Patch testing reactions to a standard series in 608 patients tested from 1990 to 1997 at Massachusetts General Hospital

image: Patch testing is a useful diagnostic tool when allergic contact dermatitis is suspected clinically. image: This study describes the results of patch testing performed from January 1, 1990 to June 1, 1997 at the Massachusetts General Hospital Contact Dermatitis Clinic. The findings are compared with those previously reported by the North American Contact Dermatitis Group (NACDG). image: Data were collected from chart review and analyzed. Patients included in the study underwent patch testing to the full European standard series of allergens. A standardized patch testing technique was used, and readings were performed by a single observer. image: A total of 608 patients were patch tested to a screening tray of 24 allergens; 69.9% were women. At least one positive patch test reaction was observed in 60.0% of patients. The most common sensitizers were nickel sulfate, fragrance mix, potassium dichromate, cobalt chloride, balsam of Peru, quaternium-15, and neomycin sulfate. The sensitization rate to potassium dichromate (9.4%) was higher than has been reported by the NACDG. A statistically significant difference in the sensitization rate in men and women was observed for nickel, quinoline mix, epoxy resin, and formaldehyde. The prevalence of positive patch test reactions was not found to be influenced by testing during the summer months. image: In the authorsʹ opinion, the prevalence of contact sensitization is generally comparable with the findings of the NACDG, with the exception of reactions to potassium dichromate. This difference in results probably reflects, in part, differences in methodology. The test concentration of potassium dichromate was 0.5%, commonly used in Europe, instead of the 0.25% concentration used by the NACDG. Further investigation is necessary to determine the optimal testing concentration of potassium dichromate.