ContentslistsavailableatScienceDirect
Scandinavian Journal of Pain
j o u r n al ho me p ag e :w w w . S c a n d i n a v i a n J o u r n a l P a i n . c o m
Original experimental
Developing a model for measuring fear of pain in Norwegian samples:
The Fear of Pain Questionnaire Norway
Sara M. Vambheim
a,∗, Peter Solvoll Lyby
a,b, Per M. Aslaksen
a, Magne Arve Flaten
c, Ole Åsli
a, Espen Bjørkedal
a, Laila M. Martinussen
daDepartmentofPsychology,UiT,TheArcticUniversityofNorway,Norway
bCatoSenteretRehabilitationCenter,Son,Norway
cDepartmentofPsychology,NTNU,TheNorwegianUniversityofScienceandTechnology,Norway
dManagementEngineering,DTU,TechnicalUniversityofDenmark,Denmark
h i g h l i g h t s
•AmodelformeasurementofFOPinNorwegiansamplesisbuiltandvalidated.
•TheFPQ-NORhadbettermodelfitthanFPQ-IIIandFPQ-SF.
•FPQ-NORissexneutral.
•CulturalvariationsinFOPstresstheneedtoexploreFOPmodelsingivencountry.
•ExplorativeanalysisisimportantwhenapplyingFOPinnewsamples.
a r t i c l e i n f o
Articlehistory:
Received9August2017
Receivedinrevisedform9October2017 Accepted10October2017
Availableonline10November2017
Keywords:
Fearofpain FPQ-III FPQ-SF FPQ-NOR
Exploratoryfactoranalysis Painassessment
a b s t r a c t
Background:Fearofpainishighlycorrelatedwithpainreportandphysiologicalmeasuresofarousal whenpainisinflicted.TheFearofPainQuestionnaireIII(FPQ-III)andTheFearofPainQuestionnaire ShortForm(FPQ-SF)areself-reportinventoriesdevelopedforassessmentoffearofpain(FOP).Aprevious studyassessedthefitoftheFPQ-IIIandtheFPQ-SFinaNorwegiannon-clinicalsampleandprovedpoor fitofbothmodels.ThisinspiredtheideaoftestingthepossibilityofaNorwegianFOP-model.
Aimsandmethods:ANorwegianFOP-modelwasexaminedbyExploratoryFactorAnalysis(EFA)ina sampleof1112healthyvolunteers.Then,themodelfitoftheFPQ-III,FPQ-SFandtheNorwegianFOP- model(FPQ-NOR)werecomparedbyConfirmatoryFactorAnalysis(CFA).Sexneutralitywasexploredby examiningmodelfit,validityandreliabilityofthe3modelsamongstmaleandfemalesubgroups.
Results:TheEFAsuggestedeithera4-,a5-ora6-factorNorwegianFOPmodel.Theeigenvaluecrite- rionsupportedthesuggested6-factormodel,whichalsoexplainedmostofthevarianceandwasmost interpretable.ACFAconfirmedthatthe6-factormodelwasbetterthanthetwo4-and5-factormodels.
Furthermore,theCFAusedtotestthefitoftheFPQ-NOR,theFPQ-IIIandtheFPQ-SFshowedthatthe FPQ-NORhadthebestfitofthe3models,bothinthewholesampleandinsexsub-groups.
Conclusion:A6-factormodelforexplainingandmeasuringFOPinNorwegiansampleswasidentified andtermedtheFPQ-NOR.Thisnewmodelconstitutedsixfactorsand27items,conceptualizedasMinor, Severe,Injection,Fracture,Dental,andCutPain.TheFPQ-NORhadthebestfitoverallandinmale-and femalesubgroups,probablyduetocross-culturaldifferencesinFOP.
Implications:ThisstudyhighlightstheimportanceonexploratoryanalysisofFOP-instrumentswhen appliedtodifferentcountriesorcultures.AstheFPQ-IIIiswidelyusedinbothresearchandclinical settings,itisimportanttoensurethatthemodelsconstructvalidityishigh.Countryspecificvalidation ofFOPinbothclinicalandnon-clinicalsamplesisrecommended.
©2017ScandinavianAssociationfortheStudyofPain.PublishedbyElsevierB.V.Allrightsreserved.
∗ Correspondingauthorat:DepartmentofPsychology,UniversityofTromsø,N- 9037Tromsø,Norway.
E-mailaddress:sara.m.vambheim@uit.no(S.M.Vambheim).
