Validation of Risk Assessment Models for Venous Thromboembolism in Cancer Patients Receiving Systemic Therapies

Cancer increases the risk of venous thromboembolism (VTE). To identify patients with cancer at high VTE risk that might benefit from primary thromboprophylaxis, several risk assessment models (RAMs) have been developed. The evolution of anti-cancer therapies, including implementation of targeted- and immunotherapeutic agents, might affect VTE risk and risk prediction. Therefore, we aimed to evaluate the performance of six externally validated RAMs (Khorana score, PROTECHT, CONKO, COMPASS-CAT, CATScore and EHR-CAT) in a prospective observational cohort study of patients with cancer initiating contemporary systemic anti-cancer therapies. Eight-hundred-six patients (49.5% women) with a median age of 61 years (interquartile range [IQR]: 53-69) were included. The most common cancer types were lung (21.8%), breast (10.8%), and pancreatic (10.3%). Anti-cancer therapies initiated at study inclusion included chemotherapy (48.3%), combination of chemotherapy and ICI (16.6%), ICI monotherapy (15.4%), and targeted agents (19.7%). During an observation period of six months, 91 patients were diagnosed with VTE (cumulative incidence 11.2%, 95% confidence interval [CI]: 9.0-13.3). The discriminatory performance of the RAMs varied, with the best c-statistic seen with the CATScore, while the COMPASS-CAT score showed the lowest area under the curve (AUC) value (c-statistics [95% CI]: Khorana score: 0.53 [0.50-0.56], PROTECHT: 0.58 [0.56-0.61], CONKO: 0.54 [0.51-0.57], COMPASS-CAT: 0.50 [0.47-0.53], CATScore: 0.65 [0.62-0.67]) and EHR-CAT: 0.55 [0.52-0.57]. Overall, we observed a poor to modest discriminatory performance of the RAMs in our contemporary cohort of patients with cancer, with the CATScore performing best among all evaluated scores.