Patterns and outcomes of prescribing venous thromboembolism prophylaxis in hospitalized older adults: a retrospective cohort study

Venous thromboembolism (VTE) is a major cause of morbidity and mortality in the United States. Hospitalized, medically ill older adults have increased risk; despite guidelines, data suggest suboptimal pharmacologic prophylaxis rates. Factors influencing provider prescribing non-compliance are unclear. We aimed to describe VTE prophylaxis practices and identify risk factors for, and outcomes of, prescribing non-compliance. A retrospective study was conducted of hospitalized adults aged ≥ 75 years, admitted to the medicine service of a large academic tertiary center from May 1, 2014 to June 30, 2015. The primary outcome was non-compliance, defined as the absence of an order for VTE prophylaxis for the duration of hospitalization or an interruption of prophylaxis exceeding 24 h. Secondary measures included in-hospital mortality, length of stay (LOS), and 30-day readmissions. Of 3751 patients (mean age 84.7 years), 97.6% of charts had prophylaxis orders; 11.0% showed non-compliance. Pharmacologic prophylaxis was prescribed in 83.3% of patients and mechanical prophylaxis alone in 14.3%. Factors associated with non-compliance included: higher body mass index (BMI) (p = 0.04), myocardial infarction (p = 0.01), congestive heart failure (p = 0.001), metastatic tumor (p = 0.01). Low mobility was not significantly associated with compliance. Subcutaneous unfractionated heparin was associated with compliance (p < 0.0001); warfarin (p < 0.0001), heparin infusion (p < 0.0001) and low-molecular-weight heparin (p < 0.0001) with non-compliance. Non-compliance was associated with increased mortality (p = 0.01), LOS (p < 0.0001), readmissions (p = 0.0004). Known VTE risk factors (mobility, BMI, comorbidities) were not associated with prescriber compliance patterns. Integrating risk assessment models into provider practice may improve compliance.