(PA-157) Incidence and Risk Factors of Thromboembolic Events in Chinese Patients with Multiple Myeloma: A Single-Center Retrospective Cohort Study

Patients with multiple myeloma (MM) are at a significantly increased risk of developing thromboembolic events (TEs) compared to the general population, owing to disease-related factors, patient-related factors and treatment-related factors. The incidence of venous thromboembolism (VTE) ranges from 10% to 34% following treatment with immunomodulatory drugs (IMiDs), whereas earlier studies in Chinese patients have reported a lower incidence of 3% to 10%. In contrast, data on arterial thromboembolism (ATE) in MM patients remain limited. Given that TEs may adversely affect both treatment efficacy and overall prognosis, the development of standardized strategies for prevention and management is imperative.

Methods: This retrospective cohort study included 661 MM patients admitted to the Department of Hematology, Peking Union Medical College Hospital, between January 1, 2018, and June 1, 2024. After excluding 80 patients due to incomplete data or ineligibility, 581 patients were included in the final analysis. Demographic information, disease stage, comorbidities, and treatment data were extracted from the Hospital Information System (HIS). Univariate analysis of VTE risk factors was conducted among 550 patients who received systemic therapy (40 with VTE and 510 without VTE).

Results: The cumulative incidence of VTE was 10.8% (63/581), with 6.5% occurring within the first six months after diagnosis. The median time to VTE onset was 2.7 months post-diagnosis (IQR: 0–13.6). The cumulative incidence of ATE was 2.9% (17/581), with 1.4% occurring within the first six months and a median onset time of 6.3 months (IQR: 0.2–20.9). Notably, 76% of VTEs and 82% of ATEs occurred during the newly diagnosed MM (NDMM) phase. Univariate analysis revealed significant associations between VTE occurrence and several factors, including older age (median: 67 years [IQR: 61–71] vs. 62 years [IQR: 55–68]; P < 0.001), absence of thromboprophylaxis (OR = 2.77), Eastern Cooperative Oncology Group (ECOG) performance status ≥3 (OR = 3.03), chronic kidney disease (CKD) (OR = 3.45), history of cardiovascular or cerebrovascular disease (OR = 2.38), personal history of VTE (OR = 10.16), and family history of VTE (OR = 12.89) (all P < 0.05). Thromboprophylaxis use was significantly lower among patients who developed VTE (40.0% vs. 64.9%, P < 0.01). The incidence of VTE was 3.2% in patients receiving aspirin prophylaxis compared with 11.9% in those without any prophylaxis.

Conclusions: The incidence of VTE among MM patients in this cohort exceeds previous reports from China, likely due to the increased use of IMiD-based regimens combined with corticosteroids. In addition to treatment-related risk factors, patient-related risk factors such as CKD and cardiovascular or cerebrovascular disease significantly contribute to VTE risk, highlighting the need for refinement of existing risk assessment models. Aspirin appears to offer meaningful clinical benefit as a baseline thromboprophylaxis agent.