Background and objectives: Patients with acute myeloid leukemia are at risk of bleeding. The risk factors for different severities of bleeding are poorly studied.
Design and methods: Data from Rebulla et al. were analyzed in an exploratory analysis using multivariate Cox regression analyses for time-to-first bleed with time-depend- ent covariates reflecting measures of clinical and laboratory variables on the previous day. The relationships of the variables with three bleeding categories were studied: mild bleeding (WHO grades 1 and 2) clinically significant (bleeding grades 2, 3 and 4) and severe (bleeding grades 3 and 4).
Results: Bleeding of any severity occurred in 149 (58.4%) of 255 patients. There were 743 days of bleeding over 7335 patient-days of observation. Risk factors for mild bleeding included increased body temperature and decreased platelet count; the risk was decreased with administration of antifungal medication or platelet transfusion on the previous day. Risk factors for clinically significant bleeding included grade 1 bleeding on the previous day, decreased platelet count and elevated body temperature. Decreased platelet count and mild bleeding on the previous day were risk factors for severe bleeding. Higher hemoglobin values were associated with a delay in the time-to-first clinically significant bleed.
Interpretation and conclusions: These results support clinical guidelines for increasing the platelet transfusion threshold in the presence of fever and support the use of milder bleeding symptoms as an outcome in clinical trials. The suggestion that hemo- globin concentration maybe predictive of bleeding risk supports the hypothesis that this maybe a valuable intervention in anemic thrombocytopenic patients at high risk of bleeding.