Background: Medical patients experience increased risk of venous thromboembolism following hospital discharge. Extended duration thromboprophylaxis (EDT) can reduce VTE risk but may carry bleeding risks. Evidence for risks and benefits of EDT remains limited. A recent study used readily available blood count and chemistry labs to derive 90-day risk scores for VTE and bleed outcomes .
Aims: External validation of the Intermountain Risk Score for hospital-associated venous thromboembolism (HA-VTE IMRS) and major bleeding (HA-MB IMRS).
Methods: Retrospective cohort study of adult patients discharged alive from medical services at an academic medical center between 2015-2019. Patients were excluded for known VTE, preexisting anticoagulant use, or recent surgical procedure. HA-VTE IMRS and HA-MB IMRS were calculated and dichotomized as high- or low-risk as described in the derivation manuscript. 90-day post-discharge VTE and bleeding outcomes were assessed using ICD-10 codes and blood bank transfusion records.
Results: 113,578 patients remained in the final analysis. For VTE prediction, 66,340 (58.4%) had a low-risk HA-VTE IMRS < 7, versus 47,238 (41.6%) high-risk ≥7. For bleed prediction, 71,576 (63%) had a low-risk HA-MB IMRS < 8, versus 42,002 (37%) high-risk ≥ 8. VTE incidence was 1.1% in high-risk versus 0.6% in low-risk cohort. Major bleeding incidence was 1.3% in high-risk versus 0.1% in low-risk cohort. AUCs for VTE and bleed outcome discrimination were 0.585 and 0.78, respectively. Patients with a combined high-risk VTE score and low-risk bleeding score comprised 14.5% of the population.
Conclusion(s): In this external validation study, the HA-VTE IMRS did not discriminate well for VTE but the HA-MB IMRS had high discriminatory ability for major bleeding events. A sizable minority of patients were categorized as high VTE risk with low bleed risk, a population which may benefit from EDT. Further prospective research on these risk scores may better define efficacious and safe EDT among medical patients.
To cite this abstract in AMA style:Hyder S, Barnes G, Han H, Ash S, Woller S, Horne B, Stevens S. Predicting post-discharge venous thromboembolism and major bleeding among medical patients: External validation of a risk score derived from readily available laboratory tests. [abstract]. https://abstracts.isth.org/abstract/predicting-post-discharge-venous-thromboembolism-and-major-bleeding-among-medical-patients-external-validation-of-a-risk-score-derived-from-readily-available-laboratory-tests/. Accessed September 29, 2023.
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