Validation of sun exposure and protection index
(SEPI) for estimation of sun habits
H. Detert, S. Hedlund, Chris Anderson, Y. Rodvall, Karin Festin, D. C. Whiteman and
Magnus Falk
Linköping University Post Print
N.B.: When citing this work, cite the original article.
Original Publication:
H. Detert, S. Hedlund, Chris Anderson, Y. Rodvall, Karin Festin, D. C. Whiteman and Magnus
Falk, Validation of sun exposure and protection index (SEPI) for estimation of sun habits, 2015,
Cancer Epidemiology, (39), 6, 986-993.
http://dx.doi.org/10.1016/j.canep.2015.10.022
Copyright: 2015 The Authors. Published by Elsevier
http://www.elsevier.com/
Postprint available at: Linköping University Electronic Press
Validation
of
sun
exposure
and
protection
index
(SEPI)
for
estimation
of
sun
habits
H.
Detert
a,1,
S.
Hedlund
a,1,
C.D.
Anderson
b,
Y.
Rodvall
c,
K.
Festin
a,
D.C.
Whiteman
d,
M.
Falk
a,*
aDivisionofCommunityMedicine,PrimaryCare,DepartmentofMedicineandHealthSciences,LinköpingUniversity,S-58183Linköping,Sweden b
DivisionofDermatology,DepartmentofClinicalandExperimentalMedicine,LinköpingUniversity,S-58183Linköping,Sweden c
DepartmentofPublicHealthSciences,KarolinskaInstitutet,S-17177Stockholm,Sweden d
QIMRBerghoferMedicalResearchInstitute,LockedBag2000,RoyalBrisbaneHospital,Qld4029Herston,Australia
ARTICLE INFO Articlehistory: Received11March2015
Receivedinrevisedform20October2015 Accepted23October2015
Availableonline9November2015 Keywords: Skincancer Sunhabits Sunprotection Ultravioletexposure Questionnaire ABSTRACT
Background:InbothSwedenandAustraliahighincidenceratesofskincancerhavebecomeamajorhealth problem.Inpreventionandriskcommunication,itisimportanttohavereliablewaysforidentifying peoplewithriskysunhabits.InthisstudythevalidityandreliabilityofthequestionnaireSunExposure ProtectionIndex(SEPI),developedtoassessindividual’ssunhabitsandtheirpropensitytoincreasesun protectionduringroutine,oftenbrief,clinicalencounters,hasbeenevaluated.Theaimofourstudywas to evaluatevalidityandreliabilityof theproposedSEPIscoring instrument, intwocountries with markedlydifferentultravioletradiationenvironments(SwedenandAustralia).
Method:TwosubpopulationsinSwedenandAustraliarespectivelywereaskedtofillouttheSEPItogether withthepreviouslyevaluatedReadinesstoAlterSunProtectiveBehaviourquestionnaire(RASP-B)and theassociatedSun-protectiveBehavioursQuestionnaire.Totestreliability,theSEPIwasagainfilledout bythesubjectsonemonthlater.
Results:ComparisonbetweenSEPIandthequestionsintheSun-protectiveBehavioursQuestionnaire, analyzedwithSpearman’sRho,showedgoodcorrelationsregardingsunhabits.Comparisonbetween SEPIandRASP-BregardingpropensitytoincreasesunprotectionshowedconcurrentlylowerSEPImean scoresforactionstage,butnodifferencebetweenprecontemplationandcontemplationstages.TheSEPI test-retest analysis indicated stability over time. Internal consistency of the SEPI, assessed with Cronbach’salphaestimationshowedvaluesmarginallylowerthanthedesired>0.70coefficientvalue generallyrecommended,andwassomewhatnegativelyaffectedbythequestiononsunscreenuse,likely relatedtotheclassic“sunscreenparadox”.ThereweresomedifferencesintheperformanceoftheSEPI betweentheSwedishandAustraliansamples,possiblyduetotheinfluenceof“available”sunlightand differingattitudestobehaviourandprotection“athome”andonvacation.
Conclusions:SEPIappearstobeastableinstrumentwithanoverallacceptablevalidityandreliability, applicableforuseinpopulationsexposedtodifferentUVRenvironments,inordertoevaluateindividual sunexposureandprotection.
ã2015TheAuthors.PublishedbyElsevierLtd.ThisisanopenaccessarticleundertheCCBY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).
1.Introduction
Formanyyears,theincidenceofskincancerhasbeenincreasing inwesternsocieties,notleastnorthernEurope[1,2].InSweden,for example,malignantmelanoma(MM),themostlethalskincancer form,hasbecomethemostrapidlyincreasingmalignancyduring recentdecadesandwasin2013thefifthmostcommontypeof canceramong womenandthesixthmostcommontypeamong men.Additionally,nonmelanomaskincancer(NMSC),includedin the cancer registry in Sweden, has become the second most
*Correspondingauthor.
E-mailaddresses:hedde211@student.liu.se(H. Detert),
sarhe388@student.liu.se(S. Hedlund),chris.anderson@regionostergotland.se
(C.D. Anderson),ylva.rodvall@ki.se(Y. Rodvall),karin.festin@liu.se(K. Festin),
David.Whiteman@qimrberghofer.edu.au(D.C. Whiteman),
magnus.falk@regionostergotland.se(M. Falk). 1
Theseauthorscontributeequallytothestudy.
http://dx.doi.org/10.1016/j.canep.2015.10.022
1877-7821/ã2015TheAuthors.PublishedbyElsevierLtd.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).