1. Introduction
Measuringfearofpain(FOP)ischallengingduetothemulti- facetedandsubjectivenatureofbothfearandpain.Developing measurement inventoriesapplicable across sex and cultures is https://doi.org/10.1016/j.sjpain.2017.10.009
1877-8860/©2017ScandinavianAssociationfortheStudyofPain.PublishedbyElsevierB.V.Allrightsreserved.
demandingduetopsychosocialandculturaldifferencesthatcan influencetheunderstandingofandresponsestoFOP-items.This issuehasshowntobesalientinthecross-culturalapplicationof theFearofPainQuestionnaireIII(FPQ-III)[1–7].Thecurrentstudy thereforesoughttotestifrevisingcurrentFOP-modelscouldhelp explainFOPintheNorwegianpopulationbetterthantheexisting FPQ-IIIandFPQ-SF.
TheFPQ-IIIwasdevelopedbyMcNeilandRainwater[2].The questionnairehasbecomewidelyused,butstudiesshowvarying levelsofvalidityandconsistency.TheFearofPainQuestionnaire ShortForm(FPQ-SF)wasmorerecentlysuggestedbyAsmundson andcolleagues[8],asanalternativeandsexneutralquestionnaire forFOP-measurements.TheFPQ-SFhasreceivedlittleattention, andthus,littleknowledgeaboutthescale’sreliabilityandvalidity exist.InarecentstudytheFPQ-IIIandtheFPQ-SFwerecompared [6].Thedatawerederived fromaNorwegiansampleofhealthy volunteers,andtheresultsrevealedthatnoneofthemodelshad goodfit.However,theFPQ-SFhadabetterfitoverall,compared totheFPQ-III.Comparisonofthetwomodels’applicabilityacross sexrevealedthattheFPQ-IIIhada betterfitformales,whereas theFPQ-SFhadabetterfitforfemales.Thus,questioningthetwo models’sexneutrality.Invarianceacrosssexisrecommendedfor optimizingmeasurementinventories[8].Thepresentstudythere- foreaimedto:a)testthepossibilityofa NorwegianFOP-model (FPQ-NOR),b)comparetheFPQ-NORagainsttheFPQ-IIIandthe FPQ-SF,andc)evaluatethethreemodels’fitamongstmale and femalesubgroups.WehypothesizedthattheFPQ-Norwaywould havethebestoverallfitanddisplaymostsexneutralityamongst thethreemodels.Furthermore,wehypothesizedthattheFPQ-SF woulddisplaymoresexneutralitythantheFPQ-III.
2. Methods 2.1. Participants
Intotal1112healthyrespondentswereincludedinthisstudy (485males,18–40years(Mage=23.5,SD=4.1)and627females, 18–40years(Mage=22.3,SD=3.6).Thesubjectswerescreenedfor medicalhistoryofseriousdiseasesorinjuriespriortoinclusion.
Somaticandpsychiatricdisorders,medicationuseandpregnancy ledtoexclusion.TherespondentshadtospeakNorwegiandueto useofNorwegianquestionnaires,instructionsandconsentform.
Datafrom10differentstudy-sampleswerepooled.Allparticipants filledin theFPQ-IIIand aninformedconsent form.Thestudies wereapprovedbytheRegionalCommitteeforMedicalResearch Ethics North Norway (project numbers: 2013/966; 2012/1888;
2610.00001; 49/2005; 5.2006.2452; 20277; 17/2006; 30/2008;
31/2008).
SPSSversion24wasusedtorandomlydividethewholesample intotwosamplesbyrandomsplit,inpreparationofthefactoranal- ysis.Sample1included570participants[255males,18–40years (Mage=23.3;SD=4.0)and315females,18–40years(Mage=22.2;
SD=3.7)],andthissub-samplewasappliedintheEFA.Sample2 included542participants[230males,18–40years (Mage=23.8;
SD=4.3)and312females,18–40years(Mage=22.4;SD=3.4)],and thissub-sampleprovidedanindependentsampleforconfirming proposedfactorstructuresrevealedbytheEFAaswellastesting themodelfitofthenewlydevelopedFPQ-NOR,theFPQ-IIIandthe FPQ-SF.
2.2. Measures
TheFearofPainQuestionnaireIIIassessesfearrelatedtopain, andisusedinbothbasic[9]andappliedresearch[10].Thescalehas 30items,eachpresentingasituationinvolvingpain.Responders
score theirFOP foreach item on a 5-pointLikert scale(1=not afraidat all,5=extremelyafraid).The FPQ-IIIhasthree factori- allyderivedsubscales:Severepain(havingaterminalillnessthat causesyoudailypain),Minorpain(burningyourfingers)andMed- icalpain(receivinganinjectioninyourarm).Eachofthesubscales has10items.ANorwegianversionoftheFPQ-III,translatedinto NorwegianbyLybyandcolleagues[9],wasadministeredtothe participantsincludedinthepresentstudy.
TheFearofPainQuestionnaireShortFormisarevisedversion oftheFPQ-III,reducedto20items,andextendedto4subscales:
Severe,Minor,Injection(havinganinjectioninthehip)andDental pain(havingatoothdrilled).TheSeverepainsubscalehas6items, theMinorpainsubscalehas8items,andtheInjectionandDental painsubscalesbothhave3items.SimilarlytotheFPQ-III,scoreson theFPQ-SFareindicatedona5-pointLikertscale.
