Factors Associated with Venous Thromboembolism Pharmacoprophylaxis Initiation in Hospitalized Medical Patients: The Medical Inpatients Thrombosis and Hemostasis (MITH) 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.

OBJECTIVE: To determine factors associated with HA-VTE pharmacoprophylaxis initiation in adults hospitalized on medical services.

DESIGN: Cohort study using electronic health record data from adult patients hospitalized on medical services at four academic medical centers between 2016 and 2019.

PARTICIPANTS: 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.

MAIN MEASURES: Candidate predictors of HA-VTE pharmacoprophylaxis initiation, including known HA-VTE risk factors, predicted HA-VTE risk, and bleeding diagnoses present on admission.

KEY RESULTS: 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 two tertiles of predicted HA-VTE risk were less likely to receive HA-VTE pharmacoprophylaxis than patients in the lowest (1st ) tertile (OR 0.84, 95% CI [0.81, 0.86] for 2nd tertile, OR 0.95, 95% CI [0.92, 0.98] for 3rd tertile).

CONCLUSIONS: Among patients not already receiving anticoagulants, HA-VTE pharmacoprophylaxis initiation during the first two hospital days was lower in patients with higher predicted HA-VTE risk and those with risk factors for bleeding. Reasons for not initiating pharmacoprophylaxis in those with higher predicted risk could not be assessed.