ContentslistsavailableatScienceDirect
Cancer
Epidemiology
The
International
Journal
of
Cancer
Epidemiology,
Detection,
and
Prevention
frequentcancerformforbothwomenandmen[1].InAustralia, whichhastheworld’shighestincidenceratesforallskincancers, MMis thethird mostcommoncancerformdiagnosed forboth women and men, and during the years 1991–2009 the age standardisedincidenceofMM,inmen,increasedwith42percent, andwith18percentinwomen[3].NMSCisnotgenerallyrecorded incancerregistersinAustraliabutisneverthelessbyfarthemost frequentlydiagnosedcancerforbothmenandwomen[4].
Froma preventive perspective, the increasingincidence has turnedthefocustowardssunexposurehabits,andhowtomodify people’sbehaviourinthesun,sinceultravioletradiation(UVR)is notonlythemainknowncauseofskincancerdevelopment[5,6], but also the one that is most amenable to change [7]. Other important risk factors in the development of skin cancer are pigmentation phenotype [8], genetic background [5], common nevicount and atypical nevicount [9,10].While thehigh skin cancerrates in Australia are entirely consistent withits sunny climateandlocationclosetotheequator,thehighincidencerates inSwedenareremarkablegiventhehighlatitudeandmarkedly lower number of average daily sunshine hours. The probable explanationforthisisthefactthattheSwedishpopulationhasone oftheworld’smostpronouncedsun-seekingbehaviour,whereas theAustralianpopulationhasbeeneducatedfordecadestotryto protect itself from the sun [11]. Prevention of excessive UVR exposureisimportantthroughoutlife,notonlysincefrequentsun exposureandsunburns(especiallyinearlylife)hasbeenfoundto increasetheriskfordevelopmentofMMandbasalcellcarcinoma (BCC)[12,13],butalsosincepopulationsinwesternsocietiesarein generalgetting older, withincreasedlevels ofaccumulatedsun exposureduringlife.Preventivemeasuresneedthereforetofocus bothonminimizingnumbersofsunburnsandalsothecumulative rateofsunexposureinallagegroups[14–16].Themostfrequently usedsunprotection,bothinAustraliaandworldwide,istoapplya sunscreen, whereas the recommended ways of protection are coveringupwithclothes,stayingintheshade,wearinga broad-brimmedhatandavoidingthesunbetween11amand3pm[11,17– 20].
Notleastwhenit comes toprevention, reliablemapping of individualsunexposureaswellasattitudestoandpracticeofsun protection is highly desirable. Despite much activity, no gold standard for measurement of sun exposure habits exists. Furthermore, many questionnaires are extensive and time consuming,hinderingbroad clinicaluptake.Somestudieshave looked at objective methods for assessing exposure such as observations or UV-indicators [20,21]. Despite an inevitable elementof uncertainty and recall bias, however, self-reported measures of ultraviolet exposure have been found to be surprisingly reliable when compared with actual exposure assessedbyobservationalmethods[21].Examplesofsun-related questionnairesaretheSunprotectionbehaviourscale(SPBS)[22], andReadinesstoAlterSunProtectiveBehaviourRASP-B[23],both basedonthetranstheoreticalmodelofbehaviourchange(TTM). Wepreviouslypresentedascoringmodelbasedonacombination ofLikertscalescoresformapping sunexposureandprotection practices, and TTM for mapping readiness to increase sun protection[24].Basedonthemodel,wehavenowdevelopeda combinedscoringinstrumentnamedSunExposureand Protec-tionIndexSEPI,intendedforuseinpatient-doctorinteractionsin clinical practice [25,26], as well as for evaluating preventive interventions[24].
Theaimofthepresentstudywastoevaluatethevalidityand reliabilityoftheSEPIscoringinstrument,intwocountrieswith differentUVRenvironments.Inaddition,wetestedtheutilityof theSEPI toexplore possibledifferences insun exposurehabits betweenpopulations—inthispaperSwedenandAustralia.
2.Materialandmethods
2.1.Studypopulations
The study was performed in Brisbane, Australia, and in Linkoping, Sweden, in September to December 2013. In each country, participants were sampled from two subpopulations, namely primary health care (PHC) patients and university students.Theinitialaimwastorecruit150participantsineach subpopulationrespectively,asamplesizebasedontheoutcomeof thepreviouslyperformedpilotstudydescribingthemodel[24], comprising approximately 100 subjects in each group, with a marginforpossibledrop-outs.
2.1.1.Primaryhealthcarepatients
ThesamplesofPHCpatientswererecruitedfromtwotypical PHC practices in Brisbane and Linköping, respectively. At registrationinthereception,theSEPIquestionnairewashanded tothepatients,together withawritteninformationsheetabout thestudy,andarequesttovoluntarilyparticipate.Patientswilling todososignedawrittenconsentformwhichwasenclosedwith the questionnaire,and then filled-out thequestionnaire, either whilesittinginthewaitingroom,orlaterathome.Inadditionto SEPI, the participants also completed a previously validated questionnaire,bymeansoftheRASP-Bandtheassociated Sun-protectiveBehavioursQuestionnaireusedinthevalidationprocess of the latter [23]. After four weeks, participants were sent a repeated SEPI questionnaire to be filled-out, together with a prepaidenvelopeandaninformationletterwithareminderofthe studyandarequesttoreturnthecompletedquestionnairebymail.
2.1.2.Students
The student sample in Australia consisted of third year psychology students and first year engineering mathematic studentsatQueenslandUniversityofTechnology(QUT).InSweden the population consisted of second and third year psychology studentsandsecondyearengineeringappliedphysicsstudentsat LinköpingUniversity(LiU).