2.3. Procedure
Responderswereundergraduatestudents recruitedfromthe UniversityofTromsø,TheArcticUniversityofNorway,UiT.Respon- dershadallparticipatedinvariouspainstudiesandfilledinthe FPQ-IIIandawritteninformedconsentformaspartoftheexper- imentalprocedure,priortopaintesting.Paindataobtainedfrom theexperimentsarepublishedelsewhere[9,11–16].
2.4. Statisticalanalyses
EFAwasperformedusingSPSSversion24.CFAwasperformed usingAMOS21.Sample1wasappliedintheEFA.Sample2was appliedintheCFA.EFAwithDirectoblim(oblique)rotationwas usedtoexploretheNorwegianFOPmodel.CFA(maximumlikeli- hoodestimation)wereappliedtoconfirmthemodelrevealedin theEFAandtestthefitoftheFPQ-III,FOP-SFandtheNorwegian FOPmodel.Furthermore,CFAwasalsoappliedtotestthefitamong maleandfemalesub-groupsinSample2.Thefitofthesemodels wasevaluatedbythe2/degreesoffreedomratio,therootmean squareerrorofapproximation(RMSEA),thegoodness-of-fitindex (GFI),andthecomparativefitindex(CFI).Traditionally,agoodfit modelshouldhave2:1or5:12/degreesoffreedomratio,GFI>.90, CFI>.90(preferably>.95),andRMSEA<.08or.10(preferably<.05) indices[17,18].Lastly,Cronbach’salphavaluesforthefactorsinthe NorwegianFOPmodelwerecalculated,aswellasthecorrelation betweensum-scoresoffactorsintheNorwegianFOPmodel.
3. Results
3.1. FactorstructureintheNorwegiansample
Directoblimin(oblique)rotationwasusedsincethecorrelation between the factors ranged from 0.150 to 0.486. The Kaiser- Meyer-Olkinmeasureverifiedthatthesamplewasadequatefor theanalysis(.886).Bartlett’stestofsphericityx2(435)=6975.157, P>.001 indicated that the correlations between the FPQ items were sufficiently high for an EFA. Initial factor structure was assessedwith eigenvalues>1 andCatell’s screetest. Thescree- plot was slightly ambiguous and revealed either a 4-, a 5- or a 6-factor Norwegian FOP model. Eigenvalue>1 supportedthe 6-factormodel,howeveraParallelAnalysissupportedthe4-factor model. The 6-factor structure was found most interpretable, howevertoconfirmthemodel,aCFAonSample2wasperformed totestmodel fit ofthe4-,the5- andthe6-factormodels.The 6-factor model had the best fit (6-factor: 2/df=692.178/194, GFI=.898, CFI=.887, RMSEA=.069 (.063–.074), ECVI=1.498 (1.356–1.653);5-factor:2/df=1509.34/340,GFI=.826,CFI=.790, RMSEA=.080 (.076–.084), ECVI=3.034 (2.818–3.263); 4- factor: 2/df=1168.055/293, GFI=.854, CFI=.830, RMSEA=.074
(.070–.079),ECVI=2.373(2.186–2.575).Thus,neitherthe3-factor structureoftheFPQ-IIInorthe4-factorstructureoftheFPQ-SF wassupportedbytheEFA.The6-factormodelexplained56.86%
ofthevariance.Loadingslessthan0.3wereomittedforthesake ofclarity.Thisresultedinremovalofitem7(hittingtheelbow), 20 (stitchesin thelip) and 27 (vomiting afterfoodpoisoning).
Factorloadingsofthe6-factorstructurearedisplayedinTable1.
Itemsloadingonthesamefactorconstitutesixdifferentfactors, conceptualizedasMinor,Severe,Injection,Fracture,Dental,and CutPain.
3.2. Inter-correlationsandreliabilityanalysisoftheNorwegian FOPmodel
Inter-correlationsandalphavaluesofthefactorscanbeseenin Table2.Allcorrelationsweresignificantatthe0.01level.Thecorre- lationbetweentheMinorfactorandtheCutfactorwerehigherthan betweenanyoftheotherfactors(−.552).FractureandSeverealso hadahighcorrelation(−.539).Thelowestcorrelationwasbetween InjectionandSevere,FractureandInjection,andFractureandDen- tal.Allfactorshadacceptablyhighalphavalues,>0.7[19],showing goodinternalconsistency.Alphavaluesareaffectedbythenumber
Table1
FactorstructureandloadingsoftheFPQitems.
