Bleeding Risk from Anticoagulant Thromboprophylaxis in Patients with Multiple Myeloma: A MarketScan Analysis

Background Multiple Myeloma (MM) is associated with high risk of venous thromboembolism (VTE). Anticoagulant prophylaxis is frequently recommended but underutilized partly due to absent studies assessing bleeding risk. Objective To determine the rate of severe (hospitalized) bleeding from thromboprophylaxis in patients treated for MM and identify clinical risk factors for bleeding in this population. Methods Using the MarketScan database, we analyzed 6,656 patients treated for MM between 2013-2021. Concomitant thromboprophylaxis was defined using prescription claims. Hospitalized bleeding was identified through the Cunningham algorithm. Bleeding rates were compared by thromboprophylaxis status and Cox regression identified risk factors for bleeding. Results Anticoagulant thromboprophylaxis was used in 6.6% (436) patients treated for MM. Patients on thromboprophylaxis had a higher rate of immunomodulatory-based therapy (63.8% vs 46.7%, p<0.01) and lower anti-platelet use (2.1% vs 4.7%, p<0.01). Bleeding occurred in 1.4% of them during median follow-up of 1.3 years. Rate of severe bleeding was no different between those on prophylaxis (7.8 per 1,000 person-year) or not (10.1 per 1,000 person-year). No association was identified between thromboprophylaxis and bleeding. Factors associated with increased bleeding included age (HR=1.38 per 10-years older), comorbidity index (HR=1.18 per SD increase), history of bleeding (HR=1.54), hypertension (HR=1.87), and renal disease (HR=1.56). Conclusion Risk of serious bleeding from thromboprophylaxis in patients treated for MM was low and concomitant anticoagulant therapy did not result in increased bleeding risk. Clinical risk factors for bleeding included age, comorbidity index, bleeding history, hypertension, and renal disease.