Isolated and concurrent prevalence of sensitization to transition metals in a Spanish population

Positive patch test results to transition metals (nickel sulphate, palladium chloride, cobalt chloride and potassium dichromate) alone and in combinations with one another are well known. Numerous factors may play a role in isolated and concurrent sensitization to these allergens. This study aims to describe the isolated and concurrent prevalence of sensitization to transition metals in a Spanish Dermatology Department, between 2000 and 2005, and to determine the prevalence of concomitant positive patch test reactions to different transitional metals. Patients (N = 1092) were tested with the standard series of our Allergic Contact Unity, using a standardized technique. Data from these patients were recorded on a computer entry form and analysed. Statistical analyses to evaluated associations of metal contact allergy were performed, and we evaluated the concordance among these associations of transition metals. Three hundred twenty (29.3%) patients reacted positively to nickel, 128 (11.7%) to palladium, 118 (10.8%) to cobalt and 82 (7.5%) to chromium. The prevalence of positive reactions to metals was 32.4%. The association of palladium-nickel was the most frequent, with an acceptable concordance (k = 0.46). This study illustrates that concomitant positive patch test reactions to different transitional metals are frequently seen in patients with allergic contact dermatitis. Our results reflect the high prevalence of sensitization to nickel in Spain.