Trial of low doses of aspirin as prophylaxis in sickle cell disease.

The effects of low doses of aspirin on the frequency and severity of painful vaso-occlusive crises were evaluated in children with sickle hemoglobinopathies. Aspirin was compared with placebo in 49 patients in a double-blind crossover study. Careful monitoring of patients revealed an average of 1.1 painful crises per patient year. During the 21 months of study, 70% of patients had a maximum of two painful crises, and 25% experienced four or more. The frequency and severity of crises were not affected by aspirin therapy. In view of aspirin's demonstrated effect on platelet function, we suggest that platelets do not contribute to the initiation or progression of the vaso-occlusive process.