Electronic Continuous Pain Measurement vs Verbal Rating Scale in gynaecology: A prospective cohort study

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University of Groningen

Electronic Continuous Pain Measurement vs Verbal Rating Scale in gynaecology

Louwerse, Marjoleine D; Hehenkamp, Wouter J K; van Kesteren, Paul J M; Lissenberg, Birgit

I; Brölmann, Hans A M; Huirne, Judith A F

Published in:

European Journal of Obstetrics, Gynecology, and Reproductive Biology

DOI:

10.1016/j.ejogrb.2020.11.012

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Louwerse, M. D., Hehenkamp, W. J. K., van Kesteren, P. J. M., Lissenberg, B. I., Brölmann, H. A. M., &

Huirne, J. A. F. (2021). Electronic Continuous Pain Measurement vs Verbal Rating Scale in gynaecology: A

prospective cohort study. European Journal of Obstetrics, Gynecology, and Reproductive Biology, 256,

263-269. https://doi.org/10.1016/j.ejogrb.2020.11.012

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Electronic

Continuous

Pain

Measurement

vs

Verbal

Rating

Scale

in

gynaecology:

A

prospective

cohort

study

Marjoleine

D. Louwerse

a,

*

,

Wouter

J.K.

Hehenkamp

a

,

Paul

J.M.

van

Kesteren

b

,

Birgit

I. Lissenberg

c

,

Hans

A.M.

Brölmann

a

,

Judith

A.F.

Huirne

a

a_Department_of_Obstetrics_and_Gynaecology,_Amsterdam_University_Medical_Centres,_Amsterdam,_the_Netherlands b

DepartmentofObstetricsandGynaecology,OLVGEast,Amsterdam,theNetherlands

c

DepartmentofEpidemiologyandDataScience,AmsterdamUniversityMedicalCentres,Amsterdam,theNetherlands

ARTICLE INFO

Articlehistory:

Received5February2020

Receivedinrevisedform27October2020 Accepted6November2020

Keywords: Pain

ContinuousPainScoreMeter

Continuousreal-timepainmeasurement Electronicpainmeasurement

VerbalRatingScale VisualAnalogueScale Outpatienthysteroscopy Colposcopy

Ovumpick-up

ABSTRACT

Objective:Tocomparepainmeasuredwithanewelectronicdevice–theContinuousPainScoreMeter (CPSM)–andtheVerbalRatingScale(VRS)duringgynaecologicalproceduresinanoutpatientsetting, andtocorrelatetheseoutcomeswithbaselineanxietyandpatient(in)tolerancetotheprocedure. Studydesign:Thisprospectivecohortstudywasundertakenintwocentres:auniversityhospitalanda largeteachinghospitalinTheNetherlands.Patientsundergoinganoutpatienthysteroscopy,colposcopy orovumpick-upprocedureforin-vitro fertilizationin oneofthetwoparticipating hospitals with availabilityoftheCPSM wereincluded.PainwasmeasuredbyboththeCPSMandtheVRS.Patient tolerancetotheprocedurewasreported.VariousoutcomesoftheCPSMwerecomparedwiththoseofthe VRSandrelatedtobaselineanxietyscores.

Results:Ninety-oneof108includedpatients(84%)usedtheCPSMcorrectlyduringtheprocedure,andit waspossibletoanalysetheCPSMscoresfor87women(81%).TheCPSMscoreswerealllinearlyrelatedto theVRS.ThepeakpainscoreontheCPSM(CPSM-PPS)hadthestrongestcorrelationwiththeVRSscore forallthreeprocedures.HigherCPSM-PPSwasrelatedtopatient(in)tolerancetotheprocedure(p=0.03– 0.002).Anxietyatbaselinewasnotcorrelatedwithpainperception,exceptforVRSduringcolposcopy(r= 0.39,p=0.016).

Conclusion:ThemajorityofpatientswereabletousetheCPSMcorrectly,resultingindetailedinformation onpainperceptionforeachindividualpainstimulusduringthreeoutpatientgynaecologicalprocedures. The CPSM-PPS had the strongest correlation withthe VRS score and patient (in)tolerance to the procedure.

