Thromboembolism Incidence and Risk Factors in Multiple Myeloma After First Exposure to Immunomodulatory Drug-Based Regimens.

Background: We evaluated time to thromboembolism (TE) and risk factors in multiple myeloma (MM) patients after first exposure to immunomodulatory therapy, stratified by thromboprophylaxis.
Patients and Methods: We retrospectively analyzed adult MM patients who received immunomodulatory therapy with or without dexamethasone between February 2012 and October 2017. Thromboprophylaxis included aspirin, anticoagulants (low-molecular-weight heparin, direct oral anticoagulants, or warfarin), or none. Primary endpoint was time to on-treatment TE by thromboprophylaxis type. Time to TE using death as a competing risk censored at 12 months was used in univariate and multivariable analyses to identify risk factors.
Results: Of 485 evaluable patients, 57% were white and 36% African American; median age was 66. Most received lenalidomide (97.5%) and dexamethasone (90%). Half presented with ≥ 1 comorbidities. Sixty-nine had no documented receipt of prophylaxis, 357 aspirin, and 59 anticoagulation. More patients receiving anticoagulants had ≥ 1 comorbidities compared to aspirin or no-prophylaxis groups (P < .001). There was no difference in 12-month estimated cumulative incidence of TE (7.3%; 95% confidence interval, 5.2-9.9) between thromboprophylaxis groups (none 4.4%, aspirin 8.5%, anticoagulant 3.4%) (P = .24). In multivariable analyses, male sex (hazard ratio, 2.50; 95% confidence interval, 1.21-5.17; P = .014) and presence of any comorbidity (hazard ratio, 2.35; 95% confidence interval, 1.17-4.73; P = .016) were associated with TE incidence; thromboprophylaxis type was not (P = .12).
Conclusion: Male sex and presence of any comorbidity were associated with time to TE. There were no differences in TE incidence between thromboprophylaxis groups despite a higher proportion of those in the anticoagulant group having ≥ 1 comorbidities.
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