Hospital Performance for Pharmacologic Venous Thromboembolism Prophylaxis and Rate of Venous Thromboembolism: A Cohort Study

Study Questions:

What is the association between pharmacologic venous thromboembolism (VTE) prophylaxis rates and hospital-associated VTE?


A retrospective, multicenter cohort study was conducted at 35 hospitals in Michigan between January 2011 and September 2012. Charts from 31,260 general medicine patients were explored for VTE prophylaxis use at admission, VTE risk factors, and VTE events within 90 days following hospital admission. Patients were excluded from analysis if they were receiving systemic anticoagulation, had a contraindication to pharmacologic prophylaxis, or were at low risk for VTE (Caprini score <2). Hospitals were grouped into tertiles of performance based on use of pharmacologic prophylaxis at admission.


A total of 14,563 of 20,794 (70.0%) of eligible general medicine patients received pharmacologic VTE prophylaxis on hospital admission. Pharmacologic prophylaxis for VTE was used in 85.8%, 72.6%, and 55.5% of hospitals in the high-, middle-, and low-performance tertiles. Central venous catheter use during admission occurred in 10.9-12.6% of patients across the three tertiles. A history of malignancy was present in 19.1-22.3% of patients across the three tertiles. Mechanical prophylaxis was ordered on 20.6%, 36.2%, and 32.9% of patients in the high-, middle-, and low-performance tertiles. A total of 226 VTE events occurred within 90 days of admission over 1,765,449 days of patient follow-up. Compared to high-performance hospitals, VTE risk was not different in middle-performance (hazard ratio [HR], 1.10; 95% confidence interval [CI], 0.74-1.62) or low-performance (HR, 0.96; 95% CI, 0.63-1.45) tertiles after adjusting for potential confounders. These findings did not change based on adjustment for mechanical prophylaxis, adherence to prophylaxis during the hospitalization, or re-admission within 90 days of the index hospitalization. Major bleeding occurred in 0.26-0.32% of all patients across the three tertiles.


The authors concluded that VTE risk in hospitalized general medicine patients is low and does not appear to be closely associated with hospital-wide pharmacologic VTE prophylaxis utilization. Based on their findings, the authors question the effectiveness of efforts guided at increasing pharmacologic VTE prophylaxis utilization in hospitalized medical patients.


This large, multicenter, hospital-based cohort study sheds important light into the practice patterns and real-world outcomes associated with pharmacologic VTE prophylaxis in hospitalized medical patients. While there is little doubt that hospitalized surgical patients are at substantial risk for VTE, there have been conflicting reports as to the risk for generalized medical patients. Prior studies demonstrating benefit of pharmacologic VTE prophylaxis have often included surgical patients, patients in the intensive care units (ICU), and patients with malignancy. Those patients are at inherently higher baseline risk of VTE than the general medicine hospitalized patient without cancer. In this study, surgical and ICU patients were excluded, but a significant percentage of the cohort had a history of malignancy. Additionally, unlike some prior studies, this analysis relied on symptomatic VTE as the primary outcome, which is likely to be more clinically relevant than VTE identified on routine imaging of all patients. This study highlights the importance of baseline risk assessment before implementation of population-wide therapeutic strategies. Based on these results, policy makers may reconsider the utility of a strategy to encourage pharmacologic VTE prophylaxis among all hospitalized patients and instead consider targeted interventions at patients with higher VTE risk, such as surgical, ICU, and cancer patients.

Clinical Topics: Pulmonary Hypertension and Venous Thromboembolism, Vascular Medicine

Keywords: Michigan, Intensive Care Units, Neoplasms, Central Venous Catheters, Venous Thromboembolism, Venous Thrombosis, Risk Factors, Risk Assessment, Hospitalization

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