Introduction

Minimally invasive surgery has evolved in all surgical dis-ciplines.Moreandmoregynaecologicalproceduresareperformed inanoutpatientsettinggiventhehealthandeconomicbeneﬁtsof theseminimallyinvasiveprocedures[1–3].Forexample, diagnos-ticandtherapeutichysteroscopiesareperformedincreasinglyin outpatientsettings[4–7].Patientperceptionsofpainexperienced duringaprocedureplayakeyroleintheirperceivedtoleranceand theirsatisfactionconcerningthetreatment[8–12].However,pain perception can differ widely between patients and could be aggravated by anxiety [13_–15], underlining the need for pain

measurement and assessment of patient tolerability [16,17]. Obtainingdetailedinformationonpainperceptionduringdifferent partsofaprocedureenablesadjustmentsthataimtoreducepain andimproveperceivedtoleranceandthesuccessrateofspeciﬁc interventions.

Ingeneral,painintensityismeasuredafteraprocedureusing theVisualAnalogueScale(VAS)ortheVerbalRatingScale(VRS) [18].Thesescoresareobtainedwiththeuseofan11-pointscale indicating_‘nopain_’to_‘worstimaginablepain_’.Althoughquickand easytoperform,thesemethodshavetheirlimitations:inabilityto measure pain of different pain stimuli during a procedure, inaccuracy ofmemory torecall thesensationof pain, and lack ofinformationonthepossiblerelationshipbetweenpaintolerance and lengthof procedure.To overcome theselimitations, a new instrumenthasbeendeveloped–thevalidatedContinuousPain ScoreMeter(CPSM).Thismeasurespaincontinuously,generating an ‘experienced pain curve’ obtained during all steps of an

*Correspondingauthorat:UMCG,Centerforreproductivemedicine,HPCCB35, Postbus30.001,9700RB,Groningen,theNetherlands.

E-mailaddress:mail@marjoleinelouwerse.nl(M.D.Louwerse).

ContentslistsavailableatScienceDirect

European

Journal

of

Obstetrics

&

Gynecology

and

Reproductive

Biology

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intervention [19]. Previous studies have demonstrated the feasibilityofelectronicpainmeasurementandpatientspreferred this to pain evaluation on paper [20–23]. To the authors’ knowledge, use of the CPSM during gynaecological procedures hasnotbeenevaluatedpreviously.

Theaimofthisstudywastodeterminethefeasibilityofthe CPSMduringthreedifferentgynaecologicaloutpatientprocedures, andtocomparetheoutcomeswithreportedVRSscores,patient perceivedtoleranceandbaselineanxietyscores.

Materialsandmethods Studydesignandparticipants

ThisprospectivecohortstudywasconductedbetweenAugust andNovember2011attheoutpatientclinicsoftheDepartmentof GynaecologyoftheOnzeLieveVrouweGasthuis(OLVG)andthe VUmedicalcentre(VUmc)inAmsterdam,TheNetherlands.

Eligible patientswere askedfor informedconsent. Inclusion criteria were: age 18–80 years; and scheduled to undergo colposcopy,ovumpick-uporhysteroscopyinanoutpatientsetting. Exclusioncriteriawere:inabilitytocomprehendDutchorEnglish properly;and(forhysteroscopy)pregnancyorbeingintheluteal phasewithouttheuseofcontraception;knowncervicalstenosisor malignancy; current sexually transmitted disease or pelvic inﬂammatorydisease;or contra-indicationsfortheuseof non-steroidalanti-inﬂammatorydrugs(NSAIDs).

All gynaecological procedures were performed under stan-dardized conditions. In all hysteroscopy cases, a 5.5-mm rigid scope with a 30 optical angle was used (Olympus Europe, Hamburg,GermanyatOLVG;Storz,Tüttlingen,GermanyatVUmc). Operatingsheathswere5Frand7Fr,respectively.Patientswere instructedtotakeNSAIDs(500mgNaprosyne)theeveningbefore and 2–3 hbeforehysteroscopy. Local anaesthesia in thecervix (cervicalblock),acombinationofArticainandadrenaline(3.4ml UltracainD-Sforte,40mg–5

m

g/mL,Sanoﬁ-Aventis,Paris,France), was givenonlyifcervicaldilatationwasperformed.During this procedure, small intracavitary abnormalities were removed if detected.CuscospeculaandanOlympusOCS500colposcopewere usedinallcolposcopypatients;noneofthemreceivedanaesthetic. Ovumpick-upprocedureswereachievedusinga1.4-mm(17GA, Repromed)needlewithalengthof35cm.Inadvanceofthe pick-up, all women received opioids (2 ml pethidine, 50 mg/mL, Martindale Pharmaceuticals, London, UK) and benzodiazepines (7.5mgDormicuminwomenweighing<70kgor15mgDormicum

inwomenweighing>70kg,AllianceHealthcare,Chessington,UK). Applied medication and eventual co-interventions were regis-tered.

