Epidemiology of adverse cutaneous drug reactions. A prospective study in hospitalized patients.

BACKGROUND: Drug reactions are commonly present in the skin; however, their frequency in our setting is unknown. METHODS: A 10-month prospective cohort study including all hospitalized patients was designed. Those with adverse cutaneous drug reactions (ACDR) were clinically identified. RESULTS: Thirty five drug reactions (prevalence of 0.7%) were seen among 4785 (2713 females, 2072 males) discharged patients. According to Begaud's imputability criteria, the reactions were most likely attributed to a drug in 4.87%, likely in 41.46% and possible in 53.65%. The most commonly seen dermatoses were morbilliform rash 51.2%, urticaria 12.2% and erythema multiforme 4.9%. Drugs most frequently associated with ACDR were amoxicillin clavulanate (8), amphotericin B (2) and metamizole (4). Expressed as risk by 1000 day-doses (Dd: the risk a patient has of developing an ACDR after receiving 1 day of treatment with the drug): amoxicillin clavulanate Dd 7.7, amphotericin B Dd 4.8 and metamizole Dd 3.7. Immunosuppressed patients were most frequently affected. Notably, patients with systemic lupus erythematosus (SLE) had a 4.68 higher risk (CI 95% 1.794-12.186 p <0.001) of developing an ACDR. AIDS patients showed a risk of 8.68 (CI 95% 2.18-33.19 p <0.001). Non-Hodgkin's lymphoma patients also had an increased risk of developing an ACDR. Six of the 35 identified cases were patients who had been hospitalized due to a severe drug reaction (1.3/1000 patients); one died from complications directly related to the ACDR, representing a 16.6% mortality rate among those admitted for an ACDR and 0.02% among the global mortality. CONCLUSIONS: We have a low prevalence of drug reactions compared to data reported in the literature. Pharmacovigilance with special attention to immunosuppressed SLE or AIDS patients is stressed.