Laboratory predictors of bleeding and the effect of platelet and RBC transfusions on bleeding outcomes in the PLADO trial.

Bleeding remains a significant problem for many thrombocytopenic hematology/oncology patients in spite of platelet transfusions. Factors that might contribute to bleeding were analyzed for 16 320 patient-days on or after their first platelet transfusion in 1077 adult patients enrolled in the Platelet Dose (PLADO) trial. All patients had a greatly increased risk of bleeding at platelet counts of ≤5 × 10/L (odds ratio [OR], 3.1; 95% confidence interval [CI], 2.0-4.8) compared with platelet counts ≥81 × 10/L. Platelet counts between 6 × 10/L and 80  × 10/L were also associated with a somewhat elevated bleeding risk in patients receiving allogeneic stem cell transplants (SCTs) or chemotherapy but not in those undergoing autologous SCTs. Other significant laboratory predictors of bleeding were hematocrit ≤25% (OR, 1.29; 95% CI, 1.11-1.49), activated partial thromboplastin time (aPTT) 30 to ≤50 seconds (OR, 1.40; 95% CI, 1.08-1.81; = .01), aPTT >50 seconds (OR, 2.34; 95% CI, 1.54-3.56), international normalized ratio (INR) 1.2 to 1.5 (OR, 1.46; 95% CI, 1.17-1.83), and INR >1.5 (OR, 2.05; 95% CI, 1.43-2.95). Transfusion of either platelets or red blood cells (RBCs) on days with bleeding was often not sufficient to change bleeding outcomes on the following day. Because bleeding occurred over a wide range of platelet counts among patients undergoing allogeneic SCT or chemotherapy and because platelet transfusions may not prevent bleeding, other risk factors may be involved. These may include low hematocrit and coagulation abnormalities. This trial was registered at www.clinicaltrials.gov as #NCT00128713.