Factors associated with venous thromboembolism pharmacoprophylaxis initiation in hospitalized medical patients: the Medical Inpatients Thrombosis and Hemostasis study

Background: Although guidelines recommend risk assessment for hospital-acquired venous thromboembolism (HA-VTE) to inform prophylaxis decisions, studies demonstrate inappropriate utilization of pharmacoprophylaxis in hospitalized medical patients. Predictors of pharmacoprophylaxis initiation in medical inpatients remain largely unknown. Objectives: To determine factors associated with HA-VTE pharmacoprophylaxis initiation in adults hospitalized on medical services. Methods: We performed a cohort study using electronic health record data from adult patients hospitalized on medical services at 4 academic medical centers between 2016 and 2019. Main measures were candidate predictors of HA-VTE pharmacoprophylaxis initiation, including known HA-VTE risk factors, predicted HA-VTE risk, and bleeding diagnoses present on admission. Results: Among 111 550 admissions not on intermediate or full-dose anticoagulation, 48 520 (43.5%) received HA-VTE pharmacoprophylaxis on the day of or the day after admission. After adjustment for age, sex, race/ethnicity, and study site, the strongest clinical predictors of HA-VTE pharmacoprophylaxis initiation were malnutrition and chronic obstructive pulmonary disease. Thrombocytopenia and history of gastrointestinal bleeding were associated with decreased odds of HA-VTE pharmacoprophylaxis initiation. Patients in the highest 2 tertiles of predicted HA-VTE risk were less likely to receive HA-VTE pharmacoprophylaxis than patients in the lowest (first) tertile (OR, 0.84; 95% CI, 0.81-0.86 for the second tertile; OR, 0.95; 95% CI, 0.92-0.98 for the third tertile). Conclusion: Among patients not already receiving anticoagulants, HA-VTE pharmacoprophylaxis initiation during the first 2 hospital days was lower in patients with a higher predicted HA-VTE risk and those with risk factors for bleeding. Reasons for not initiating pharmacoprophylaxis in those with a higher predicted HA-VTE risk could not be assessed.