoreswereunaffectedbythecut-offlevelofthe

transitionquestionandrelativescoreshaveshowntobelesssensitivetobaselinescores[37];the

MCICpercentseemsthepreferablechoice.However,bothabsoluteandrelativeMCICvaluesvaried

betweenthetwocohorts.Thesedifferencesmaypartlyberootedintheuseofdifferentscalingof

transitionquestionofmaincomplaint(DKcohort7versus5responsecategories),whereastronger

correlationbetweenthetransitionquestionandMSK-HQchangescoresat12weekswasobserved.On

theotherhandtheproportionexceedingMCICthresholdsbetweentheDKcohortandUKcohortdid

notdiffersubstantially;largeimprovements(48%versus47%)andsmallimprovements(57%versus

55%).TheMSK-HQseemstodiscriminatewellbetweenunchangedandimprovedpatientsacrossthe

twocohorts.AkeyvisionoftheMSK-HQwastoproduceasinglebroadhealth-statusmeasuremore

sensitivetochangethangenerichealthtools.InbothcohortseffectsizesoftheMSK-HQwere

considerablylargerthanthoseoftheEQ-5D-5L,whichindicatessuperiorityoftheMSK-HQ.Whereas

fortheabilityofMSK-HQtodiscriminatebetweenimprovedandunchanged(i.e.responsiveness)a

patientat3months,superioritywasonlyobservedwithrespectintheDanishcohort.

ConclusionInthisstudyweperformedacross-countrycomparisonoftheMSK-HQquestionnaireamong

musculoskeletalpatientsconsultingprimarycarephysiotherapyservices.Although,somediscrepancy

forlanguageandpainsitelocationwasfoundforsingleitems,theMSK-HQgenerallyproduced

comparableresultsacrossthetwocohorts.TheDanishversionoftheMSK-HQappearstooutperform

theoriginalEnglishversionandhasshowntobeareliable,valid,sensitiveandresponsiveinstrument

tocaptureandmonitormusculoskeletalhealthstatus.

AbbreviationsMSK-HQ=TheMusculoskeletalHealthQuestionnaire

PROM=patientreportedoutcome

15

DIF=Differentialitemfunctioning

ICC=IntraclassCorrelationCoefficients

SEM=standarderrorofmeasurement

MDC=minimaldetectablechange

MCIC=Minimalclinicallyimportantchange

CI=Confidenceintervals

SD=standarddeviation

DeclarationsEthicsapprovalandconsenttoparticipate

TheDKcohortstudywasapprovedbyTheDanishDataProtectionAgency(Jno.1-16-02-542-16).

AccordingtoDanishlaw,approvalbytheethicscommitteeandwritteninformedconsentwasnot

required.Theeligiblepatientswereprovidedwithinformationaboutthestudyanditspurpose,

includingthatparticipationwasvoluntary.FortheUKcohortethicswasobtainedseparatelyfromthe

UKNHSHealthResearchAuthorityNationalResearchEthicsServiceCommittee(approvalreference:

15/YH/0167and15/WA/0040).

Consentforpublication

Notapplicable.

AvailabilityofDataandMaterials

DKcohortdatacannotbemadepubliclyavailableaccordingtoDanishregulations.Dataarehowever

availablefromtheauthorsuponreasonablerequestandpermissionoftheDanishDataProtection

Agency.FortheUKcohortadditionaldatacanbeaccessedonrequestviatheKeeledatarepository

at:http://www.keele.ac.uk/pchs/publications/datasharingresources/

CompetingInterests

Wedeclarenocompetinginterests

Funding

ThestudywassupportedbythePracticeResearchFoundationofDanishPhysiotherapistsand

ArthritisResearchUK(GrantRef.21405).

16

Authors’contribution

Allauthorsplannedanddesignedthestudy.DHCandGMperformedthestatisticalanalyses.DHC

draftedthemanuscript.Allauthorscontributedtointerpretationofdataandcriticalrevisionofthe

manuscript.Allauthorsreadandapprovedthefinalmanuscript.

Acknowledgments

Theauthorsthanktheclinicsthatparticipatedinthedatacollectionofthetwocohortstudiesand

patientsforparticipatinginthem.