ContinuousPainScoreMeterandpainsoftware

TheCPSMwasdevelopedin2008andvalidationfollowedin 2009measuringreproduciblepainstimuliinhealthyvolunteers [19].Anadjustablesliderwhichisavoltagedivider(Studiofader 100KB,AlpsElectricCo.,Ltd,Tokyo,Japan)isattachedtothemeter, a30-cmbox,tomarkpainintensityonacontinuousscalebasedon theVASfrom0to10(Fig.1).Whenapatientreleasesthisslider,it willreturntoitsoriginalposition,therebypreventingerroneous highmeasurement. TheCPSM isconnected toa computerthat containsspecialdevelopedpainsoftware(PainScope).Itmeasures anddocuments,throughthe(changing)positionoftheslider,10 painstimulipersecondandtransformstheimportedinformation in a graph (Fig. 2). Obtained data are translated into three outcomes:theareaunderthecurve(CPSM-AUC),thepeakpain score(CPSM-PPS, thehighest registeredscore) andthe average painpersecond(CPSM-APS,thetotalCPSM-AUCdividedbythe totaloperationtime).Duringpainmeasurement,theexamineris abletomarkthebeginningandendofspeciﬁcpartsofaprocedure (e.g.placementofaspeculum,startandendofcervicaldilatation, scopepassagethroughtheendocervix,orstartandendofapolyp resection).Thesemarkerswillbedepictedinthepaingraph,which makesitpossibletoevaluatethepainoutcomesofthesespeciﬁc parts of theintervention. Allthesedata areprocessed for data managementandstatisticalanalysesusingExcel(MicrosoftCorp., Redmond, WA, USA) and SPSS (IBM Corp., Armonk, NY, USA) software.

Datacollection

First, baseline characteristics and patients’ anxiety scores (Likert scale: 0 = no anxiety to 10=extremely anxious) were registered. When the patient was positioned, she received instructionsontheuseoftheCPSM;asapartofthisinstruction, theCPSMwastestedonce beforethestart oftheprocedure by givingthepatientamildpressurestimulusonherhand.Women wereaskedtoexpresstheirpainbycontrollingtheCPSMduring theentireprocedure.Whentheexaminersuspectedincorrectuse ornousageatall,patientswereremindedofthepresenceofthe CPSMandgentlyaskedtouseit.Thedegreeof(in)correctusage accordingtotheinvestigatorandpatient,usingan11-pointscale

Fig.1.TheContinuousPainScoreMeter:laptopwiththesoftware(PainScope)andthepainslider.

M.D.Louwerse,W.J.K.Hehenkamp,P.J.M.vanKesterenetal. EuropeanJournalofObstetrics&GynecologyandReproductiveBiology256(2021)263–269

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(0=alwayscorrectto10=alwaysincorrect),wasregisteredinthe casereportform.Painmeasurementswereexcludedfromanalysis whentheinvestigator,patientorbothscored5(i.e.incorrectuse) onthisscale.Variousstandardizedmarkers(e.g.forhysteroscopy, two of the 12 registered markers are passing external os and passing internal os) were placed in the pain score graph electronically bytheexaminerduringtheprocedureinorderto enable laterdifferentiationbetweenvariouspartsof the proce-dure,astheymayserveasdifferentpainstimuli(Fig.2).

Immediately after the procedure, participants were asked to expresstheaveragepainexperiencedduringtheentireprocedure usingtheVRS.Also,thepatient’sperceptiononhowtheytoleratedthe procedure was registered (tolerated yes/no, willingness to undergo the procedureagainifneededandtheirrecommendationtoafriend). Statisticalanalysis

SPSSVersion25forWindowswasusedafterimportingthedata from an Exceldata sheet.To correlatethe newpain units and baseline anxietywith theVRS score, Pearson’s correlation was calculatedwith95%conﬁdenceintervals[24].Two-sidedp-values werereported.Aprobabilitylevelof<0.05wasusedforstatistical signiﬁcance.

