This study is the first large-scale epidemiological investigation of acquired aplastic anemia (AAA) in South America. The objective was to estimate the incidence and to identify risk factors for AAA in Brazil. A national case-control study was conducted to investigate the risk factors for the disease. One hundred twenty-five cases and 129 controls were included. Multiple logistic regression was used in the estimation of odds ratios (OR) to control confounding. The size of Brazil made it unfeasible to estimate the incidence of AAA in the whole country, and we limited the calculation to the state of Parana.

The association of agranulocytosis with the use of many different drugs has been documented. LATIN is a case-control study designed to identify risk factors for agranulocytosis and aplastic anemia, including drugs, and to estimate the incidence rates of both diseases in some Latin American countries. This report will cover just agranulocytosis. In 4 years, 52 cases of agranulocytosis were diagnosed. The overall incidence rate was 0.38 cases per 1 million inhabitant-years (0.35 for Brazil, 2.09 for Argentina, and no case verified in Monterrey, Mexico). Agranulocytosis patients more often took medications already associated with agranulocytosis than controls (76.7% of cases and 52.5% of controls; OR 3.7, 95% CI 1.3–12.5; p = 0.01), the most important being methimazole (OR 44.2, 95% CI 6.8 to infinite). The population attributable risk percent (etiologic fraction) was 56%. The use of nutrients supplements was more frequent among agranulocytosis patients than controls (p = 0.03). The agranulocytosis incidence in Latin America was lower than that of European countries and Israel. The rarity of the disease indicates that it is not a public health problem, and there is no reason for major protection measures other than improving diagnostic tools and making earlier agranulocytosis diagnosis.