Thestudentsampleswererecruitedbyvisitingtwolecturesin BrisbaneandthreelecturesinLinköpingwhere,afterabriefverbal introductionandinformation,thestudentsreceivedthe informa-tion sheet,consentformwithcontact detailsand the SEPI and RASP-B/Sun-protective Behaviours Questionnaire, which they thereafterhandedin.Thetest-retestprocedureafterfourweeks wasthesameasforthegroupofPHCpatients.
2.1.3.Inclusionandexclusioncriteria
Inallfourstudysubpopulations,age18yearswasaninclusion criterion.Exclusioncriteriawereindividualswithlimited autono-my or impaired cognitive abilities. We did not impose any exclusion criteria relating to conditions that might affect sun exposurehabits(e.g.photodarmatosesetc)aswesoughttorecruit samples that reflected unselected populations, namely PHC patients and students. No remuneration for participation was offered.
2.2.Questionnaire
2.2.1.SEPI
The SEPI scoring instrument consists of two sections; one includingeightquestionsappraisingsunhabitsandsunprotection behaviour,andoneincludingfivequestionsassessingreadinessto increasesunprotection(seeappendix).Thecontentsofthetwo sectionsweredevelopedfrompreviousstudies[27–29]andthe questionitemsusedinthese,andwerethen,inafirststep,selected and processed among a group of experts within the field,
comprisingdermatology,epidemiology,publichealthandprimary healthcare,tocoverthedifferentareasofthescore.Inasecond step,thesuggestedinstrumentwasforwardtranslatedfromthe original Swedish version into the English language, and the consistencyoftheproducedEnglishversionre-comparedwiththe originalbyanativeEnglishspeakerskilledinbothlanguages.Ina thirdstep,thetwolanguageversionsoftheinstrumentswerethen presented, further discussed and evaluated in two seminar sessionswithtwo groups of primaryhealthcare clinicians; one inAustraliaandoneinSweden,respectively.Theprocessresulted inequivalentquestionformulationsforbothcountryquestionnaire versions,exceptforthequestiononvacationalsunexposure(inthe Australianversion:“How oftendo you takea holidaywiththe intentionofspendingmoretimeinthesun?”),forwhichtravelto sunnyresorts abroad were referred to in the Swedish version (“Howoftendoyoutravelabroadtocountrieswithstrongsunlight (forexampletosunnyresorts)?”),sincethelatterconstitutesan important source of UV exposure especially during the winter seasoninSweden.Subsequentbackwardtranslationpriortoalater studygaveanessentiallyidenticalSwedishversion.
Each partoftheSEPI resultsina score.PartI,mapping sun exposure/protectionhabits,includeseightquestionsbasedon five-gradeLikertscalescores(0–4points),resultinginatotalscoreof0– 32points,reflectinganincreasingriskexposure.PartII,mapping readinesstoincreasesunprotection,includesfivequestionsscored from0to4pointsbasedonthedefinedstagesofchangeaccording tothe TTM (maintenance,action, preparation,contemplation and precontemplationstage),resultinginatotalscoreof0–20points, reflectingadecreasingpropensitytoincreasesunprotection.Thus, insummary,ahighscoreinbothpartsreflectsahighlevelofsun exposure,andalowpropensitytochangeit.
2.2.2.RASP-B/Sun-protectiveBehavioursQuestionnaire
TheRASP-Bquestionnaireconsistsoftwelvequestions assess-ingpropensitytoincreasesunprotection,accordingtotheTTM. UnlikepartIIinSEPI,however,eachquestionreferstoaspecific stage of change (precontemplation,preparation or action stage), distributed as four questions for each stage, instead of each question assessing stage of change for specific aspects of UV exposure/protection.CompletingtheRASP-Bresultsinonesingle dominantstageofchangeforeach individual,notreferringtoa specificbehaviour(e.g.sunscreenuse).Inthevalidationprocessof RASP-B,thecomplementarySun-protectiveBehaviours Question-nairewasused,consistingof14questionsexploringcurrentsun exposure habits/sun protection behaviour, based on five-grade Likertscaleresponses[23].
Fordemographicinformation,ageandgenderwererecordedin thequestionnaire.
2.3.Testingofvalidity
For partIof SEPI, mappingcurrentsunexposure habits,we calculatedSpearman’srhotoestimatethecorrelationbetweenthe eightquestionsinSEPIandeachoftheoneormorequestionsinthe SunprotectivebehavioursquestionnaireofRASP-B.Acorrelation coefficient value of 0.10-0-29 was seen as poor correlation, between0.30–0.49asmediumcorrelationand0.50–1.00asgood correlation [30]. A level of P<0.05 was set as statistically significant.
For part II of SEPI, assessing propensity to increase sun protection, correlation with each of the questions in the Sun protective behaviours questionnaire was also explored using Spearman’s Rho,following thesameprinciplesasdescribed for part I. Furthermore, to compare the staging of propensity to increase sunprotection between SEPI and RASP-B,the median scoreofSEPIpartIIwasassessedforeachofthethreestagesof
change(precontemplation,contemplationandactionstage)basedon whichwasthedominantstageaccordingtothesubjects’responses in RASP-B and statistical differences in response distribution betweenthestagestestedwithKruskall–Wallisanalysis. 2.4.Testingofreliability
2.4.1.Internalconsistency
InternalconsistencyofeachofthetwopartsofSEPIwastested byestimationofCronbach’salpha.ACronbach’salphacoefficient valueabove0.70wasinterpretedasanexpressionofgoodinternal consistency.