FPQitems Factors
M S I F D C
24soapintheeyes .764
22shavingcut .514
23hotdrink .510
21removefootwart .484
12burnfingers .464
15removesplinterinfoot .457
28sandeyes .429
30musclecramp .381
13breakneck .743
1caraccident .633
25terminalillness .625
5heavyobjectinthehead .614
10falldownstairs .565
9slamcardooronthehand .454 16removeparticlefromeye .323 18faceburnedbycigarette .306
11injectionarm .906
14injectionhip .771
8bloodsample .760
3breakarm −.851
6breakleg −.787
29toothdrilled −.756
26toothpulled −.711
17injectionmouth −.306
4cuttongueonanenvelope −.900
19paper-cutonafinger −.572
2bitethetongue −.437
Note.Principalaxisfactoring,rotationmethod:ObliminwithKaiserNormalization.
Loadingslowerthan.03wereomittedfortheforthesakeofclarity.M=minor, S=severe,I=injection,F=fracture,D=dental,C=cut.
Table2
Inter-correlationsandalphavalues.
M S I F D C Alphavalues
1.000 .793
.401** 1.000 .806
.344** .167** 1.000 .847
−.284** .539** .138** 1.000 .914
.441** .294** .495** .192** 1.000 .719
.552** .325** .214** .358** .351** 1.000 .759
.887(wholescale) Note.M=minor,S=severe,I=injection,F=fracture,D=dental,C=cut,**=.01.
ofitemsinafactor[19].However,theFracturefactorwithonly twoitemsstillshowedthehighestinternalconsistency,whereas theMinorandDentalfactorshadthelowestinternalconsistency (seeTable2).ThealphavaluesoftheMinor,–theDental,–andthe Cutfactorsareslightlybelowthealphavaluesofthefactorsinthe twopreviousstudies.McNeilandcolleagues[2]lowestalphavalue was0.87,Asmundsonandcolleagues[8]lowestalphavaluewas 0.83andthelowestalphavalueinthepresentstudywas0.719.
3.3. Fitofthethreemodels
CFA wasconducted to test thefit of the FPQ-III model, the FPQ-SF and theNorwegian6-factormodel revealedin theEFA.
Thefactorstructuresrespectivelyshowedthree,fourandsixfac- tors that inter-correlated to explain FOP. No items loaded on more than one factor. Traditionally, a good fit model should have2:1or5:12/degreesoffreedomratio,RMSEA<.08or.10 (preferably<.05), GFI>.90, ECVI-lower values indicate a closer fit, and CFI>.90 (preferably>.95) indices [17,18,20]. The good- ness of fit indices suggests satisfactory, but not perfect fit for the Norwegian 6-factor model in the whole sample (6-factor model; 2/df 692.178/194, RMSEA=.069 (.063–.074), GFI=.898, ECVI=1.498 (1.356–1.653), CFI=.887, see Table 3). However lower fit for the FPQ-III and the FPQ-SF, with a slightly bet- terfitfortheFPQ-SF(FPQ-3:2/df=2143.934/402;RMSEA=.089 (.086–.093), GFI=.782, EVCI=4.196 (3.3935–4.471), CFI=.702;
FPQ-SF:2/df=858.591/164,GFI=.860,RMSEA=.088(.083–.094), ECVI=1.757(1.595–1.934),CFI=.822;seeTable3).Furthermore, thethreemodelswereappliedtothedataconsistingofsubgroups ofsex(seeTable3).Resultssuggestthatthe6-factormodelhad thebestfitofthethreemodelsamongbothmalesandfemales.The FPQ-IIIwasgenerallylessfittingthanthetwootherfactormodels.
Allmodelshadbetterfitamongfemalesthanmales.
4. Discussion
TheinvestigationintothepossibilityofaNorwegianFOP-model wasspurredbypreviousfindingsthatshowedpoorfitoftheFPQ- III [1,6,21]and the FPQ-SF [6]. EFA disclosedeither a 4-, a 5-, ora6-factormodel.Eigenvalue>1supportedthe6-factormodel.
AlthoughtheParallelAnalysissupportedthe4-factormodel,the subsequentCFAsconfirmedthe6-factormodel.Removalofitems loadingbelowthepredefinedcriteriaresultedina highlyinter- pretable 6-factormodel. The six emerging factors wereMinor, Severe,Fracture,Cut,DentalandInjectionPain.Thisnewmodel, referredtoastheFPQ-NOR,wasthemostsuitedmodelforexplain- ingandmeasuringFOPinthisNorwegiansample.
TheCFAsusedtocomparetheFPQ-IIIandtheFPQ-SFtothe newlydevelopedFPQ-NORrevealedthattheFPQ-NORhadabetter fitthanthepreviouslydevelopedFPQ-IIIandtheFPQ-SF.Thiswas evidentwhenfitindiceswereexaminedoverallandacrossmale andfemalesub-groups.TheresultssuggestthatFOP maydiffer acrossculturesandthereforehighlighttheimportanceofvalidation ofFOP-measures.