The Mann–WhitneyU-testwas usedtocomparemediansof non-normally-distributedpainscoresandtodifferentiatebetween tolerabilityandintolerabilityofaprocedure.Whenresultswere normally distributed, calculations were executed using the independentsamplest-test.Boxplotsvisualizedpatienttolerance ofhysteroscopicprocedurescomparedwithpainscores.Stata/IC Version11.2wasusedtocreatereceiveroperatingcharacteristic (ROC)curvestoreportpatienttolerancefornon-normal distribu-tionsinordertocompareCPSMscoreswithVRSscores.

Apost-hocpoweranalysiswasperformedtoconﬁrmadequate power and thereby ensure the signiﬁcance of the results. The primaryobjectiveofthisstudywastodeterminethecorrelation betweenresultsoftwodifferentmeasurementinstruments:the

VAS and the CPSM (CPSM-AUC, CPSM-PPS, CPSM-APS). The

analysiswasbasedoncorrelationsof0.80,0.82and0.39(Table3). Results

Of the women who met the selection criteria,108 women agreed to participate in this study. Baselinecharacteristics are describedinTable1.

Colposcopy

Allpainmeasurementswerecompletedforthe51patientsin thisgroup.In12cases,theinvestigator(n=3),thepatient(n=5)or both(n=4)judgedtheusageoftheCPSMtobeincorrect.Inthis subgroup,meanexperiencedpain(VRS)wasequaltoandanxiety washighercomparedwiththegroupwhousedtheCPSMcorrectly (p=0.088andp=0.005,respectively)(Table2).Theresultsforthe remaining39women(76%)wereanalysed.

Table 2 shows the results of the pain measurements and tolerability during colposcopy. All CPMSoutcomes (CPSM-AUC, CPSM-PPS and CPSM-APS) were linearly related to the VRS

Fig.2.Exampleofapainscoregraphduringhysteroscopy.Differentstandardizedmarkers(i.e.startand/orendofspeciﬁcprocedures)aredepictedinthegraphwhilethe proceduretookplace.

Table1

Baselinecharacteristicsoftheparticipants. Procedure Patientvariables Colposcopy

(n=51)

Ovumpick-up (n=27)

Hysteroscopy (n=30) Age(years),meanSD 34.69.3 36.04.3 45.813.9 BMI(kg/m2 ),meanSD 21.52.5 23.53.2 25.24.5 Smoking,n(%) Yes 19(37.2) 2(7.4) 4(13.3) No 29(56.9) 25(92.6) 24(80.0) Unknown 3(5.9) 0(0.0) 2(6.7) Contraceptiveuse,n(%) None 18(35.3) 27(100.0) 22(73.3) Hormonal 23(45.2) 0(0.0) 3(10.0) Condom 2(3.9) 0(0.0) 5(16.7) Other 8(15.6) 0(0.0) 0(0.0) Parity,median(IQR) 0.0(2.0) 0.0(1.0) 1.0(2.0)

Caesareandelivery 0 0.0(0.0) 0.0(0.0) Nulliparous,n(%) 33(64.7) 19(70.0) 9(30.0) Menopausalstate,n(%)

Premenopausal 50(98.0) 27(100.0) 21(70.0) Postmenopausal 1(2.0) 0(0.0) 9(30.0) Surgicalprocedureinhistory,n(%)

Cervix 4(7.8) 1(3.7) 0(0.0) Uterus 3(5.9) 2(7.4) 5(16.6) Tubes 0(0.0) 4(0.15) 2(6.6) Indicationfortheprocedure,n(%)

AUB 0(0.0) 0(0.0) 24(80.0)

Infertility 0(0.0) 27(100.0) 2(6.7) Abnormalcervixcytology 42(82.4) 0(0.0) 0(0.0) Postcoitalbleeding 9(17.6) 0(0.0) 0(0.0) Other 0(0.0) 0(0.0) 4(13.3) BMI,bodymassindex;SD,standard deviation;IQR,interquartilerange; AUB, abnormaluterinebleeding.

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(p=0.001)(Table3).TheCPSM-PPSshowedthestrongest‘almost perfect’correlation (r= 0.86); for both theCPMS-AUC and the CPSM-APS,thecorrelationcoefﬁcientwas0.82.