2.4.2.Stabilityovertime
Stability over time was assessed by a test-retest procedure, wherebytheparticipantsfilled-outtheSEPItwice;atbaselineand afterfourweeks.Correlationofindividualresponsesbetweenthe tworesponse occasionswas investigatedusingSpearman’s rho. Weusedthesamelevelsforcorrelationandstatisticalsignificance asdescribedforthevaliditytestingtointerpretagreement.
Thesameanalysesweremadeinallsubpopulations(student populationAustralia/Sweden, PHCpopulationAustralia/Sweden) aswellasintheoverallpopulations(Australia,Sweden).
2.5.ExploringdifferencesinSEPIoutcomebetweenAustraliaand Sweden
Differences in SEPI outcome between the Australian and Swedishtotalpopulationswereinvestigatedbymeansofmedian scores,for partI (0–32points)and partII(0–20points)of the instrument. Also, themedian scoresfor each of the individual questionsinbothpartswerecalculated.Statisticaldifferencesin median values were investigated using independent samples mediantest.
2.6.Ethicalapproval
In Australia, ethical approval was received by the ethical committee of QIMR Berghofer and QUT (QUT approval num-ber:1300000520/QueenslandInstituteofMedicalResearchHREC approvalnumber:P1539)andinSwedenbytheRegionalEthical ReviewBoardinLinköping(Dnr2013/146-13).
3.Results
3.1.Australiansamples
In the Australian PHC sample, 46 patients completed the questionnaires. Of these, one was excluded due to a missing writtenconsentform.Of theremaining45subjects,29 (64.4%) werefemaleand 16(35.6%)weremale.Theageswerebetween 26and 83withameanageof49years.TheAustralian student sample comprised 210 students who completed the question-naires.Ofthese,46 (22%)wereexcluded duetolackofcontact details,incompletequestionnaires,age<18yearsorlackofwritten consent.Oftheremaining164subjects70(42.7%)werefemaleand 93 (56.7%) were male. Genderinformation was missing in one subject(0.6%).Theagesrangedbetween18and50withameanage of21years.
3.2.Swedishsamples
IntheSwedishPHCsample76participantswererecruited.Of these, ten were excluded due to lack of contact details or incompletequestionnaires.Oftheremaining66participants,42 (63.6%)werefemaleand24(36.4%)weremale.Theagesranged
between30and 87 witha meanageof 64years.The Swedish studentsampleyielded132completedquestionnaires.Ofthese, ten were excluded due to lack of contact details, incomplete questionnairesorlackofconsent.Oftheremaining122subjects69 (56.6%)werefemaleand53(43.4%)weremale.Theagesranged between19and41withameanageof23years.
3.3.ValidityofSEPI
3.3.1.SEPIpartI
ThecorrelationbetweeneachseparatequestioninSEPIpartI andthecorrespondingquestionsintheSunprotectivebehaviour questionnaireisshowninTable1.Spearman’sRhowascalculated in all four subpopulations (student population in Australia/ Sweden,PHCpopulationinAustralia/Sweden) aswellasin the totalpopulationineachcountry(Australia,Sweden).Correlation coefficients showed satisfactory correlation for most of the questions, with the exception of the SEPI question concerning sun exposure on vacations, for which there was a negative correlation with sunscreen use during vacation. The highest coefficientvalueswereseenforIntentionaltanning,Occasionswith sunburnandHatorcapforsunprotection.
3.3.2.SEPIpartII
InTable2,thecorrelationbetweenthequestionsinSEPIpartII and the related questions in the Sun protective behaviour questionnaire, is displayed in the same manner as described
aboveforSEPIpartI.Table3showsthemedianscoresofSEPIpartII for each of the three stages of change (precontemplation, contemplationandactionstage), respectively, basedonwhich was thedominantstageaccordingtotheresponsesinRASP-B.Asseen in thetable, the medianSEPI score was generallylowerin the actionstagecomparedtothetwootherstages,whereastherewas no marked difference between the median scores in the contemplationandprecontemplationstages.
3.4.ReliabilityofSEPI
3.4.1.Internalconsistency
InTables4aand4b,theresultsoftheCronbach’salphaanalysis forassessmentofinternalconsistency,ispresented.ForSEPIpartI, theCronbach’s alphacoefficientin thetotalpopulations ofAus-traliaandSwedenwere0.69and0.61respectively.ForSEPIpartII, thecorrespondingoutcomeswere0.67 inAustraliaand 0.57 in Sweden.WithdeletionofthequestiononSunscreenuseinSEPIpart I, the Cronbach’s alpha increased to 0.71 in the Australian population,and0.73intheSwedishpopulation.
3.5.Teststability
3.5.1.Teststability
A test-retest analysed with Spearman’s Rho was also made betweenbothSEPIbymatchingtheanswersatbaselineandatone month’sfollow-up,inordertoevaluateteststabilityovertime.The
Table1
CorrelationbetweentheresponsestotheeightquestionsinSEPIpartIandtheoneormorerelatedquestionresponsesintheSun-protectivebehavioursquestionnaire(in italics),assessedwithSpearman’sRho.Asterisksindicatestatisticalsignificance(*=P<0.05,**=P<0.01).
Correlationcoefficient(Spearman’srho)
SEPIpartI—Questions Aus
stud. Aus PHC
Austot Swe stud.
Swe PHC
Swetot 1.Intentionaltanning
Howoftendoyousunbathewiththeintentiontogettanned?
Howoftendoyousunbathe? 0.76** 0.55** 0.73** 0.88** 0.83** 0.88**
2.Occasionswithsunburn
Howmanytimeshaveyoubeensunburnt(rednessandsmartingpain)duringthelast12months? Thinkaboutthetimefromlastsummeruntilnow.Howoftendidyougetthatsunburntthatwassoreortender thenextday?
