LOW DRUG ATTRIBUTABILITY OF APLASTIC-ANEMIA IN THAILAND

From 1989 to 1994, a population-based, case-control study of aplastic anemia was conducted in Thailand, including the regions of Bangkok, Kh onkaen in the northeast, and Songkla in the south. An annual incidence in Bangkok of 3.7 cases per million population, about twice as high a s in Western countries, has been reported. To evaluate the etiologic r ole of drugs, 253 subjects were compared with 1,174 hospital controls. With multivariate adjustment for confounding, a significant associati on was identified for exposure 2 to 6 months before admission to thiaz ide diuretics (relative risk estimate 7.7; 1.5 to 40). There were crud e associations with sulfonamides (relative risk estimate, 7.9; P= 0.00 4) and mebendazole (6.3; P = 0.03) (there were insufficient data for m ultivariate adjustment). Excess risks for the three drugs were in the range of 9 to 12 cases per million users. There was no significant ass ociation with chloramphenicol, although the multivariate relative-risk estimate was elevated (2.7; 0.7 to 10). Other drugs that have been re ported to increase the risk of aplastic anemia, such as nonsteroidal a nti-inflammatory drugs and anticonvulsants, were not commonly used. Th ere were no associations with commonly used drugs, including benzodiaz epines, antihistamines, oral contraceptives, and herbal preparations. For all associated drugs, the overall etiologic fraction (the proporti on of cases attributable to an exposure) was 5%, compared with 25% in Europe and Israel. Drugs are uncommon causes of aplastic anemia in Tha iland, and their use does not explain the relatively high incidence of the disease in that country. (C) 1997 by The American Society of Hema tology.