British Journal of Dermatology 1995; 133: 941-949.

A protocol for recording the sign of flexural dermatitis inchildren

H.C.WILLIAMS, H.FORSDYKE, G.BOODOO, R.J.HAY AND P.G.J.BURNEY*St John's Institute of Dermatology and *Department of Public Health Medicine, United Medical and Dental Schools,St Thomas' Hospital, London SEI 7EH, U.K.

Accepted for publication 20 February 1995

Summary Tiie presence of visibie fiexurai dermatitis is a icey feature in diagnosing atopic dermatitis. Wedescribe a protocoi for recording tiiis sign in popuiation-based studies, wiiicii couid be used bysuitabiy trained non-dermatoiogists. Tiie protocoi was deveioped using a standard set of photograpiisand accompanying instructions, wiiich define tiie terms 'dermatitis' and 'iiexurai'. Wiien assessedduring a survey of sicin disease in primary sciiooiciiiidren, tiiere was exceiient agreement between atrained nurse and a dermatoiogist with regard to tiie presence or absence of this sign in 73consecutive chiidren, with perfect agreement in 71 chiidren (97%), and a chance correctedagreement index (icappa statistic) of 0-90 (95% confidence intervai [CI] 0-77-0-99). Agreementbetween two nurses on 114 consecutive schooichildren was not quite as good, with perfectagreement in 102 chiidren (90%), and a icappa vaiue of 0-51 (95% CI 0-26-0-77). The protocoiis easy to perform, does not require chiidren to undress, tai?es < 1 min to carry out, and is highiyacceptabie to chiidren and staff. This protocoi may be usefui in standardizing the assessment of atopicdermatitis in popuiation studies of chiidren.

It is important that ciinicai questionnaire or physicalexamination protocols are subject to the same rigorousquaiity evaiuation as iaboratory techniques, if they areto measure what they purport to measure when used bydiiTerent woricers throughout the wdrid.' Fiexuraidermatitis is an important diagnostic feature of atopicdermatitis,^"^ and several studies have made speciaireference to this sign.^'^~^ Aithough a dermatoiogistmay know exactiy what he or she means by theterms 'dermatitis' and 'flexural' when referring toindividuai cases, the criticai issue is whether diiTerentdermatologists and physicians from around the woridare designating the same entity when referring tolarge groups of people.^° Some of the reporteddifferences in the prevalence of atopic dermatitisbetween countries" could be due to differences inthe way 'fiexurai dermatitis' has been interpreted bydifferent physicians.

Although truncal and other non-flexural sites arecommoniy affected in atopic dermatitis,^^ it is thepresence of fiexurai dermatitis (or cheeks and outeraspects of limbs in you.ng children) which serves asthe most usefui discriminating feature for distinguishing

Correspondence: Dr Hywel Williams. Department of Dermatology.Queen's Medical Centre. University Hospital, Nottingham NG7 2UH.U.K.

atopic dermatitis from other infiammatory dermatoses.^' ^Some have even used fiexurai dermatitis as a referencestandard to evaiuate other diagnostic features of atopicdermatitis.'^ Visible fiexurai dermatitis is the onlyphysical sign that is required to be recorded, in con-junction with the five other historical features, in theU.K. Working Party's diagnostic criteria for atopicdermatitis^'' (Table 1). As these criteria are designedfor use in epidemiologicai studies in which ciinicaiexamination of a large number of individuais by adermatoiogist may be impractical, it is important tohave an instrument for recording the sign of fiexuraidermatitis which could be easily learned by suitablytrained non-dermatoiogists.

This paper summarizes the development of a protocolfor recording the sign of visible fiexurai dermatitis,together with its application by non-dermatoiogists ina fieid setting.

Methods

Development of the instrument

We deveioped a protocol based on a set of standardphotographs which illustrate the two concepts of'dermatitis' and 'fiexurai'.

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942 H.C.WILLIAMS etal.

Table ] . The newly proposed diagnostic guidelines for atopicdermatitis

MUST HAVE:An itchy skin condition (or parental report of scratching or rubbing ina child)

PLUS 3 OR MORE OF THE FOLLOWING:1 History of involvement of the skin creases such as folds of elbow;;,

behind the knees, fronts of ankles or neck.2 A personal history of asthma or hay fever (or history of atopic

disease in a first-degree relative in those under 4).3 A history of a generally dry skin in the last year.4 Visible flexural dermatitis (or dermatitis involving the cheeks/

forehead and outer aspects of the limbs in children under 4).5 Onset under the age of 2 (not used if child is under 4).