0.70** 0.78** 0.75** 0.76** 0.68** 0.82** Thinkaboutthetimefromlastsummeruntilnow.Howoftenhaveyouhadsunburnthathasblistered? 0.35** 0.18 0.39** 0.09 0.38** 0.20** 3.Durationofstayinthesun
Howlongdoyouusuallystayinthesun(inaverage),between11amand3pm,onatypicalday-off?
Whenonholidays,howmuchtimedoyoutypicallyspendoutdoorsduring11am–2pm? 0.61** 0.63** 0.61** 0.44** 0.49** 0.42** 4.Vacationalsunexposure
Howoftendoyoutakeaholidaywiththeintentionofspendingmoretimeinthesun?
WhenIamonholidays,Iusesunscreenwhengoingoutdoors 0.01 0.51** 0.10 0.22* 0.22* 0.40** WhenIamonholidays,Ire-applysunscreenwhenoutdoors 0.03 0.21 0.13 0.22* 0.02 0.42** 5.Sunscreenuse
Wheninthesun,howoftendoyouusesunscreens?
WhenIamonholidays,Iusesunscreenwhengoingoutdoors 0.68** 0.64** 0.68** 0.54** 0.84** 0.67** WhenIamathome,Iusesunscreenwhengoingoutdoors 0.42** 0.72** 0.48** 0.48** 0.76** 0.58** WhenIamonholidays,Ire-applysunscreenwhenoutdoors 0.50** 0.53** 0.51** 0.54** 0.78** 0.64** WhenIamathome,Ire-applysunscreenwhenoutdoors 0.36** 0.40** 0.37** 0.43** 0.78** 0.54** 6.Clothesforsunprotection
Wheninthesun,howoftendoyouusecoveringclothesfor
Howoftenwouldyouwearclothescoveringmostofyourbody(includingarmsandlegs)toavoidthesun? 0.56** 0.66** 0.58** 0.67** 0.78** 0.74** Howoftenwouldyoudeliberatelywearlessclothingsoastogetsomesunonyourskin? 0.26** 0.24** 0.26** 0.31** 0.32** 0.36**
Coveringupwithclothes 0.57** 0.69** 0.62** 0.69** 0.64** 0.72**
7.Hatorcapforsunprotection
Wheninthesun,howoftendoyouuseasunhatorcapforsunprotection?
Howoftenwouldyouwearahat? 0.68** 0.53** 0.72** 0.76** 0.80** 0.78**
Wearingahatoutside 0.60** 0.46** 0.65** 0.65** 0.75** 0.71**
8.Stayingindoorsorintheshade
Howoftendoyoustayindoorsorintheshadeinordertoprotectyourselffromthesun?
Howoftenwouldyoustaymainlyintheshadetoavoidthesun? 0.52** 0.79** 0.59** 0.68** 0.70** 0.71** Howoftenwouldyouspendmostofthetimeinside? 0.46** 0.51** 0.49** 0.30** 0.54** 0.38**
Stayinginside 0.41** 0.57** 0.48** 0.37** 0.45** 0.38**
Stayingundershade 0.49** 0.58** 0.51** 0.64** 0.78** 0.71**
results are presented in Table 5, showing in general high correlationcoefficientvaluesforallquestions,inbothpartsofSEPI. 3.6.DifferencesinSEPIoutcomebetweenAustraliaandSweden
Table6comparessunexposurehabitsbetweentheAustralian andSwedishsamples,showingthemedianSEPIscoresforeachof thetwopartsoftheinstrument(partI:0–32points,partII:0– 20points).Overall,theSwedishsamplehadgenerallylowerlevels
ofsunprotectivebehaviours,andamarkedlylowerpropensityto increasesunprotectionthantheAustraliansample,illustratedby significantly higher total scores for both parts of the SEPI (p<0.001). Assessing individual items, it was notable that all itemsinSEPIpartIIassessingreadinesstoincreasesunprotection weresignificantlyhigherintheSwedishthanAustraliansamples. Similarly,allitemsinpartI(assessingcurrentsunexposurehabits) werehigherintheSwedishthanAustraliansamples,exceptfor OccasionswithsunburnandVacationalsunexposure,forwhichthe
Table2
CorrelationbetweentheresponsestothefivequestionitemsinSEPIpartII,addressingpropensitytoincreasesunprotection,andtheoneormorerelatedquestionresponses intheSun-protectivebehavioursquestionnaire(initalics),assessedwithSpearman’sRho.Asterisksindicatestatisticalsignificance(*=P<0.05,**=P<0.01).