Allwomenexcepttworeportedthatcolposcopywastolerable without additional anaesthesia. The mean VRS score in the ‘tolerable’groupwas2.8[standarddeviation(SD)2.4]compared with5.0(SD2.8)inthe_{‘intolerable’}group.ThemedianCPSM scoresforthe‘tolerable’vs‘intolerable’groupswere:CPSM-AUC 311.8[interquartilerange(IQR)1907.6]vs3749.0(IQR-);CPSM-PPS 1.9(IQR5.3)vs10.0(IQR-);andCPSM-AP:1.5(IQR4.2)vs7.3(IQR -)].ThedifferencewassigniﬁcantforCPSM-PPS(p=0.03).

Anxiety at baseline showed signiﬁcant ‘fair’ correlation (r= 0.39)withtheVRSscore(p=0.016),butnotwithanyoftheCPSM scores.

Ovumpick-upprocedure

Ofthe27womenintheovumpick-upgroup,CPSM measure-mentscouldbeincludedfor21(78%)womenforstatisticalpain analysis.Therewassoftwarefailureintwocases,andfourpatients scored5indicatingincorrectuseoftheCPSM.Meanexperienced painscore(4.7)andmeanbaselineanxietyscore(1.7)wereequal comparedwithwomenwhousedtheCPSMcorrectly(p=0.87and p=0.088,respectively)(Table2).

Painscoresduringovumpick-uparereportedinTable2.VRS scores were‘substantially’ correlated with CPSM-PPS (r= 0.80,

p=0.001)and‘moderately’correlatedwithCPSM-APS(r=0.55,p= 0.009),butwerenotcorrelatedwithCPSM-AUC(seeTable3).

One-thirdofthewomenreportedthattheyexperiencedovum pick-up under the current conditions asintolerable due to the perceived pain (n = 7). Pain scores were signiﬁcantly higher compared with women who reported that the procedure was tolerable(n=14);meanVRSscore7.0(SD2.2)vs3.3(SD2.3)(p =0.007);medianCPSM-AUC4681.5(IQR12204.3)vs591.3(IQR 3620.8)(p=0.009);medianCPSM-PPS9.2(IQR3.3)vs2.9(IQR3.1) (p=0.002);andmedianCPSM-APS12.8(IQR23.7)vs1.5(IQR8.7) (p=0.007),respectively.

AnxietyscoreatbaselinewasnotcorrelatedwiththeVRSscore oranyoftheCPSMscores(p0.49).

Outpatienthysteroscopy

Intotal,30patientswereincludedinthehysteroscopygroup; theCPSMoutcomes couldbeanalysedfor 27 of thesepatients (90%).Inonecase,theCPSMfailedbecauseofsoftwareproblems; inanothercase,hysteroscopyfailedduetocervicalstenosis;andin thethirdcase,thepatientforgottoadjusttheCPSMsliderduring theprocedure.The reportedmeanVRS score(7.0) andbaseline anxietyscore(1.0)weresimilarinthegroupwithevaluableCPSM outcomesandthegroupwithnon-evaluableoutcomes(p=0.34 andp=0.21,respectively)(Table2).

Painscores,anxietyscores,tolerabilityandtotaloperationtime arereportedinTable2.VRSscoreswerelinearlyrelatedtoallofthe CPSMoutcomes(Table3).CPSM-PPSwas‘substantially’(r=0.77) related(p=0.0001),CPSM-AUCwas‘moderately’(r=0.43)related (p=0.025)andCPSM-APSwas‘fairly’(r=0.39)related(p=0.042). ReportedVRSscoresweresigniﬁcantlylowerinthegroupof patientswhoreportedthattheproceduresweretolerable(n=22) underthecurrentconditionscomparedwiththosewhoreported thattheprocedureswereintolerable(n=5)(Fig.3).ThemeanVRS scorewas3.1(SD2.3)vs7.2(SD2.6),respectively(p=0.007). MedianCPSM-PPSwas2.5(IQR3.0)and10.0(IQR6.0),respectively (p=0.014).DifferencesinmedianCPSM-AUCandCPSM-APSwere not signiﬁcant: CPSM-AUC 1173.5 (IQR 2903.4) vs 2470.0 (IQR 5094.8)(p=0.26)andCPSM-APS3.5(IQR6.89)vs5.5(IQR4.56)(p =0.26).Thedegreeofanxietyatbaselinewasnotrelatedtoanyof thereportedpainoutcomesduringhysteroscopy(p0.59).