4.1. ModelstructureintheFPQ-NOR,theFPQ-IIIandtheFPQ-SF
TheFPQ-NORincluded27itemsloadingon6differentfactors:
Minor,Severe,Injection,Dental,Fracture,andCut.McNeilandRain- water[2]andAsmundsonetal.[8]usedacut-offpointof0.50.A cut-offof0.50wasconsideredtoohighforthepresentstudyasit resultedinmanyremoveditems,lowinterpretability[23–25]and adifferentfactorialsolutionthanpresentedbyMcNeilandRainwa- ter[2]andAmundsonetal.[8].The3-factorstructureidentifiedby McNeilandRainwater[2]includedMinor,SevereandMedicalPain.
Table3 FitindexesfromCFAforallthreemodels. 3factors4factors6factors 2(df)GFIRMSEA(CI)EVCI(CI)CFI2(df)GFIRMSEA(CI)EVCI(CI)CFI2(df)GFIRMSEA(CI)EVCI(CI)CFI Sample2 (n=542)2143.93 (402).7820.089 (0.086–0.093)4.196 (3.935–4.471).702858.59 (164).8600.088 (0.083–0.094)1.757 (1.595–1.934).822692.17 (194).8980.069(0.063–0.074)1.498(1.35–1.65).887 Sex Males (n=230)1259.11 (4020).7260.096 (0.090–0.103)6.049 (5.598–6.533).683538.40 (164).8150.100 (.091–.109)2.753 (2.462–3.077).792472.21 (194).8530.079(0.070–0.088)2.577(2.23–2.28).853 Females (n=312)1500.72 (402).7480.094 (0.089–0.099)5.231 (4.861–5.624).664535.28 (164).8500.85 (0.077–0.093)2.017 (1.804–2.255).826533.21 (194).8680.075(0.067–0.083)2.094(1.88–2.32).863 Note:Goodmodelfitshouldhave2:1or5:12/degreesoffreedomratio,RMSEA<.08or.10(preferably<.05),GFI>.90,ECVI-lowervaluesindicateacloserfit,andCFI>.90(preferably>.95).
Asmundsonandcolleagues[8]didnotfindaMedicalPainfactor, butidentifiedtwonewfactors;DentalandInjectionPain.
FourofthepreviouslyidentifiedFPQ-SFfactors(Minor,Severe, InjectionandDentalPain)alsoappearedinthepresentstudy.More- over, twonewfactors, conceptualizedasFracturePainand Cut Pain,wereuncovered.Bothfactorsincludeditemsloadinghighly onFOP,respectivelywithhighandacceptablehighalphavalues, comprisingindependentfactors.Thus,therearesomedistinctions inmodelstructureandnumberofitemsintheFPQ-III,theFPQ-SF andtheFPQ-NOR.Themoststablefactordistinctionseemstobe betweenMinorandSeverepain.Thismightbeexpected,aspain inabroadsenseisclassifiedonanintensitydimension(i.e.the VisualAnalogueScaleandNumericalRatingScale),andthisdiffer- enceinpainshouldalsobesalientacrosscultures.However,the distinctionbetweentheotherFOP-subscalesisnotverystable,as differentunderlyingFOPstructuresseemtoappearwhenapplying theFPQindifferentcountries.
DifferencesbetweenthethreeFOPmodelswerealsopresent onanitemlevel.Item16(haveaneyedoctorremoveaparticle stuckinyoureye)wasincludedintheSeverePainsubscaleinthe FPQ-NOR.Bycontrast,theFPQ-IIIincludeditem16ontheMedical Painsubscale,whereastheFPQ-SFexcludeditem16.Item15(have adeepsplinterinthesoleofyourfootprobedandremovedwith tweezers)and21(haveafootdoctorremoveawartwithasharp instrument)wereincludedintheMinorPainsubscaleintheFPQ- NOR.BoththeseitemswereincludedintheMedicalPainsubscale intheFPQ-III,whilebothitemswereremovedintheFPQ-SF.More- over,theInjectionPainsubscalewasidenticalintheFPQ-NORand theFPQ-SF,whiletheFPQ-NORDentalPainsubscaleincludedtwo ofthethreeitemsincludedintheFPQ-SFDentalPain.
Theitemsthatloadhighestonagivenfactor canbetermed coreitems.Coreitemsaretheitemsthatexplainthemostofthat specificfactor.WhencomparingtheFPQ-IIItheFPQ-SFandtheFPQ- NOR,somedifferencesbetweenthemodels’coreitemswerefound.
