Incidence and risk factors for agranulocytosis in Latin American countries - the Latin study

Purpose LATIN is a multinational case-control study designed to identify risk factors for agranulocytosis and to estimate the incidence rate of the disease in some Latin American countries. Methods Each study site in Brazil, Argentina and Mexico conducted an active search of agranulocytosis patients in hematology clinics and looked for possible associations with drug use. Results The overall incidence rate was 0.38 cases per 1 million inhabitant-years. Agranulocytosis patients more often took medications already associated with agranulocytosis than controls (p=0.01), mainly methimazole (OR 44.2, 95% CI 6.8 to infinity). The population attributable risk percentage (etiologic fraction) was 56%. The use of nutrient supplements was more frequent among patients than controls (p=0.03). Conclusions Agranulocytosis seems to be very rare in Latin America. The lower than expected number of cases identified during the study period precluded estimation of the risk associated to individual drugs, with the exception of methimazol. However, this is the longest series of agranulocytosis cases ever gathered in Latin America, and information on drug exposures was collected prospectively. The conclusion is that drug-induced agranulocytosis does not seem to be a major public health problem in the study regions.