Heparin versus aspirin thromboprophylaxis adds independent value to IMPEDE-VTE score for venous thrombosis prediction in multiple myeloma

Multiple myeloma (MM) is associated to an increased incidence of venous thromboembolism (VTE). IMPEDE-VTE score constitutes a valuable risk assessment tool for VTE prediction in first-line MM patients. Nevertheless, refinement of the primary thromboprophylaxis category of this score (which pools aspirin and heparin) seems desirable. To investigate the role of the type of thromboprophylaxis, within IMPEDE-VTE score, for VTE prediction in MM patients. Retrospective analysis of a single-center cohort of 438 MM patients receiving first-line antimyeloma treatment (1991–2020). IMPEDE-VTE score was calculated. Primary thromboprophylaxis was additionally stratified into aspirin- and heparin-based regimen subgroups. VTE risk was analyzed by Cox regression. Median follow-up during first-line antimyeloma treatment was 6.0 months (IQR 4.1–9.0 months). Twenty-three patients developed VTE (5.3%, 95%CI 3.4–7.8%). IMPEDE-VTE score showed a notable predictive value (area under the ROC curve: 0.70, 95%CI 0.60–0.80). Cox analysis confirmed that 1-point increase in the score resulted in a 1.3-fold increase in VTE risk (HR 1.30, 95%CI 1.13–1.53, p < 0.001). In the multivariable analysis, the type of primary thromboprophylaxis (heparin versus aspirin) was an independent predictive factor (HR 0.15, 95% CI 0.05–0.47, p = 0.001). The combined model showed a higher goodness-of-fit (Akaike Information Criterion [AIC]: 99) than IMPEDE-VTE separately (AIC:235). Our analysis contributes to the external validation of IMPEDE-VTE score for the prediction of VTE in MM. But more interestingly, our results demonstrate that among those patients receiving thromboprophylaxis, the type of regimen (heparin versus aspirin) adds independent predictive value and should be explored for a more accurate risk assessment.