Self-reported hand eczema:: symptom-based reports do not increase the validity of diagnosis

Background Hand eczema is a common skin disease that affects about 10% of the general population of working age in Sweden. The resulting long sick-leave periods and need for changes of work and re-training put an economic burden on society, and there is an interest indeveloping cost-effective epidemiological surveillance instruments such as a screening questionnaire. Objectives In a search for a simple screening questionnaire for hand eczema we compared the validity of a question about the presence of hand eczema with hand eczema diagnosis based on self-reported signs. Methods Consecutive patients (n = 95) referred for hand eczema and people in an ongoing epidemiological survey (n = 113) participated in the study. Before seeing an experienced dermatologist they had to: (1) answer a short questionnaire about current signs and symptoms from the hands; and (2) state whether they had hand eczema on the day of examination. The minimum criteria for hand eczema diagnosed by the dermatologist ('gold standard') were erythema and papules or vesicles, or erythema and scaling and fissures/lichenification. Results Of the 208 persons examined 93 fulfilled the criteria for hand eczema according to the 'gold standard'. Hand eczema diagnosis based on clinical signs reported in the questionnaire by the participants gave a sensitivity of 0.62 and a specificity of 0.87 in comparison with the dermatologists' diagnoses. Regarding the question about current hand eczema, agreement was good between the participants' and the dermatologists' judgements, giving a sensitivity of 0.87 and a specificity of 0.79. Comparing clinical signs reported by the participants and the findings by the dermatologists, the best agreement was for fissures, with a kappa -value of 0.65 (95% CI 0.55-0.75), and the poorest was for papules with 0.47 (95% CI 0.32-0.62). Conclusions It was difficult for the individual to identify skin signs compatible with the clinical diagnosis of hand eczema. Asking 'Do you have hand eczema?' had high sensitivity and specificity compared to the suggested gold standard for hand eczema. However, the validity of a screening questionnaire depends on the type of population investigated.