Most of the definitions used in the protocol wer(3developed from the U.K. Working Party's diagnosticcriteria for atopic dermatitis,' and were refined afterfurther piloting on dermatological out-patients.Reference photographs were then chosen to illustrat(3what is meant by the terms 'dermatitis' and 'flexural'. Inaddition to providing typical examples of particularsigns, care was taken to include many 'borderline'examples of signs which researchers typicall;^encounter in real life. The piloting stage also identifieda number of clinical situations which could caus(;difficulty, and these have also been illustrated in aspecial section at the end of the protocol. In view ofthe possible different appearance of atopic dermatitis inblack skin to an untrained eye,^' at least one-quarter ofthe photographs depict changes in a darkly pigmentedskin. In order to account for possible differences in thedistribution of atopic dermatitis in younger children,^'dermatitis present on the cheeks and outer aspects ofthe limbs was also included in the protocol for childrenunder the age of 4 years.''^ Independent views on thepractical application of the protocol were sought fromout-patient nurses from two hospitals, and modifica-tions were made accordingly. The protocol is publishedin full at the end of this article.

Testing in the field

Two nurses were trained by a dermatologist to recordflexural dermatitis according to the study protocol, for2 h each week for 3 weeks, on dermatology out-patientsubjects. The nurses were first asked to committhemselves to a response, and they were thenencouraged to discuss any difficulties and sources ofdisagreement.

Between-observer agreement in recording this signwas then tested on primary schoolchildren in WestLambeth. This setting was chosen because of itsethnic mixture. The children, from three differentschools, were aged from 3 to 11 years (mean age of 7,standard deviation of 2-4), and the sample containedthe same proportion of male and female children. Theoverall point prevalence of atopic dermatitis in thisschool population, based on examination by apaediatric dermatologist (A.C.P.), was 8-5%. Agree-ment between a dermatologist (H.C.W.) and one of thenurses in recording fiexural dermatitis was tested in 73consecutive children (one class randomly selected fromeach school). Agreement between the two nurses in therecording of this sign was then tested in a separatesample of 114 consecutive children (one class randomlyselected from each of the three schools). Each observerrecorded the sign of fiexural dermatitis independently,without discussing their findings. The protocol wasavailable for reference throughout this exercise. Ethicalpermission for this study was granted by West Lambethethics committee, and written parental consent wasobtained to examine the children. Results of between-observer agreement have been expressed as 2 x 2contingency tables, and summarized by the meanpair agreement index (the number of pairs ofobservations in which there was perfect agreement)and the kappa statistic^*' (a chance corrected measureof agreement).

Results

Agreement between dermatologist and nurse

These results are summarized in Table 2(a). There wasperfect agreement between the nurse and dermatologist(i.e. both agreed that the sign was present, or bothagreed that the sign was absent) in 71 of 73 patients.This corresponds to a mean pair agreement index of97%, and a K value of 0'90 (95% CI 0'77-0-99). If thedermatologist's findings are considered as a referencepoint, the sensitivity and specificity of the nurse'sexamination findings are 92% (11 of 12) and 98%(60 of 61), respectively.

Agreement between the two nurses

The two nurses were in perfect agreement in 102 of 114children seen consecutively, corresponding to a meanpair agreement index of 90% and a K value of 0-51(95% CI interval 0-25-0-77).

© 1995 British Association of Dermatologists. British Journal of Dermatology. 133, 941-949

RECORDING FLEXURAL DERMATITIS IN CHILDREN 943

Table 2. Agreement (a) between a dermatologist and nurse, and (b)between two nurses, in recording the sign of visible flexural dennatitisin 73 and 114 consecutive primary school children, respectively

(a) DermatologistNurse 1

Sign presentSign absent

Total

(b) Nurse 1Nurse 2

Sign presentSign absent

Total

Sign present

111

12

84

12

Sign absent

16061

894

102

Total

126173

1698

114

Although inspection of the cross-diagonals inTable 2 (b) suggests that nurse 2 had a tendency torecord the sign as being present more frequently thannurse 1, there was no statistical evidence to supportsuch a bias (P = 0-39, McNemar's test^^).

When analysed by school, it could be seen thatagreement between the two nurses improved withtime. Mean pair agreement index and kappa valueswere 83% and -0-1 , 95% and 0-5, and 89% and 0-6in schools 1, 2 and 3, respectively.

Detailed analysis of the individual disagreementsbetween the two nurses suggested that one area ofconfusion was the inclusion of post-inflammatorypigmentation related to friction on the fronts of theankles in dark skins. Other than this, there was nosuggestion that skin colour or age were predictors ofdisagreements between observers.

Acceptability and convenience of protocol

None of the children in this exercise refused examina-tion under the conditions specified by the protocol. Bothof the trained nurse observers and the dermatologistfound the protocol easy to use, and examination of eachchild took about 55 s to complete.

Discussion

Our protocol for recording the sign of visible flexuraldennatitis was required to be: (i) valid and repeatable:(ii) acceptable to children; (iii) rapid and easy toperform; (iv) capable of being carried out by a trainedindividual; and (v) equally applicable to young childrenand children with darkly pigmented skin. This study

suggests that the proposed protocol adequately fulfilsthese requirements.

