Management of venous thromboembolism during thrombocytopenia after autologous hematopoietic cell transplantation.

Management of venous thromboembolism (VTE) remains challenging in patients with hematologic malignancy who undergo hematopoietic cell transplantation (HCT) due to prolonged thrombocytopenia. This study aims to (1) determine the incidence of VTE recurrence and bleeding during autologous HCT, (2) assess the impact of continuing vs temporarily withholding anticoagulation during thrombocytopenia, and (3) explore the impact of platelet threshold among other variables on the risk of bleeding. We performed this observational study in adults with lymphoma and myeloma who underwent autologous HCT between 2006 and 2015. We selected patients with index VTE prior to HCT and assigned them to different cohorts based on antithrombotic management at the onset of thrombocytopenia. Primary outcomes included VTE recurrence and major bleeding by 30 days after HCT. Secondary outcomes included platelet and red blood cell transfusions, time to engraftment, and overall survival. Of the 1631 patients who underwent autologous HCT, 204 patients (12.5%) had preceding index VTE events, and among them, 132 patients continued and 72 patients temporarily withheld anticoagulation during thrombocytopenia. There were no significant differences in VTE recurrence (1.5% vs 1.4%) or major bleeding (3.8% vs 4.2%) between 2 groups by 30 days. The number of platelet transfusions was significantly higher in the first group. Baseline elevated bilirubin, creatinine, and prothrombin time were independently associated with increased risk in major bleeding, whereas neither platelet threshold nor average platelet count was predictive. Our findings suggest that for many patients undergoing autologous HCT, temporarily withholding anticoagulation during thrombocytopenia may offer the best risk-benefit tradeoff among available options.