Identification of subjects with atopic dermatitis in questionnaire studies

The performances of 3 different atopic dermatitis questions from the Danish translation of the Nordic Occupational Skin Questionnaire (NOSQ-2002) were compared with respect to their ability to identify subjects with atopic dermatitis in workplace studies. The wording of the questions were: 'Have you ever had an itchy rash that has been coming and going for at least 6 months, and at sometime has affected skin creases?' (UK question), 'Have you ever had eczema on the fronts of the elbows or behind the knees?' (Nordic-S5a) and 'Have you ever had childhood eczema?' (Nordic-S5b). In a group with occupational exposure including the forearms (gut cleaners) twice as many (44%) answered 'Yes' to the UK question compared with 2 other studies on dairy workers and hospital employees. The question Nordic-S5b gave rise to less positive answers than expected. The Nordic-S5a question gave rise to 15%, 10% and 15% positive answers, respectively, and these frequencies seemed to be independent of the workplace exposure. In conclusion, we recommend the Nordic-S5a question as the question to be used for identification of subjects with atopic dermatitis in adult workplace populations. Furthermore, we found that the UK question led to over-reporting in an adult workplace population with occupational exposure including the forearms.