The pain scores of the different parts of the hysteroscopic procedures are reportedin Table 4. The fourevents that were

Table2

Outcomemeasuresconcerningpainduringandaftertheprocedure;anxietyscoreatbaseline;totalproceduretime;andoverallpatienttoleranceofcolposcopy,ovumpick-up andhysteroscopy. Procedure Measurementvariablesa Colposcopy (n=39) Ovumpick-up (n=21) Hysteroscopy (n=27) VRS+CPSMb 2.82.3 4.52.8 4.12.9 VRS–CPSMc 4.22.6 4.70.6 7.0 CPSM-AUC 496.0(1971.4) 2610.9(6414.7) 1175.8(4263.3) CPSM-PPS(VASmax) 1.8(5.5) 3.6(5.5) 2.9(4.7) CPSM-APS(Tauc/Ttime) 1.5(4.4) 8.0(12.4) 4.3(5.9) Anxiety+CPSMd 4.42.5 4.22.5 4.52.6 Anxiety–CPSMe 6.71.8 1.71.5 1.0

Totalproceduretime(min) 7.53.0 7.62.4 8.16.9

Tolerability(%) 37(94.9) 14(66.7) 22(81.5)

VRS,VerbalRatingScale;CPSM,ContinuousPainScoreMeter;VAS,VisualAnalogueScale;AUC,areaunderthecurve;PPS,peakpainscore;APS,averagepainpersecond;IQR, interquartilerange.

a

Median(IQR)unlessotherwisestated.

b

MeanVRSSDofthewomenwhousedtheCPSMcorrectly.

c

MeanVRSSDofthewomenwhodidnotusetheCPSMcorrectly.

d

MeanbaselineanxietySDofthewomenwhousedtheCPSMcorrectly.

e

MeanbaselineanxietySDofthewomenwhodidnotusetheCPSMcorrectly.

Table3

CorrelationbetweenVerbalRatingScale(VRS)andContinuousPainScoreMeter (CPSM)outcomes.

Procedure r-value p-value

Colposcopy CPSM-AUC 0.82 0.001 CPSM-PPS 0.86 0.001 CPSM-APS 0.82 0.001 Ovumpick-up CPSM-AUC – 0.053 CPSM-PPS 0.80 0.001 CPSM-APS 0.55 0.009 Hysteroscopy CPSM-AUC 0.39 0.042 CPSM-PPS 0.77 0.0001 CPSM-APS 0.43 0.025

VRS,VerbalRatingScale;CPSM,ContinuousPainScoreMeter;AUC,areaunderthe curve;PPS,peakpainscore;APS,averagepainpersecond.

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registeredasmostpainfulwerepassageofthescopethroughthe cervical canal (deﬁned as the period betweenthe start of the passage of the external osuntil the end of the passageof the internalos,andthuswhenthescopereachedtheuterinecavity), cervicaldilatation,synechiolysisandpolypresection.

To illustrate the accuracy of the various pain scores using patienttolerancetoaprocedureasareferencetest,variousROC curveswereplotted(seeFig.4).TheareaundertheROCcurvewas largestforVRSscore(0.89)andCPSM-PPS(0.86).TheAUCsofthe ROCcurvesforCPSM-AUCandCPSM-APSwereboth0.66.

Fig.3.BoxandWhiskerplotsofVerbalRatingScale(VRS)andContinuousPainScoreMeter(CPSM)scoresinpatientswhoreportedtheoutpatienthysteroscopytobe tolerable(yes)vsintolerable(no).

Table4

Painscoresrelatedtovariouspartsofahysteroscopyprocedure. Hysteroscopy

Speciﬁcpartofthehysteroscopy n CPSM-AUC [median(IQR)]

CPSM-PPS[median(IQR)] CPSM-APS[median(IQR)] Cervicalpassagehysteroscope 27 359.0(1381.4) 2.3(4.9) 5.6(8.0)

Dilatatingcervix 5 343.1(565.3) 1.9(6.4) 6.2(24.3) Insertingspeculum 9 23.8(82.6) 0.1(1.6) 0.9(3.4) Tenaculumplacement 7 0.4(33.6) 0.0(0.2) 0.0(9.2) Cervicalblock 6 6.3(30.7) 0.1(0.6) 0.2(1.0) Resectionofpolyp 10 106.8(3608.5) 1.7(5.5) 0.9(14.2) Synechiolysis 2 121.5(-) 2.4(-) 0.1(-) Endometrialbiopsy 3 88.7(-) 0.9(-) 1.4(-)

