Contact allergy to topical drugs: prevalence in a clinical setting and estimation of frequency at the population level

Abstract

Objectives: To estimate the prevalence of contact allergy (CA) to a set of topical drugs patch tested in the research network IVDK (Information Network of Departments of Dermatology; www.ivdk.org) between 1995 and 2004, and to extrapolate these clinical data to the German population.

Methods: Clinical data comprised results of allergy patch tests with topical drugs in patients with suspected CA. Clinical epidemiology and drug utilization research (CE-DUR) methods were employed to grossly estimate the incidence of CA to these topical drugs during two 5-year periods (1995-1999 and 2000-2005) in the German general population. To estimate the number of persons eligible for patch testing (with the topical drugs) on a general population level, sales data of patch test material were obtained. By relating this denominator to the CA frequency observed in the IVDK, the incidence of CA to selected topical drugs in the German general population was crudely estimated.

Results: In general, topical aminoglycosides showed the highest CA frequencies and, except for gentamicin sulfate, frequencies of CA to all other allergens tested were lower in the 2nd period of analysis. According to the medium model, 1-year incidence rates ranged from 1 (hydrocortisone-17-butyrate) to 29 persons/100,000 (neomycin sulfate) in the general population (1995-1999).

Conclusion: The CE-DUR approach yielded incidence estimates of CA to relevant topical drugs in the German general population, which, despite their limited precision in absolute terms, illustrate the relative frequency of this particular adverse effect. However, comparative risk assessment should preferably take exposure information into account.