The ‘overall yield’ with the baseline series – a useful addition to the array of MOAHLFA factors describing departmental characteristics of patch tested patients

Background. The proportion of patients with a positive patch test reaction to at least one allergen from the baseline series differs between departments. Objectives. To further define the above mentioned proportion, termed the ‘P’ measure, to examine factors associated with this measure, to describe its variation over time and between centres, and to discuss possible uses. Patients and methods. Eighteen departments have been ‘long-term’ participants in the Information Network of Departments of Dermatology (IVDK; www.ivdk.org), that is, since 1995 (1997 in two cases). In these departments, 80 919 consultations for patch testing with the baseline series, in the composition of the series valid at that time, were documented until December 2009. Bivariate and multifactorial analyses addressed factors associated with being patch test-positive to at least one baseline series allergen. Results. Of the study population, 46.5% had at least one positive test reaction, with considerable variation being seen between centres and a general decline during the study period. Among other factors, female sex, occupational causation and a high suspicion of allergic contact dermatitis were significantly associated with having at least one positive patch test reaction to the baseline series. Conclusions. The ‘P’ measure should prove useful as another perspective on departmental characteristics, and should be reported along with established variables (MOAHLFA index).