Epidemiology of aplastic anemia: a prospective multicenter study

Abstract

Aplastic anemia is a rare and severe disease. Its incidence varies considerably worldwide. We aimed at describing the epidemiology of this disease, including the incidence, mortality and survival trends, in a well-defined population. Since 1980, a case-control surveillance study of aplastic anemia has been carried out by a cooperative group, in the metropolitan area of Barcelona. Inclusion is dependent on the patient having at least two of the following features: white blood cell count < or = 3.5 x 10(9)/L, platelet count < or = 50 x 10(9)/L, hemoglobin <10 g/L or hematocrit of <30%; when only one of these last two criteria is fulfilled, a reticulocyte count of < or = 30 x 10(9)/L is also required. The bone marrow biopsy has to be compatible with the diagnosis of aplastic anemia. Between 1980 and 2003, a total of 235 cases of aplastic anemia were identified. The overall incidence was 2.34 per million inhabitants per year and the incidence increased with age. Most of the cases were classified as severe or very severe aplastic anemia. Survival rates at 3 months, and at 2 and 15 years after the diagnosis were 73%, 57%, and 51%, respectively. Advanced age and more severe disease at the time of diagnosis were associated with a lower survival rate. There was a trend to a better 2-year survival rate among patients treated with bone marrow transplantation. Forty-nine cases (20.8%) were exposed to drugs reported to be associated with aplastic anemia, and 21 (8.9%) to toxic agents. The incidence of aplastic anemia in Barcelona is low but the case fatality rate is high. Advanced age and severe disease at the time of diagnosis were associated with decreased survival.