McNeilandRainwater[2]andAsmundsonetal.[8]showeddiffer- entcoreitemsexplainingtheMinorandSeverePainfactorthan thepresentstudy.McNeilandRainwater[2]reportedtwoitems loadingequallyhigh.Inthatstudy,item7(hittingasensitivebone inyourelbow)anditem19(paper-cutonafinger)werethehigh- estloadingitemsontheMinorPainsubscale.Asmundonetal.[8]
partlyreplicatedthisfindingbyalsoreportingthatitem 19was thecoreitemonMinorPainsubscale.Thepresentstudydidnot supportthosefindings,andshowedthatitem24(soapintheeyes) anditem22(shavingcut)werethecoreitems.Infact,item7was oneofthelowloadingitemsinthepresentanalysis,andwasthere- foreremovedfromthemodel.ThecoreMinorPainitemswerenot includedasaMinorPainsubscaleitemintheFPQ-IIIortheFPQ-SF.
Contrarytoourfindings,McNeilandRainwater[2]andAsmund- sonet al. [8]identified thesame coreitem ontheSeverePain subscale:item6(breakingyourleg).Weidentifieditem13(break- ingyourneck)asthecoreSeverePainsubscaleitem.Actually,item 6wasnotincludedintheFPQ-NORSeverePainsubscale.Inthis model,item6constitutedthenewlyconceptualizedFracturePain subscale.However,thepresentstudyreplicatedAsmundsonetal.’s [8]findingonthecoreitemsrepresentingtheInjectionandtheDen- talPainsubscales.Thus,bothmodelstructureandthecoreitemsof thepresentfindingshadmoresimilaritiesandweremoresupport- iveoftheFPQ-SFmodelthantheFPQ-IIImodel.TheFPQ-NORis howeveramoredetailedmodelthantheFPQ-IIIandFPQ-SF,indi- catingthattheNorwegiansampleseparatesbetweenmorepain sub-categoriesthantheDutch,CanadianandAmericansamples.
Itshouldalsobenotedthatthedifferentresultsobtainedinthe presentandpreviousanalysisofFOP-data[2,8]maypartlybedue todifferentstatisticalapproaches.Differentfactorextractionmeth- odsandrotationtechniquesmayexplainwhydifferentmodelsof FOPemergeintheEFAs.McNeilandRainwater[2]appliedPrincipal
ComponentAnalysis(PCA)withorthogonalrotation,whereasthe presentstudyandAsmundsonetal.[8]appliedPrincipalFactor Analysis(PFA)withobliquerotation.PCAandPFAusedifferent factor extractionmethods, and item loadingsbecomehigher in PCAthanin PAFbecauseofhighercommunalityestimates[18].
However,the literaturein the field of factor analysisgenerally recommendsPAFoverPCA[18,26,27].PAFwasthereforechosen fordataanalysisinthepresentstudy.
4.2. Fitofthethreemodelstothedata
TheCFAshowedthattheFPQ-NORhadthehighestfittothe dataofthethreemodels,whiletheFPQ-IIIhadthelowestfit.These resultsconfirmthenecessityofinvestigatingapossibleNorwegian FOP-model,andthehypothesisthatFOPmightlookslightlydiffer- entintheNorwegianthanintheDutch,CanadianandAmerican samples.Different combinationsofsex-and culturaldifferences posechallengesfortheutilizationofone standardizedmeasure ofFOP,applicableacrosscultures.Itisnotsurprisingthatdiffer- entFOPmodelsarefoundindifferentcountriesaspainandfear ofpainare influencedbymultiplefactors,suchasage,sexand genderroleexpectations[11,22,28].Thefactthatthepresent6- factorstructureresemblespreviouslyobtainedfactorstructures, butnotcompletelyconfirmstheneedtoapplyexplorativeanal- ysiswhenaFOPquestionnaireisused.Acountryorpopulation’s factorstructure maybeagood indicatorofwhatsort offearof painthepopulationhas.Therefore,thisinformationmaybeuse- fule.g.whentreatmentprogramsorpreventiveinterventionsare designed.Futurestudieswouldbenefitfromcross-culturalcom- parisonoffearofpainmeasures.
Asmentionedabove,differentcombinationsofsexdifferences mayposechallengesforutilizationofonestandardizedmeasure- mentofFOP.Forexample,thefindingthatsexdifferencesinpain andpain-relatedbehaviorisexplainedbypsychosocialfactorshas beenreportedrepeatedly [28,29].Robinson and colleagues[28]
foundthatbothsexesthoughtmaleswerelesswillingtoreport pain,andthatmaleswerelesssensitiveandmoreenduringofpain, thanfemales.Thus, indicatingthatgenderroleexpectationsare acentralcontributortosexdifferencesinmeasurementsofpain andpain-relatedphenomena,suchasmeasurementsofFOP.Oth- ershavereportedsexdifferencesinFOP,displayedbylowerFOP inmalesthaninfemales[1–6].Thus,therearedifferencesinmale andfemaleresponsestopainandfearofpain,whichmightalsobe salientinFOPmodelsforthesexes.