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TablesTable1.Patientcharacteristics

VariablesDKcohort(n=153) UKcohort

(n=166)

Painsite

Back 45 (29.4) 47 (28.3)Neck 23 (15.0) 7 (4.2)Upperextremity 38 (24.8) 35 (21.1)Lowerextremity 47 (30.7) 57 (34.3)Other/unknown - - 20 (12.0)

Gender

Woman 97 (63.4) 92 (55.4)Men 56 (36.6) 74 (45.6)

Age

Yearsmean,(SD) 50.4 (13.8) 53.7 (15.7)

Workstatus

Working 96 (62.8) 94 (56.6)Notworking/Subsidedjob 6 (3.9)

7 (4.2)

Notworking/unemployed 14 (9.2)

5 (3.0)

Retired 26 (17.0) 52 (31.1)Onsickleave 11 (7.2) 7 (4.2)

Unknown - - 1 (0.1)

Durationofsymptoms

≤3months 62 (40.5) 77 (47.2)>3months 91 (59.4) 66 (39.8)Unknown - - 23 (13.9)

Baselinescore

MSK-HQ(0to56)mean,(SD) 32.3 (9.2)

30.5 (9.64)

EQ-5D-5Lindex(-0.6to1.0)mean,(SD) 0.69 (0.16)

0.55 (0.25)

Valuesarenumbers(percentages)unlessstatedotherwise.

Abbreviations:SD,standarddeviation

23

Table2.MeasurementerrorandreliabilityofMSK-HQscoresfortheDKcohortandtheUKcohort

DK-cohort

(n=98)UK-cohort

(n=82)Measurementerror

MeanDifference(95%CI) 1.6 (0.7to2.5) 3.9 (2.7to5.1)

SEM(95%CI) 3.1 (2.7to3.6) 3.6 (3.1to4.1)

MDC(95%CI) 8.6 (7.6to10.1) 9.9 (8.7to11.3)

Reliability

ICC(95%CI) 0.86 (0.81to0.91) 0.80 (0.50to0.90)

Cronbach’sα(Baseline) 0.88 (0.85to0.91) 0.89 (0.86to0.89)

Abbreviations:CI,Confidenceinterval;SEM,Standarderrorofthemeasurement;MDC,MinimalDetectableChange;

Table3.ROCandMCICestimatesaccordingtopatientperceivedimportantchangeinmaincomplaint

Cutpoints n(%) ROCAUC(95%CI) MCICROCSensitivity/

specificity%

Largeimprovement

DKcohort 64(52.5)0.83(0.75to

0.90) 10 78/81

UKcohort 49(37.1)0.79(0.71to

0.87) 8 78/69

Smallimprovement

DKcohort 87(74.3)0.85(0.77to

0.92) 8 76/80

UKcohort 85(64.9)0.76(0.68to

0.85) 6 71/71

a)Largeimprovement(muchbetter,betterversusalittlebetter,unchanged,littleworse)

b)Smallimprovements(muchbetter,better,littlebetterversusunchanged)

MCICROC:Estimatedastheoptimalcut-offpointoftheROCcurveusingabsolutechangescores.

MCICpercent:Estimatedastheoptimalcut-offpointoftheROCcurveusingrelativechangescores.

Abbreviations:ROC,receiveroperatingcharacteristic;AUC,areaunderthecurve;CI,confidenceinterval.Appendix

24

AppendixATest-retestreliabilityofsingleitemsoftheMSK-HQfortheDKandUKcohort

Item QuestionDKcohort(n=98)

UKcohort(n=82)

1 Pain/stiffnessduringtheday 0.73(0.63to0.81) 0.55(0.62to0.84)

2 Pain/stiffnessatnight 0.58(0.48to0.69) 0.68(0.55to0.78)

3 Walking 0.84(0.76to0.90) 0.74(0.62to0.84)

4 Washing/Dressing 0.64(0.44to0.80) 0.66(0.51to0.78)

5 Physicalactivitylevels 0.76(0.66to0.84) 0.69(0.56to0.79)

6 Work/dailyroutine 0.82(0.74to0.88) 0.61(0.48to0.71)

7 Socialactivitiesandhobbies 0.56(0.41to0.68) 0.59(0.43to0.73)

8 Needinghelp 0.78(0.66to0.87) 0.78(0.69to0.85)

9 Sleep 0.75(0.62to0.84) 0.80(0.71to0.87)

10 Fatigueorlowenergy 0.77(0.64to0.85) 0.75(0.63to0.83)

11 Emotionalwell-being 0.57(0.43to0.71) 0.78(0.69to0.85)

12 Understandingcondition 0.54(0.38to0.69) 0.31(0.13to0.48)

13 Confidenceinmanaging 0.58(0.45to0.70) 0.49(0.25to0.69)

14 Overallimpact 0.62(0.47to0.73) 0.58(0.43to0.69)

Valuesareweightedkappawithsquaredweights(95%Confidenceintervals)

Figures

25

Figure1

Receiver-operating-characteristic(ROC)curvesrepresentingabsolutechangescoresofthe

MSK-HQandEQ-5D-5LFootnoteValuesareROCareaestimates(95%confidenceintervals).