Epidemiology of contact allergy: an estimation of morbidity employing the clinical epidemiology and drug-utilization research (CE-DUR) approach

Clinical epidemiology (CE) is considered unable to estimate morbidity concerning either contact sensitization (CS) or allergic contact dermatitis (ACD) at the population level. Drug-utilization research (DUR) methods estimate the morbidity of suitable diseases based on prescription data for disease-specific drugs. Our objective was to estimate population figures for incidence and prevalence of ACD and CS based on sales data for patch test material in Germany and on patient data from the Information Network of Departments of Dermatology (IVDK). Approximately 600,000 standard series are sold per year in Germany, according to the 2 main manufacterers. This raw sales figure was corrected for certain effects (discarded preparations, proportion of formerly patch-tested patients, proportion of patients with ACD seeking medical advice) to obtain an estimate of the denominator of patients eligible for patch testing annually, and combined with patch test results from the Information Network of Departments of Dermatology (IVDK). In 17.8% (of 9,266 IVDK patients) ACD was established. Extrapolated to the general population, an incidence of ACD of between 1.7 and 7 per 1000 per year was estimated, depending on whether conservative or more liberal assumptions concerning the above effects were made. Of 78,067 IVDK patients tested between 1992 and 2000, 46.8% had at least 1 positive reaction (+ to + + +), and 22.7% had at least 1 stronger positive reaction (+ + or + + +).The 9-year prevalence of CS was estimated to lie between 4.0% and 16.6% for the first outcome, and between 2.0% and 8.1% for the second. Concerning single allergens, 1.9-4.5 million individuals are probably sensitized to nickel, and 1.4-3.4 million to fragrance mix among the German population of 82 million inhabitants. The morbidity data found in this study are in good accordance with data from population-based epidemiological studies. In comparison to these, the CE-DUR approach seems to be an economically feasible method to estimate continuously the population impact of ACD and CS.