Correlationcoefficient(Spearman’srho)
SEPIpartII—Questions Aus
stud Aus PHC
Austot Swe students
Swe PHC
Swetot Sunbathing
TheamountoftimeIspendinthesunisaproblemsometimes 0.17* 0.09 0.11 0.49 0.03* 0.04
Howoftendoyousunbathe? 0.68** 0.48** 0.66** 0.40** 0.63** 0.51**
Sunscreens
WhenIamathome,Iusesunscreenwhengoingoutdoors 0.43** 0.57** 0.47** 0.53** 0.79** 0.61** WhenIamonholidays,Ire-applysunscreenwhenoutdoors 0.42 0.50 0.44 0.61 0.72 0.65 WhenIamathome,Ire-applysunscreenwhenoutdoors 0.30 0.24 0.29 0.49 0.72 0.56 Coveringclothes
Howoftenwouldyouwearclothescoveringmostofyourbody(includingarmsandlegs)toavoidthesun? 0.59** 0.62** 0.60** 0.61** 0.65** 0.63** Howoftenwouldyoudeliberatelywearlessclothingsoastogetsomesunonyourskin? 0.25** 0.35* 0.28** 0.25** 0.12 0.24**
Coveringupwithclothes 0.60** 0.71** 0.64** 0.61** 0.50** 0.58**
Sunhatorcap
Wearingahatoutside 0.56** 0.53** 0.62** 0.58** 0.82** 0.68**
Howoftenwouldyouwearahat? 0.63** 0.51** 0.68** 0.62** 0.79** 0.71** Theshade
Howoftenwouldyoustaymainlyintheshadetoavoidthesun? 0.61** 0.51** 0.61** 0.61** 0.74** 0.68** Howoftenwouldyouspendmostofthetimeinside? 0.41** 0.29 0.42** 0.33** 0.48** 0.38**
Stayinginside 0.38** 0.33** 0.41** 0.29** 0.34** 0.29**
Stayingundershade 0.56** 0.49** 0.56** 0.58** 0.75** 0.65**
Keepingoutofthesunbetween11amand3pm 0.50** 0.56** 0.54** 0.47** 0.47** 0.49**
Table3
MedianscoreofSEPIpartIIforeachofthethreestagesofchange(precontemplation,contemplationandactionstage)basedontheresponsesinRASP-B. StageofchangeaccordingtoRASP-B SEPIpartIImedianscore SEPIpartIImedianscore
Australianpopulation Swedishpopulation
Students Patients Total Students Patients Total
Precontemplationstage 6 4 5 12 11 11
Contemplationstage 7 3 6 12 12 12
Actionstage 4 1.5 3 7 8 7
Sign.(Kruskall–Wallis) 0.11 0.32 0.009 0.048 0.33 0.01
Table4a
InternalconsistencyofSEPIpartI,intermsofCronbach'salpha,displayedforthefullscore,andwithdeletionofeachoftheingoingquestions. Australianpopulation Swedishpopulation (Cronbach’salpha) (Cronbach’salpha)
Students Patients Total Students Patients Total
ValueforSEPIasawhole 0.66 0.43 0.69 0.63 0.50 0.61
Valueafterdeletionofsinglequestions,asfollows:
1.Intentionaltanning 0.62 0.41 0.65 0.53 0.39 0.50
2.Occasionswithsunburn 0.63 0.43 0.66 0.62 0.47 0.57
3.Durationofstayinthesun 0.61 0.37 0.64 0.55 0.41 0.54
4.Vacationalsunexposure 0.61 0.50 0.65 0.62 0.48 0.59
5.Sunscreenuse 0.67 0.53 0.71 0.69 0.65 0.73
6.Clothesforsunprotection 0.64 0.29 0.67 0.58 0.39 0.54
7.Hatorcapforsunprotection 0.67 0.29 0.67 0.63 0.48 0.60
Table4b
InternalconsistencyofSEPIpartI,intermsofCronbach’salpha,displayedforthefullscore,andwithdeletionofeachoftheingoingquestions. Australianpopulation Swedishpopulation (Cronbach’salpha) (Cronbach’salpha)
Students Patients Total Students Patients Total
ValueforSEPIasawhole 0.67 0.55 0.67 0.60 0.59 0.57
Valueafterdeletionofsinglequestions,asfollows:
1.Intentionaltanning 0.65 0.43 0.64 0.62 0.51 0.53
2.Sunscreenuse 0.62 0.62 0.65 0.64 0.70 0.68
3.Clothesforsunprotection 0.61 0.47 0.62 0.46 0.37 0.38
4.Hatorcapforsunprotection 0.62 0.56 0.63 0.56 0.55 0.52
5.Seekingtheshade 0.57 0.34 0.57 0.43 0.46 0.40
Table5
StabilityovertimeoftheSEPI,expressesascorrelationbetweenthesubjects'responsesatbaselineandafteronemonth,assessedwithSpearman'sRho.Asterisksindicate statisticalsignificance(*=P<0.05,**=P<0.01).
Correlationcoefficient(Spearman'sRho)
SEPIPartI—Questions Ausstud AusPHC Austot Swestud SwePHC Swetot
Intentionaltanning 0.84** 0.65** 0.83** 0.84** 0.79** 0.83**
Occasionswithsunburn 0.68** 0.88** 0.79** 0.57** 0.65** 0.75**
Durationofstayinthesun 0.80** 0.56** 0.74** 0.58** 0.67** 0.64**
Vacationalsunexposure 0.69** 0.42** 0.68** 0.91** 0.84** 0.89**
Sunscreenuse 0.70** 0.80** 0.74** 0.74** 0.74** 0.74**
Clothesforsunprotection 0.61** 0.72** 0.64** 0.71** 0.72** 0.75**
Hatorcapforsunprotection 0.59** 0.74** 0.73** 0.61** 0.70** 0.67** Stayingindoorsorintheshade 0.63** 0.52** 0.63** 0.63** 0.69** 0.69** SEPIPartII—Questions
Sunbathing 0.84** 0.69** 0.82** 0.65** 0.83** 0.76**
Sunscreens 0.40** 0.93** 0.57** 0.83** 0.86** 0.87**
Coveringclothes 0.75** 0.88** 0.80** 0.66** 0.70** 0.69**
Sunhatorcap 0.69** 0.27 0.72** 0.59** 0.81** 0.72**
Theshade 0.68** 0.68** 0.68** 0.79** 0.65** 0.71**
Sunbathing 0.84** 0.69** 0.82** 0.65** 0.83** 0.76**
Table6
ComparisoninSEPIoutcomebetweentheAustralianandSwedishtotalpopulations,expressedasmedian scores,alsoshowingthesubscoreforeachoftheindividualquestionsincluded.Statisticalsignificancevalues refertodifferencesinmedianscorebetweenthetwopopulationsassessedwithindependentsamplesmedian test.