Inthepresentstudy,thereweresmallsexdifferencesinmodel fit.ThenewlydevelopedFPQ-NORshowednearlysimilarfitfor malesandfemales.Thus,indicatingthattheFPQ-NORexplainsFOP equallywellinmalesandfemales.Sexdifferencesinmodelfitof theFPQ-IIIhavepreviouslybeenfound[6].However,thesefind- ingswerenotreplicatedinthepresentstudy.Asmundsonetal.
[8]reportedthattheFPQ-SFshowedinvarianceacrosssex,butin thepresentandonepreviousstudy[6],somesexdifferenceswere foundwhenapplyingtheFPQ-SF.
4.3. Limitations
AllthesubjectsincludedinthisstudyrespondedtotheFPQ- III.Thisrepresentsapotentialmethodologicallimitation,e.g.the possibility that other results would emerge if the FPQ-SF also hadbeenadministered.Itisthereforerecommendedthatfuture investigationsincludesamplesinwhichbothquestionnairesare administered.Additionally,asonlyhealthyandyoungvolunteers wereincludedinthestudy,thefindingsmaybegeneralizableto youngnon-clinicalsamplesonly.Thepresentstudywasunableto examinedifferencesacrossageduetothesample’shomogeneityin
age.FuturestudiescouldexamineFOPacrossagegroupstouncover potentialdifferencescausedbyage.
4.4. Conclusions
Thisstudyproposesa6-factormodelformeasurementsofFOP inNorwegiansamples,referredtoasTheFearofPainQuestion- naireNorway(FPQ-NOR).CFArevealedthattheFPQ-NORhada betterfittothedatathanboththeFPQ-IIIandtheFPQ-SF.Addi- tionally,theFPQ-NORhadthebestfitacrosssexsubgroups,thus indicatingsexneutrality.Thereasonsforthedifferentmodelsmay bethatcross-culturalvariance influencesFOP,and therebyFOP modelsindifferentcountries. TheFPQ-NORisa detailedmodel includingmoresub-factorstoexplainFOPthantheFPQ-IIIandthe FPQ-SF.Amoredetailedmodelmayenabledifferentiationofdis- tincttypesofFOP,andthusbeusefulindiagnosticcircumstances andforimprovementofclinicalresearch.Thus,thepresentstudy highlightstherelevanceofexplorativeanalysiswhenapplyingthe FearofPainQuestionnairetoanewcountryorculture.FutureFOP- studiesemploying theFPQ-III ortheFPQ-SFcouldbenefit from testingthepossibilityofrevisedFOPmodelswhenexploringFOPin agivencountry.TheFPQ-NORshouldbevalidatedinfuturestudies.
Itwouldalsobeinterestingtotestthemodel’sfactorstructureand psychometricpropertiesinclinicalsamples.
Ethicalissues
Informedconsentforthestudieswererequiredandcollected.
ThestudieswereapprovedbytheRegionalCommitteeforMedical ResearchEthicsNorthNorway.
Conflictofintereststatement
Theauthorsdeclarenoconflictofinterest.
Acknowledgements
ThisstudywassupportedbyagrantfromtheBIALFoundation (186/10)andtheUniversityofTromsø,UiT,Tromsø,Norway.
References
[1]AlbaretMC,SastreMTM,CottencinA,MulletE.TheFearofPainquestionnaire:
factorstructureinsamplesofyoung,middle-agedandelderlyEuropeanpeople.
EurJPain2004;8:273–81,http://dx.doi.org/10.1016/j.ejpain.2003.09.005.
[2]McNeilDW,RainwaterAJ.DevelopmentoftheFearofPainQuestionnaire-III.J BehavMed1998;21:389–410,http://dx.doi.org/10.1023/A:1018782831217.
[3]RoelofsJ,PetersML,DeutzJ,SpijkerC,VlaeyenJWS.TheFearofPainQuestion- naire(FPQ):furtherpsychometricexaminationinanon-clinicalsample.Pain 2005;116:339–46,http://dx.doi.org/10.1016/j.pain.2005.05.003.
[4]Solé E, Castarlenas E, Sánchez-Rodríguez E, Galán S, de la Vega R, Jensen MP, Miró J. The reliability and validity of the Spanish ver- sion of the Fear of Pain Questionnaire. J Health Psychol 2017:1–11, http://dx.doi.org/10.1177/1359105316686669,1359105316686669.
[5]VambheimSM,ØienRA.Sexdifferencesinfearofpain:itemlevelanalysisof theFPQ-III.JPainRes2017;10:825–31.
[6]VambheimSM,LybyPS,AslaksenPM,FlatenMA,ÅsliO,MartinussenLM.The FearofPainQuestionnaireIIIandtheFearofPainQuestionnaireShortForm:a confirmatoryfactoranalysis.JPainRes2017;10:1871–8.
