An epidemiological study of aplastic anaemia: Relationship of drug exposures to clinical features and outcome

Abstract

Two hypotheses were examined in the combined data from 3 case-control studies of aplastic anaemia, conducted in Thailand, Europe/ Israel and the US: 1. Cases exposed to drugs associated with a significantly increased risk of aplastic anaemia are more likely to present with thrombocytopenia (e.g. petechiae, easy bruising); and 2. cases exposed to these drugs are more likely to recover quickly than non-exposed cases. After excluding all cases who lacked information on timing of symptoms and those whose symptoms began ≤ 180 d before hospital admission, 392 cases remained for analysis. A total of 51 (13%) had been exposed to one of the significantly associated drugs; the remaining 341 (87%) had not. Among the former, 31% reported thrombocytopenia either before or at the same time as non-bleeding symptoms (e.g. pallor, fatigue); the corresponding proportion among the non-exposed was 53%. Data on time to recovery (return of the 3 blood cell lines to normal levels) were not available for the Thai cases; among the others, the median time to recovery for the non-fatal cases was 7 and 6 months in the 29 exposed and the 83 non-exposed cases, respectively The data do not support either hypothesis: the two groups of aplastic anaemia cases appeared to be similar in both the presenting symptoms and the recovery time.