Medianscore
SEPIPartI—Questions Australianpopulation Swedishpopulation Sign. (Mediantest)
Intentionaltanning 0 2 <0.001
Occasionswithsunburn 1 1 0.03
Durationofstayinthesun 1 2 <0.001
Vacationalsunexposure 1 1 0.003
Sunscreenuse 1 1 0.081
Clothesforsunprotection 2 3 <0.001
Hatorcapforsunprotection 2 3 <0.001 Stayingindoorsorintheshade 2 2 <0.001
Totalscore 11 14 <0.001
SEPIPartII—Questions
Sunbathing 0 3 <0.001
Sunscreens 0 1 <0.001
Coveringclothes 1 3 <0.001
Sunhatorcap 1 3 <0.001
Theshade 1 2 <0.001
Australiansamplescoredhigher,andSunscreenuse,forwhichthe differenceinresponsedistributionwasnotstatisticallysignificant. 4.Discussion
The Sun Exposure and Protection Index (SEPI) is a novel instrumentforgradingsunexposurehabits,intendedtobeusable bothasaplatformtocommunicatetailoredsunprotectionadvice onanindividuallevel,andtomeasuresunexposureandprotection on a group level, e.g. as a tool to evaluate the effect of an intervention.Inthisstudy,theSEPIwasshowntobestableand reproducible, and to have in general acceptable validity when comparedwiththequestionsinthesomewhatmoreextensivesun protective behaviourquestionnaire of RASP-B. Overall, internal consistencybetweentheitemswasalsoshowntobeacceptable. ThelevelofcorrelationbetweentheseparatequestionsinSEPI andthecontrolquestionsvaried,asshowninTable1and2.The reasons behind the occasions of lower correlation values are probablyvarious.Forexample,thecorrelationbetween“Howmany timeshaveyoubeensunburnt(rednessandsmartingpain)duringthe last12months?”and“Thinkaboutthetimefromlastsummeruntil now.Howoften haveyou hadsunburnthat hasblistered?”might dependonthefactthatblistersdeveloplessfrequentlythantypical sunburn.Furthermore,inSwedenblistersprobablydevelopless commonlythaninAustraliaduetothegenerallylessintenseUV radiation.Inthecaseofsunscreenuse,theSEPIquestioncorrelated bestwiththequestionsaddressingvacationalapplication,andless witheverydayusewhenathome,possiblyreflectingdifferencesin risk perception between the two samples associated with “at home”UV-exposure.
InternalconsistencyreflectedbyCronbach’salphaturnedoutto beslightlylowerthanthedesired>0.70coefficientvaluegenerally recommended. In part, this was probably due to the limited numberofquestions,andrelativelysmallstudysamples.Perhaps more importantly, we found that the questions concerning sunscreenuseweretheleastconsistentinternallyandthat, for bothpartsIandII,deletionofthesewouldincreasethevalueofthe Cronbach’salphacoefficient considerably (inpart I >0.70).The mainreason behind this is probablythesunscreenparadox, as mentionedearlier[18,19],sincepeoplewhoareusingsunscreens alsoaretheonesspending moretimeinthesun,makingthese specific questions operatein opposite directions. Although the resultsmight indicate that the sunscreen questions should be excludedfromthescore,thiswould,however,belessbeneficialfor identifying those individuals with the highest risk behaviour (individuals with intense sun exposure and rarely using sunscreens). Thus, with regard to the sunscreen paradox, the usefulness of the SEPI is likely to be assisted by leaving the questionsinplace.
As might beexpected, themedian scoreof SEPI partII was generallylowerin theaction stagecompared tothe twoother stages,reflectinga higherpropensitytoincreasesunprotection, whereastherewasnodifferencebetweenthemedianscoresinthe precontemplationand contemplationstages.The reasonforthe lattermight be the basicdifference betweenSEPI and RASP-B, namelySEPI assessing readiness to increase sunprotection (or reduce sun exposure) within different behavioural aspects (seekingtheshade,usingsunscreensetc),resultinginacumulated score,whileallquestionsinRASP-Barerestrictedtothegeneral aspectof“spendinglesstimeinthesun”,resultinginadominant stageinsteadofascore.ThismakesRASP-Basomewhatcoarser instrument.
