Clinical Utility and Costs of Inpatient Hereditary Thrombophilia Testing following Acute VTE: A 5-Year Retrospective Study

Background Hereditary thrombophilia testing is frequently ordered after venous thromboembolism (VTE), despite little evidence of clinical utility and most guidelines cautioning against testing. Methods We conducted a retrospective, observational study of inpatient hereditary thrombophilia testing ordered during a hospital admission for acute VTE between 2019 and 2024. We aimed to characterize patterns of testing results, and costs, and to evaluate whether younger patients and those with unprovoked VTE were more likely to test positive for hereditary thrombophilia. Results A total of 835 hereditary thrombophilia tests – including those for factor V Leiden, prothrombin _G20210A , deficiencies of protein S, protein C, and antithrombin, hyperhomocysteinemia, and plasminogen activator inhibitor-1 excess – were ordered in 220 patients. Overall, 19.6% of results were abnormal, and 45.0% of patients had at least one abnormal result. There was no difference in the rate of positive results among patients with provoked vs unprovoked VTE (30.7% vs 34.5%, p = .554) nor patients < 50 vs ≥ 50 years of age (33.1% vs 32.4%, p = .912). Only 4/99 (4.0%) patients with an abnormal result had their clinical management clearly changed due to the result. The tests totaled $385,161 USD in institutional charges and $26,029 USD in Medicare fees. Conclusion Inpatient hereditary thrombophilia testing during admission for acute VTE is low yield, with frequent abnormal results, many of which likely represented false positives, and minimal impact on clinical management with high costs.