Accuracy of questions related to allergic contact dermatitis

Background: The ability of a physician to select individuals likely to benefit from patch testing depends on his or her ability to interpret responses to enquiries related to contact allergy. The significance of such responses to questions of nickel, fragrance and colophon allergy is unclear. Objective: The specificity, sensitivity and predictive value of questions relating to nickel, fragrance and colophony allergy were determined. Method: A total of 258 patients attending for routine patch testing were questioned about skin reactions to nickel, fragrances and Elastoplast (Smith and Nephew Healthcare, Hull, England). All subjects were then patch tested to nickel, fragrance mix, and colophony. Responses to questions were compared with patch test results. Results: The sensitivity of questions relating to nickel, fragrance, and colophony was 82%, 49%, and 71%, respectively. The specificity of the same questions was 77%, 79%, and 90%; the positive predictive value was 54%, 46% and 29%, respectively. After adjustment to include clinical relevance, the sensitivity of nickel questions rose to 100%. Conclusion: These data permit greater understanding of the role of patient history in selection of patients for patch testing.