A possibly expected finding was that the Swedish samples showed a significantly higher level of sun seeking behaviour, coupled with a lower propensity to increase sun protection, comparedwiththeAustraliansamples.Thiswastrueforallitems
except for measures of sunburn and vacational sun exposure, whichwerehigherforAustraliansubjects.Thismostlikelyreflects anaturalconsequenceofthemarkedlysunnierAustralianclimate. Itmightalsoreflect,inpart,thatthequestiononvacationalsun exposurebyintentiondifferedsomewhatincontentbetweenthe two UVR environments. With this exception, the remaining questions did not differ betweenthe two language versions,a circumstancethatmaybediscussed.Forexample,inAustraliaa broadbrimmedhatisthegenerallyrecommendedprotectionfor thefaceandhead,whereasinSwedenthisisaveryuncommon headdress,a reason forchoosing themore neutralterminology “sunhatorcap”inthescore.Althoughtheterm“sunhat”aimsto includeawiderrangeofalternatesunprotectiveheadwear,suchas bucketorlegionnaireshats,futurerevisionsoftheinstrumentmay benefitfromspecifyingthesetypesofheadwearinthequestion.In doingso,theywouldcapturethosetypesofheadwearthatoffer thegreatestprotectiontotheface,neckandears,asopposedto “cap”,fromwhichthesunprotectiveeffectinmanycasesislikely tobeinsufficient.Despiteaninevitableelementoflanguageand environmentaldisparitiesinthepresentversion,asawholethe SEPIappearstobeusefulinexploringdifferencesinindividuals overtime,betweengroupsofindividualsorbetweenpopulations. Although the number of study participants was lowerthan originallyintended,especiallyinthetwoPHCsamples,thefactthat thestudy was performedin two highlydifferentUVR environ-mentsrepresentsanimportantstrengthofthestudy,theresults indicating that theSEPI instrument canreliablybe usedin the populationsofbothenvironments.Moreover,thedifferentstudy subpopulationscoverabroadagespectra,albeitwithasomewhat moresparserepresentationinlowermiddleage.Thelowerthan intendednumberofparticipants,mainlyinthePHC subpopula-tions,wasmostlyduetolimitationofthetimeframesofthestudy, andthattherecruitmentofPHCpatientstooksomewhatlonger than expected. Also, difference in the recruitment procedure betweenthestudentandPHCsamplesislikelytohavecontributed to the lower sample size achieved in the two PHC samples, students receiving a short oral information presentation in connectionwithalecture,whereasthePHCpatientsonlyreceived a writteninformation at registrationin thereception.Ideally,a more active recruitment strategy, incorporating both oral and written information may have been beneficial for this group. Unfortunately, for practical reasons, extending the recruitment periodwasnotpossible.Anadditionalstudylimitationisthatthe seasonsforfilling-outthequestionnairesdifferedbetweenthetwo countries.TheAustralianpopulationfilled-outthequestionnaires in their spring whereas the Swedish population filled-out the questionnairesduring theautumn. Thiscouldhaveaffectedthe resultsbymeansofpossiblerecallbias;ideally,anadditional half-yearfollow-uporwouldpotentiallyhaveovercomethislimitation. However,thewinterclimateinBrisbaneissimilartothesummer climateinSweden,bymeansofambientUVradiation[31,32],and in contrary toSweden there is anall-year-round need for sun protection,alsointhewinter.Thismayhavebeencontributoryin diminishingthisdisparity.
Besidesageandgender,nootherdemographicpropertieswere askedforfromtheparticipants.Otherfactorsknowntodetermine sun exposure habits include ethnicity, skin colour and self-perceived UV skin sensitivity. However, no mapping of these factorswasmadeinthepresentstudy,butremainstobeexplored infuturestudiesaddressingtheapplicabilityofSEPIindifferent settings and with regard to varying responder characteristics. Finally,wehadnoinformationaboutnon-responders,and soit remainspossiblethatoursurveyisbiasedduetoself-selectionof participants.
AnadvantageoftheSEPIisthatitisshortandquicktocomplete whichincreasesitsattractivenessforclinicaluse.Inpractice,SEPI
takesonlyafewminutestocomplete,andcouldeasilybefilled-out prior to the doctor's visit. Although this shortness entails a subsequentlackofdetailedinformation,theinformationlossfrom low response rates commonly associated with extensive ques-tionnairesshouldnotbeunderestimated.Also,thecombinationof thetwopartsofSEPI,addressingnotonlythepresentbehaviour butalsothepropensitytochangeit,inthesameinstrument,gives theuseracomprehensivepictureofwhethertheresponderneeds toincreasesunprotection,aswellasthelikelihoodtosuccessfully promotesuchachange.Finally,thepossibilitytolookatSEPIboth asaglobalscoreortofocusonindividualquestions/behaviours may be useful for constructive risk communication, a clear advantageincomparisonwithpreviousinstruments[22,23,27].
Inconclusion,theSEPIappearstobeastableinstrumentwith overall acceptable validity and reliability, and is applicable to evaluateindividual sunexposureand protection inpopulations exposedtodifferentUVRenvironments.Thequestiononsunscreen useaffectedinternalconsistencysomewhatnegatively,butthere are reasonable grounds for retaining this item. With its short formatSEPIislikelytobeeasilyusedinclinicalpracticeandcould contributetohigher response frequencies insurveys. This new instrumentconstitutesausefulandnovelcontributiontothefield ofskincancerprevention.Forfuturestudies,replicationinalarger population would be desirable, and possibly also in different populations or settings, as well as translation into additional languages.
Conflictsofinterest None.
Authorcontribution
Hedvig Detert: Data collection and analysis, manuscript writing.
SaraHedlund:Datacollectionandanalysis,manuscriptwriting. ChrisAnderson:Projectplanning,developmentofSEPI instru-ment,manuscriptwriting,expertiseindermatology/skincancer.
Ylva Rodvall: Development of SEPI instrument, manuscript writing,expertiseinskincancerpreventionandpublichealth.
KarinFestin:Statisticalexpertise/analyses,alsocontributingto there-writingoftherevisedversionofthemanuscript.
DavidWhiteman:ProjectmanagementinAustralia, develop-ment of SEPI instrument, manuscript writing, expertise in epidemiologyandpreventionofskincancer.
MagnusFalk:Projectplanning,dataanalysis,developmentof SEPIinstrument,manuscriptwriting,projectmanager,expertisein generalpracticeandskincancerprevention.
Acknowledgement
ThestudywasfinancedbytheCountyCouncilofÖstergötland, Sweden.
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