Late-occurring venous thromboembolism in allogeneic blood or marrow transplant survivors: a BMTSS-HiGHS2 risk model

Allogeneic blood or marrow transplant (BMT) recipients are at risk for venous thromboembolism (VTE) because of high-intensity therapeutic exposures, comorbidities, and a proinflammatory state due to chronic graft-versus-host disease (GVHD). The longterm risk of VTE in allogeneic BMT survivors remains unstudied. Participants were drawn from the Blood or Marrow Transplant Survivor Study (BMTSS), a retrospective cohort study that included patients who underwent transplantation between 1974 and 2014 and survived >= 2 years after BMT. We analyzed the risk of VTE in 1554 2-year survivors of allogeneic BMT compared with 907 siblings. Using backward variable selection guided by minimizing Akaike information criterion, we created a prediction model for risk of late occurring VTE. Allogeneic BMT survivors had a 7.3-fold higher risk of VTE compared with siblings (95% CI, 4.69-11.46; P < .0001). After a median follow-up of 11 years, conditional on surviving the first 2 years after BMT, the cumulative incidence of late-occurring VTE was 2.4% at 5 years, 4.9% at 10 years, and 7.1% at 20 years after BMT. The final model for VTE risk at 2 years post-BMT included History of stroke, chronic GVHD, Hypertension, Sex (male vs female) and Stem cell source (peripheral blood stem cells vs other) (HiGHS2) (corrected C-statistics: 0.73; 95% CI 5 0.67-0.79). This model was able to classify patients at high and low VTE risk (10-year cumulative incidence, 9.3% vs 2.4% respectively; P < .0001). The BMTSS HiGHS2 risk model when applied at 2 years post-BMT can be used to inform targeted prevention strategies for patients at high risk for late-occurring VTE.

Automated summary

Allogeneic blood or marrow transplant (BMT) recipients are at a higher risk for venous thromboembolism (VTE) compared to siblings, with a 7.3-fold increased risk. A prediction model (HiGHS2) including factors like history of stroke, chronic GVHD, hypertension, sex, and stem cell source was developed to classify patients at high and low VTE risk, which can inform targeted prevention strategies for high-risk patients.