Venous thromboembolism in multiple myeloma is associated with increased mortality

Background: In multiple myeloma, venous thromboembolism (VTE) is common, and treatments for myeloma, such as lenalidomide, increase the risk of thrombosis while improving survival. The association between VTE and survival is not well known. Objectives: To determine the association between VTE and survival in multiple myeloma (MM) while adjusting for known confounders that affect risk of thrombosis and survival, including patient characteristics and treatment in a retrospective cohort of US veterans. Patients/Methods: A cohort of patients with newly diagnosed MM treated within Veterans Health Administration between September 1, 1999, and June 30, 2014, was created to assess the association between VTE and mortality using Cox proportional hazards regression modeling while accounting for known prognostic factors and treatments. Results: The cohort comprised 4446 patients with myeloma, including 2837 patients diagnosed after lenalidomide approval in July 2006. VTE occurred in 327 (7.4%) patients within 1 year and occurred at a median of 77 days (interquartile range, 37-153) after starting therapy for MM. In all patients, VTE was associated with increased mortality at 6 months (adjusted hazard ratio [aHR], 1.67; 95% confidence interval [CI], 1.18-2.37). Patients in the post-lenalidomide cohort with VTE had an increased mortality at both 6 months (aHR, 2.31; 95% CI, 1.52-3.51) and 12 months (aHR, 1.66; 95% CI, 1.19-2.33) after treatment initiation. Discussion: This study shows that VTE during the first 6-12 months of therapy is associated with increased mortality in patients with MM. Studies evaluating thromboprophylaxis in patients at high risk of thrombosis are needed.