InsertingIUDafterhysteroscopy 2 37.5(-) 0.1(-) 1.3(-)

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Discussion Mainﬁndings

ThisstudyconfirmedthefeasibilityoftheuseoftheCPSMfor threedifferentgynaecologicaloutpatientprocedures.Afterproper instruction, 91 of 108 patients(84 %) managedto operatethe device adequately. However, during pain measurements, some patientshad difficultieshandlingthe CPSMcorrectly.Subgroup analysiswas performedafterwards,andtheresultsbetweenthe groupwhooperatedtheCPSMcorrectlyandthegroupwhodidnot operate the CPSM correctly were not significantly different; however, thismayhavebeeninfluenced bytherelativelysmall sample size. In general, higher VRS scores were registered in women who failed to usethe CPSM correctly; 65 %of the 17 patients whodid notusethe CPSMcorrectlyscoredabovethe median score for thepatients who usedtheCPSM correctly. It appearstobemoredifficulttoexecutethistaskwhileexperiencing severepain;however,bycontrollingtheCPSMslider,patientsmay feelagreaterdegreeofcontrol,whichcouldbeevenmorerelevant foranxiouspatients.Theseitemsmaybethetopicoffuturestudies. TheVRSscorewaslinearlycorrelatedwithalltheCPSMscores

(CPSM-AUC, CPSM-PPS and CPSM-APS) during all assessed

procedures. CPSM-PPS showed the strongest correlation with the VRS score. Both the VRS score and CPSM-PPS showed the strongestcorrelationwithpatientjudgementconcerningwhether the procedure was tolerable or intolerable under the given circumstances.

Interpretationoftheresults,clinicalimplicationsandfuture perspectives

Accuracyofthenewpainscoresobtainedbyelectronicpain measurementwiththeCPSMwashighandcomparablewiththe commonlyusedVRS.Giventhehighcorrelationbetween CPSM-PPSandpatientjudgementofthe(in)tolerabilityoftheprocedure, anditsstrongcorrelationwiththeVRSscore,itcanbeconcluded thatpeopleappeartohavethebestrecalloftheworstexperienced pain.Itispossiblethatthismomentrepresentsthepainperception oftheentireprocedure.ThegreatestadvantageoftheCPSMover

theVRSisitsability tomeasurecontinuouslyduringtheentire procedure, providing information on all individual steps. This allows the detection of specific steps that are most painful, measuredmoreobjectively.ThepotentialapplicationsoftheCPSM are numerous. It can reveal, for example, specific patient characteristicsinrelationtopainperception,withtheresultthat strategiestoreducepaincanbedevelopedatanindividuallevel andimprovepatienttolerancetoalltypesofprocedures.Itcould alsobeusedtostudytheeffectoforalpainkillers,tocomparelocal anaestheticswithplaceboduringvariousofficeprocedures,andto determinetheconsequencesofusingdifferentintrauterineagents duringsonohysterographyorhysterosalpingography.Inaddition, non-pharmacologicaleffectsonpaincanbestudiedindetail,such asthepresenceofanurseguidingthepatient,ortheuseofmusic orimages.Workhasalreadycommencedonthisbytheauthors’ studygroup,comparingtwotypesofgelsusedduringgelinfusion sonography, and a comparative study was performed using misoprostol vs placebo before hysteroscopy to determine the effectonpain[25].Foryears,effortshavebeenmade,invain,to discover the best method for pain reduction in outpatient procedures,especiallyduringhysteroscopy.However,thereisstill nounambiguousadvice,eitherpharmacologicalor non-pharma-cological[26–28].TheCPSMmaybethesolutiontoprovidemore clarityandinsighttoreducepainduringtheseprocedures.

TheCPSMresultsaredepictedgraphically,butanotherpossible featureisthatfeedbackcouldbegivenbyasound.Highertones reﬂectmorepain.Thissoundcanbeswitchedonoroff,andthe intensitycanbechanged.Therefore,theCPSMcouldtheoretically be used for immediate feedback to the surgeon, potentially resultingin less paindue tothesurgeon’s ability toadjust the treatmentdirectlyinordertoreducepain.Inaddition,thiscould reducepainduetochangesinthepatient’sperceptionofpain,with theknowledge thatthere is immediate feedback and therefore morecontrol.Futurestudiesshouldbeundertakentodetermineif theuseoftheCPSMdoesaltertheperceptionofpain.

