A novel dynamic risk score to predict venous thromboembolism recurrences after 3 months of anticoagulation in patients with incident venous thromboembolism and without active cancer

BACKGROUND: Predicting recurrent venous thromboembolism (rVTE) risk during and following anticoagulation is complex. Current models do not adapt to changing patient conditions, fail to account for the direct impact of anticoagulation in real-world settings, and are often derived without concurrent major bleeding data. OBJECTIVES: To develop a dynamic, broad, treatment-adjusted, risk score for rVTE. METHODS: Retrospective cohort from UK Clinical Practice Research Datalink (2001-2020) included patients with first VTE who received 3 months of anticoagulation. rVTE risk was modelled using baseline and time-varying covariates (post-VTE). Hazards with 95% confidence intervals (CIs) were estimated, a Fine-Gray model identified predictors. A scoring scheme was developed from subdistribution hazard ratios, with discrimination (C-statistic) estimated via cross-validation. RESULTS: 51,465 patients with VTE were included; 4041 cases of rVTE occurred over 200,698 person-years. rVTE incidence was 2.01 per 100 person-years. The model included 19 predictors, 13 associated with increased risk and 6 with decreased risk. Risk correlated well with outcomes, calibration showed good agreement between predicted and observed risks (calibration slope 0.99 [95% CI, 0.94-1.04]). rVTE risk decreased over 10 years, but within each year higher scores had higher risks (0.92-21.23% in the first year [-5 to +8 points]). The C-statistic, 0.65 (95% CI, 0.64-0.66), was stable over 10 years. CONCLUSIONS: Our dynamic risk score effectively identifies the risk of rVTE after 3 months of treatment and supports ongoing management over 10 years, aiding clinical decision-making on treatment duration and strategy adjustments based on evolving patient characteristics and comorbidities.