Predictive and Associative Models to Identify Hospitalized Medical Patients at Risk for Venous Thromboembolism

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Center for Outcomes Research

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Venous Thromboembolism; Hospitalization


Cardiovascular Diseases | Health Services Research


BACKGROUND: Acutely ill hospitalized medical patients are at risk for venous thromboembolism (VTE). We assessed the incidence of VTE in the observational IMPROVE study, and derived VTE risk-assessment scores at admission and associative VTE scores during hospitalization.

METHODS: Data from 15,156 medical patients were analyzed to determine the cumulative incidence of clinically observed VTE over 3 months after admission. Multiple regression analysis identified factors associated with VTE risk.

RESULTS: Of the 184 patients who developed symptomatic VTE, 76 had pulmonary embolism and 67 lower-extremity DVT. Cumulative VTE incidence was 1.0%; 45% of events occurred post-discharge. Factors independently associated with VTE included: previous VTE; known thrombophilia; cancer; age >60, lower limb paralysis; immobilization >/=7 days; and admission to an intensive/coronary care unit (first four were available at admission). Points were assigned to each factor identified to give a total risk score for each patient. At admission, 67% of patients had a score >/=1. During hospitalization, 31% had a score >/=2; for a score of 2 or 3, observed VTE risk was 1.5% vs 5.7% for a score >/=4. Observed and predicted rates were similar for both models (c statistics 0.65 and 0.69, respectively. During hospitalization, a score >/=2 was associated with higher overall and VTE-related mortality.

CONCLUSIONS: Weighted VTE risk scores derived from four clinical risk factors at hospital admission can predict VTE risk in acutely ill hospitalized medical patients. Scores derived from seven clinical factors during hospitalization may help us further understand symptomatic VTE risk. These scores require external validation.

DOI of Published Version



Chest. 2011 Sep;140(3):706-14. Epub 2011 Mar 24. Link to article on publisher's site

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