OC 36.4 - External validation of the IMPEDE VTE score for predicting venous thromboembolism in patients with newly diagnosed multiple myeloma receiving immunomodulatory drugs: a retrospective cohort study

Background: Patients with newly diagnosed multiple myeloma (nMM) receiving immunomodulatory drugs (IMiD) are at high risk for venous thromboembolism (VTE). The IMPEDE VTE score is a risk assessment model (RAM) for VTE risk stratification in patients with nMM initiating IMiD which has been recently incorporated into the National Comprehensive Cancer Network (NCCN) guidelines.

Aims: To validate the IMPEDE VTE score in an external cohort of patients with nMM initiating IMiD.

Methods: Retrospective analysis of a single-center cohort of patients initiating IMiD (2019-2021) at Saint-Louis hospital. The IMPEDE VTE score was calculated as previously described. Patients with IMPEDE VTE scores of ≤3, 4–7, and ≥8 were considered to have low, intermediate, and high risk for VTE within 6 months of IMiD initiation. The Fine & Gray competing risk model, considering death as a competing risk, was used to estimate the cumulative incidences of VTE in the IMPEDE VTE score groups, with their corresponding 95% CI. The IMPEDE VTE score discriminatory performance for predicting VTE at 6-month follow-up was assessed by calculating the Area Under the Receiver Operating Characteristic curve (AUROC, Efron C-index).

Results: We reviewed the electronic medical records of 161 patients with nMM; 156 patients were included in the final analysis. At treatment initiation, 8 (5.1%), 77 (49.4%), and 71 (45.5%) patients had IMPEDE VTE scores of ≤3 (low risk), 4–7 (intermediate risk) and ≥8 (high risk). The 6-month cumulative incidence of VTE was 0% in the low risk group, compared to 2.81% (95% CI 0.74-10.72%) and 4.35% (95% CI 1.44-13.17%) in the intermediate and high risk groups, respectively. The AUROC of the IMPEDE VTE score in identifying patients with nMM who developed VTE was 0.61 (95%CI 0.53-0.69).

Conclusion(s): Our results suggest that the IMPEDE VTE score is an accurate RAM for VTE stratification in patients initiating IMiD-containing regimens.