Multiple myeloma (MM) patients face elevated venous thromboembolism (VTE) risks, particularly with immunomodulatory drugs (IMiDs). In the Myeloma XI trial, 11.8% of IMiD-treated patients developed VTE despite 87.7% receiving thromboprophylaxis at the time of the event (Leclerc et al., 2022). Given this context, risk assessment strategies are crucial for selecting patiets that would benefit for prophylaxis. In a 10-year retrospective cohort of Brazilian patients, IMPEDE-VTE was found accurate for assessing VTE risk during IMiD therapy, but nearly 98% of the cohort received thalidomide-based regimens (da Costa et al., 2023).

This study evaluates IMPEDE-VTE's application and documented thrombotic events in a Brazilian lenalidomide-treated MM cohort.

We conducted a prospective analysis of all first-line MM patients at a private cancer center between February 2024 and July 2025. A clinical pharmacist calculated IMPEDE-VTE at treatment initiation, and proceeded with interventions with the prescriber for implementation or adjustment of prophylactic therapies if necessary, per institutional protocol. Although IMPEDE-VTE was not designed to measure specific myeloma-driven thrombosis, as it considers IMiD use and VTE prophylaxis on its calculus, a score disregarding the newly prescribed medications was also obtained to explore correlations with pre-treatment thrombotic events. Statistical analysis employed Pearson's χ2 tests for categorical variables and Welch's t-tests for continuous variables (α=0.05).

Sixty patients (mean age 71.8 years) were included in this preliminary analysis. The median follow-up duration was 26.42. Most patients were treated with VRd (80.0%), followed by IsaVRd (10.0%), DRd (3.3%), Rd (3.3%), and DVRd (3.3%). Following treatment, 45.0% of patients were classified as intermediate, 43.3% as low (due to proper use of prophylaxis) and 11.7% as high risk. In total, 3 patients (5.0%) presented thrombotic events during active treatment (grade 2-5). Five other events were documented <90 days prior to treatment initiation (8.3%). A total of 20 pharmaceutical interventions were performed. Of these, 12 interventions were accepted by prescribers (60%), extending the adherence to recommended prophylaxis from 66.7% to 86.7% of the population. Most patients received ASA 100 mg (38.3%) or rivaroxaban 10 mg (28.3%). 13.3% of patients received no VTE prophylaxis. There was a significant association (χ2 = 6.91, p = 0.032) between pre-treatment IMPEDE risk category and the occurrence of pre- treatment thrombosis, but not for the post-treatment risk category (χ2 = 1.35, p = 0.509).

In 18 months, pharmacist-led interventions optimized prophylaxis adherence amongst the hematology team. Yet, 13.3% of patients remained unprotected, underscoring persistent gaps in implementation. VTE incidence is consistent with literature data on this population, but further follow up is needed due to the small sample size.