Validity and repeatability

Validity, which refers to the ability of the sign tomeasure what it purports to measure, ̂ ^ has alreadybeen established indirectly in a previous study, bydemonstrating the ability of the sign to discriminatebetween atopic dennatitis and other skin conditions ornonnal skin.̂ Direct comparison of the nurse's findingswith those of the dermatologist as a reference standardreveals high sensitivity and specificity, although it couldbe argued that a dermatologist is not necessarily likelyto be more 'correct' than the trained nurse in recordingthis sign, as specified by the protocol. Because of theuncertainty of a suitable reference standard, it isperhaps more reasonable to simply test the degree towhich observers, be they nurses or dermatologists,agree with each other in a field setting, where theprotocol will be used. Even after allowing for chanceagreement (which is higher in population studies thanin hospital studies, because of a greater proportion of'normals'^^), agreement between a nurse anddermatologist in this study was very high (/c = 0-9).Actual agreement was still high between the two nurses(mean pair agreement index of 90%), but chancecorrected agreement (K = 0-51) was lower. Althoughthis K value of 0 51 is rated as good agreement by someauthorities,^*'^^ we regard a K value of 0-75 and meanpair agreement index of 0 90 as a reasonable target forbetween-observer agreement in future studies.

i

Acceptability

A critical factor in determining high response rates tosurveys which involve contact with normal children iswhether or not the survey procedures are acceptable tochildren and parents. None of the children refused to beexamined in this study, but further testing in teenageand adult groups is needed before an equally highacceptability can be claimed in these groups. Becauseonly the arms, legs, neck and face need to be inspected,ascertainment of the sign was rapid (<1 min per child),and very easy to perform, as it was not necessary toremove the clothes.

Trained observers

This study has shown that ascertainment of the sign offlexural dermatitis can be carried out satisfactorily by

1995 British Association of Dennatologists, British Journal of Dermatology, 133, 941-949

944 H.C.WILLIAMS etal.

suitably trained non-dermatologists. The two nurses inthis study found the protocol easy to follow, andbecause ascertainment of visible flexural dermatitiistook <1 min per child, the protocol could be useful forexamining large numbers of subjects in future;epidemiological studies. It is even possible that suitablytrained non-dermatologists may be more reliable thandermatologists in recording this sign as defined byour protocol, as they might be less influenced bj'preconceived ideas of flexural dermatitis.^"

Age and ethnic group

We found no particular difficulties in using the protocolin young children and in children with darklypigmented skin, apart from the possible inclusion ofpost-inflammatory pigmentation due to friction fron:ishoes on the fronts of the ankles in black children. Thispoint has now been emphasized at the end of the;protocol instructions, by pointing out that flexuraldermatitis should not be recorded at this site unlessthere is convincing accompanying surface change.

Future use of the protocol

Some recommendations are necessary for other groupswishing to use this protocol. We suggest that observersshould be given a period of training, preferably by adermatologist. Good natural lighting is necessary toascertain the sign, especially in dark skins, and the:observer should be seated at the same eye level as the:children. The wearing of sports kit by children greatlyfacilitates rapid examination. It is also essential thatobservers undertaking a field survey undergo some form,of quality control monitoring. We are currently in theprocess of compiling a set of reference photographs/slides to serve as a quality control test. Although we:recommend that ascertainment of visible flexura)dermatitis should be used in conjunction with theU.K. Working Party's diagnostic criteria for atopicdermatitis, it may be useful as a point prevalencemeasure in its own right. For this reason, individualresponses to the presence of visible flexural dermatitisshould be retained, in addition to composite measuressuch 'atopic dermatitis yes/no'. In children under theage of 4, it might also be useful for future studies tostipulate whether the dermatitis was flexural, orwhether it affected the cheeks or outer aspects of thelimbs. It should also be pointed out that the protocoldescribed in this paper has only been tested in childrenaged 3-11 years, and that extension of the use of the

instrument to adults requires further study. Thepresence of eyelid allergic contact dermatitis andlichen simplex in adults, for example, is likely todecrease the specificity of our protocol if it was to beused alone as a point prevalence measure in adults. Forthis reason, we recommend that periorbital and anklelesions are not included in studies which deal solelywith adults.

Further development

It is possible that other groups may not achieve a degreeof agreement between their workers similar to thatwhich was found between the nurses in this study,who were motivated, and familiar with skin disease.Testing of the protocol in other countries is planned, asare further studies in different age groups, such as veryyoung children, teenagers and adults. We regard thisproposed protocol as an evolving tool, and suggestionsas to how the protocol might be improved or adapted tospecial local needs are welcomed.

Acknowledgments

We are grateful to Stiefel (U.K.) Ltd for their help withprinting and laminating the protocol. Hywel Williamswas supported by the Wellcome Trust when this workwas carried out.

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