Background: Instruments for field diagnosis of eczema are increasingly used, and it is essential to understand\r\nspecific limitations to make best use of their strengths. Our objective was to assess the validity of ISAAC and UK\r\nWorking Party criteria for field diagnosis of eczema in children.\r\nMethods: We performed a cohort study in urban Brazil. Parents/guardians of 1,419 children answered ISAAC phase\r\nII questionnaire. Children were examined for skin lesions (UKWP protocol). Two dermatologists examined most\r\ncases of eczema (according to ISAAC or UKWP), and a sample without eczema.\r\nResults: Agreement between repeat questionnaires on the filter question was poor (kappa = 0.4). Agreement\r\nbetween the 2 dermatologists was fair (kappa = 0.6). False positive reports included scabies in 39% of ISAAC cases\r\nand 33% of UKWP cases. Sensitivity and PPV were low (ISAAC: 37.1% and 16.1%; UKWP: 28.6% and 23.8%).\r\nSpecificity and NPV were high (ISAAC: 90.0% and 96.6%; UKWP: 95.3% and 96.2%). One-year prevalence of eczema\r\nwas 11.3% (ISAAC), 5.9% (UKWP) and 4.9% (adjusted dermatologist diagnosis). Point prevalence of scabies (alone or\r\nnot) was 43%, 33% and 18%, in eczemas according to ISAAC, to UKWP and to dermatologists. The reasons why\r\nchildren with eczema were not identified by ISAAC or UKWP were wrongly denying dry skin, itchy rash or personal\r\nhistory of atopic diseases. A limitation is that questionnaire was already validated in Brazil, but not field tested in\r\nthis specific setting.\r\nConclusions: Studies using UKWP or ISAAC criteria should include a validation arm, to contribute to the\r\nunderstanding of potential limitations of their use in different contexts and to explore solutions. We list specific\r\nrecommendations.
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