Ascertainment of hand dermatitis using a symptom-based questionnaire; applicability in an industrial population

In this study, the applicability of a symptom-based questionnaire on hand d ermatitis was assessed in a population of rubber workers. The questionnaire was previously validated in a study among nurses. 224 subjects employed in 9 different companies completed a questionnaire on skin complaints. Subseq uently, 202 workers attended the physical examination of the skin by a derm atologist. The ascertainment of skin complaints according to the questionna ire was compared to the medical evaluation. The 2 different diagnostic tool s used for assessing dermatitis resulted in dissimilar estimates of the pre valence of active hand dermatitis, ranging from 6.9% to 38.1% of all worker s. Using the medical evaluation as 'gold standard' we observed a moderate s ensitivity and specificity (respectively 71.4%; 95% CI: 47.7-95.1 and 76.1% ; 95% CI: 70.0 - 82.2), a low positive predictive value (18.2%; 95% CI: 8.0 -28.4) and a high negative predictive value (97.3%; 95% CI: 94.7 -99.9) for the classification based on the self-administered questionnaire. When eval uated against 'first symptoms of dermatitis' the sensitivity decreased, whi le the specificity remained almost the same. The deviant findings between t he present and the original validation study of the same questionnaire amon g nurses hamper its applicability in populations with different occupations . Therefore, if questionnaires are to be used, validity studies have to be carried out to evaluate differences in perception of skin diseases between different (occupational) populations.