Various studies have reported that fear and anxiety may aggravatepain[13–15].ApartfromtheVRSscoresincolposcopy, the present results did not support this ﬁnding. Remarkably, women reported higher anxietyscores before colposcopythan before ovum pick-up, while lower pain scores were reported duringcolposcopy.Itishypothesizedthatapartfromthefearof pain, other factors may play a role, such as the fear of the histologicalresult(i.e.cervicalcarcinoma)inthesepatients. Strengthsandlimitations

Allprocedureswereperformedunderstandardizedconditions, andintervariability onlyexistedbetweenpatients. All examina-tions wereundertaken bywell-trained and experienced practi-tioners, so the factor time or disability that comes with inexperiencedidnotplay arole in thisstudy. Continuous real-time pain measurement was performed during three different gynaecological procedures, allowing comparison between the patientgroups,andalsoallowingevaluationofitsfeasibilityduring differentprocedures.

ThenewlyobtainedCPSMpainscoreswerecomparedwitha validated pain score (VRS), and the CPSM itself is a validated instrument.Therefore,measurementaccuracyislikely.

Alimitationofthisstudyisthatthethreestudygroupswere relatively small. Additionally, some selection bias cannot be excluded because study registration was only executed when theCPSMandtheresearcherwereavailable.Inthreeof108cases, softwarefailureoccurred.Softwareupgradeswillpreventthisin futurestudies.Anotherlimitationofthisstudyisthatthedatawere acquiredin2011andanalysedin2019.However,itisbelievedthat thecurrentdataarestillhighlyinnovativeandrelevantfordaily

Fig.4. Receiveroperatingcharacteristiccurveofpainoutcomesusingtolerabilityof thehysteroscopyasthereferencetest.Largestareasunderthecurvewerefoundfor theVerbalRatingScalescore(VRS;0.89)andtheContinuousPainScoreMeterpeak painscore(CPSM-PPS;0.86).FortheCPSMareaunderthecurve(CPSM-AUC)and CPSMaveragepainpersecond(CPSM-APS),theareasunderthecurvewereboth 0.66.

(8)

practice.Nostudiesoncontinuouspainmeasurementhavebeen publishedinthelast8years.

Conclusion

Ingeneral,patientsundergoingagynaecologicalprocedurein an outpatient setting are able to operate the CPSM whilst undergoing the procedure, and the measured CPSM outcomes correlate well withthe commonly used VRS. One of the main advantagesofpainevaluationusingtheCPSMovertheVRSisthat theCPSMreportsthepainoutcomesofvariousstimuliduringone procedure, separately. Both the CPSM-PPS and the VRS score correlate well withthe judgement of women concerningtheir tolerance orintoleranceoftheprocedureinthecurrentsetting, and this can beusedduring future studiestooptimizevarious outpatientproceduresingynaecologyinordertoreducepain. Contributiontoauthorship

ContributorsMLO,HBRandJHUdesignedthestudy.PKEand WHEwereinvolvedinthestudydesign.MLOincludedpatients. MLOand BLIanalysedthedata.MLOwrotethemanuscript.All authorscriticallyreviewedandapprovedtheﬁnalmanuscript.JHU istheguarantor.

Detailsofethicsapproval

Approval, date 01-06-2011,was obtained from The Medical EthicsReviewCommitteeofVUUniversityMedicalCenterthatis registered with the US Ofﬁce for Human Research Protections

(OHRP) as IRB00002991. The FWA number assigned to VU

University Medical Centeris FWA00017598. Thestudy is regis-trated at the ISRCTN registry and the clinical trial number is: ISRCTN15427669.

Funding None.

DeclarationofCompetingInterest

The authors declare that they have no known competing ﬁnancial interests or personal relationships that could have appearedtoinﬂuencetheworkreportedinthispaper.

Acknowledgements

Theauthorswishtothankallofthepatientswhoconsentedto participateinthisstudy;EwoutBoschwhohelpedwith develop-mentofPainScope;theirco-workersF.Poelsma,M.Vreeburg,S. Graumans, E. van de Oudeweetering and A. Zikmund for their supportiveactivities;andalltheotherparticipantsinvolvedinthis study.

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