Importance Hospitalization for acute medical illness is associated with increased risk of venous thromboembolism (VTE). Although efforts designed to increase use of pharmacologic VTE prophylaxis are intended to reduce hospital-associated VTE, whether higher rates of prophylaxis reduce VTE in medical patients is unknown.
Objective To examine the association between pharmacologic VTE prophylaxis rates and hospital-associated VTE.
Design, Setting, and Participants Retrospective, multicenter cohort study conducted at 35 Michigan hospitals participating in a statewide quality collaborative from January 1, 2011, through September 13, 2012. Trained medical record abstractors at each hospital collected data from 31 260 general medical patients. Use of VTE prophylaxis on admission, VTE risk factors, and VTE events 90 days after hospital admission were recorded using a combination of medical record review and telephone follow-up. Hospitals were grouped into tertiles of performance based on rate of pharmacologic prophylaxis use on admission for at-risk patients.
Main Outcomes and Measures Association between hospital performance and time to development of VTE within 90 days of hospital admission.
Results A total of 14 563 of 20 794 patients (70.0%) eligible for pharmacologic prophylaxis received prophylaxis on admission. The rates of pharmacologic prophylaxis use at hospitals in the high-, moderate-, and low-performance tertiles were 85.8%, 72.6%, and 55.5%, respectively. A total of 226 VTE events occurred during 1 765 449 days of patient follow-up. Compared with patients at hospitals in the highest-performance tertile, the hazard of VTE in patients at hospitals in moderate-performance (hazard ratio, 1.10; 95% CI, 0.74-1.62) and low-performance (hazard ratio, 0.96, 95% CI, 0.63-1.45) tertiles did not differ after adjusting for potential confounders. Results remained robust when examining mechanical prophylaxis, prophylaxis use throughout the hospitalization, and subsequent inpatient stays after discharge from the index hospitalization.
Conclusions and Relevance The occurrence of 90-day VTE in medical patients after hospitalization is low. Patients who receive care at hospitals that have lower rates of pharmacologic prophylaxis do not have higher adjusted hazards of VTE, even after accounting for individual receipt of pharmacologic prophylaxis.
Related commentary from ACP Hospitalist Weekly:
The findings suggest that "efforts to broadly increase rates of pharmacologic prophylaxis in non-critically ill general medical patients may not yield significant reductions in hospital-associated (VTE)," the authors wrote. Some of the past studies that found an association between using prophylaxis and lower VTE rates included patients with higher baseline risk of VTE like surgical patients, and patients with longer average lengths of stay than the typical medical service patient, they wrote. Many VTE experts and toolkits support an approach that would result in up to 95% of inpatients receiving prophylaxis, but "our study questions the wisdom of that approach," they wrote.
Unwise indeed. Moreover, guidelines for VTE prophylaxis in medical patients are sufficiently restrictive that it is unlikely that 95% of patients would be candidates. Performance driven initiatives tend to push the number higher than appropriate, however.