[7]WijkAJ, Hoogstraten J. Dutchtranslation of theFear of PainQuestion- naire:factorstructure,reliabilityandvalidity.EurJPain2006;10:479–86, http://dx.doi.org/10.1016/j.ejpain.2005.06.008.
[8]AsmundsonGJG,BovellCV,CarletonNR,McWilliamsLA.TheFearofPain Questionnaire-ShortForm(FPQ-SF):factorialvalidityandpsychometricprop- erties.Pain2008;134:51–8,http://dx.doi.org/10.1016/j.pain.2007.03.033.
[9]Lyby PS, Aslaksen PM, Flaten MA. Is fear of pain related to placebo analgesia? J Psychosom Res 2010;68:369–77, http://dx.doi.org/10.1016/
j.jpsychores.2009.10.009.
[10]HoviSL,LauriS.Patients’andnurses’assessmentofcancerpain.EurJCancer Care1999;8:213–9.
[11]AslaksenPM, BystadM,Vambheim SM,FlatenMA.Gender differencesin placeboanalgesia:event-relatedpotentialsandemotionalmodulation.Psycho- somMed2011;73:193–9,http://dx.doi.org/10.1097/PSY.0b013e3182080d73.
[12]Lyby PS, Aslaksen PM, Flaten MA. Variability in placebo analgesia and the role of fear of pain—an ERP study. Pain 2011;152:2405–12, http://dx.doi.org/10.1016/j.pain.2011.07.010.
[13]Lyby PS, Forsberg JT, Åsli O, Flaten MA. Induced fear reduces the effectiveness of a placebo interventionon pain. Pain2012;153:1114–21, http://dx.doi.org/10.1016/j.pain.2012.02.042.
[14]AslaksenPM,LybyPS.Fearofpainpotentiatesnocebohyperalgesia.JPainRes 2015;8:703–10,http://dx.doi.org/10.2147/JPR.S91923.
[15]Bjørkedal E, Flaten MA. Interaction between expectancies and drug effects: an experimental investigation of placebo analgesia with caf- feine as an active placebo. Psychopharmacology 2011;215:537–48, http://dx.doi.org/10.1007/s00213-011-2233-4.
[16]BjørkedalE,FlatenMA.Expectationofincreasedanddecreasedpainexplainthe effectofconditionedpainmodulationinfemales.JPainRes2012;5:289–300, http://dx.doi.org/10.2147/JPR.S33559.
[17]HuLT,BentlerPM.Cutoffcriteriaforfitindexesincovariancestructureanalysis:
conventionalcriteriaversusnewalternatives.StructEqModel2009;6:1–55, http://dx.doi.org/10.1080/10705519909540118.
[18]RussellDW.Insearchofunderlyingdimensions:theuse(andabuse)offactor analysis.PerSocPsycholBull2002;28:1629–46.
[19]Cortina JM. What is coefficient alpha? An examination of theory and applications. J Applied Psych 1993;78:98–104, http://dx.doi.org/10.1037/
0021-9010.78.1.98.
[20]BrowneMW,CudeckR.Alternativewaysofassessingmodelfit,vol.154.Sage FocusEditions;1993.p.136.
[21]OsmanA,BreitensteinJL,BarriosFX,GutierrezPM,KopperBA.TheFearofPain Questionnaire-III:furtherreliabilityandvaliditywithnonclinicalsamples.J BehavMed2002;25:155–73,http://dx.doi.org/10.1023/A:1014884704974.
[22]CarrTD,LemanekKL,ArmstrongFD.Painandfearratings:clinicalimpli- cationsofageandgenderdifferences.JPainSymptomManage 1998;15:
305–13.
[23]CostelloAB,OsbornJB.Bestpracticesinexploratoryfactoranalysis:fourrec- ommendationsforgettingthemostoutofyouranalysis.PARE2005;10.
[24]FieldA.DiscoveringstatisticsusingSPSS.3rded.London:SAGEPublications Ltd;2009.
[25]KlineP.Aneasyguidetofactoranalysis.London:Routledge;1994.
[26]ReiseSP,WallerNG,ComreyAL.Factoranalysisandscalerevision.Psych Assessment2000;12:287–97.
[27]WidamanKF.Commonfactoranalysisversusprincipalcomponentanaly- sis:differentialbiasinrepresentingmodelparameters?MultivarBehavRes 1993;28:263–311.
[28]RobinsonME,RileyJL,MyersCD,PapasRK,WiseEA,WaxenbergLB,Fillingim RB.Genderroleexpectationsofpainrelationshiptosexdifferencesinpain.J Pain2001;5:251–7.
[29]HornME,AlappattuMJ,GayCW,BishopM.Fearofseverepainmediatessexdif- ferencesinpainsensitivityresponsestothermalstimuli.PainResTreat2014:7, http://dx.doi.org/10.1155/2014/897953.
