Declining Long-term Risk of Adverse Events after First-time Community-presenting Venous Thromboembolism: The Population-based Worcester VTE Study (1999 to 2009)

INTRODUCTION: Contemporary trends in health-care delivery are shifting the management of venous thromboembolism (VTE) events (deep vein thrombosis [DVT] and/or pulmonary embolism [PE]) from the hospital to the community, which may have implications for its prevention, treatment, and outcomes. MATERIALS AND METHODS: Population-based surveillance study monitoring trends in clinical epidemiology among residents of the Worcester, Massachusetts, metropolitan statistical area (WMSA) diagnosed with an acute VTE in all 12 WMSA hospitals. Patients were followed for up to 3 years after their index event. Total of 2334 WMSA residents diagnosed with first-time community-presenting VTE (occurring in an ambulatory setting or diagnosed within 24 hours of hospitalization) from 1999 through 2009. RESULTS: While PE patients were consistently admitted to the hospital for treatment over time, the proportion diagnosed with DVT-alone admitted to the hospital decreased from 67% in 1999 to 37% in 2009 (p value for trend <0.001). Among hospitalized patients, the mean length of stay decreased from 5.6 to 4.8 days (p value for trend <0.001). Between 1999 and 2009, treatment of VTE shifted from warfarin and unfractionated heparin towards use of low-molecular-weight heparins and newer anticoagulants; also, 3-year cumulative event rates decreased for all-cause mortality (41-26%), major bleeding (12-6%), and recurrent VTE (17-9%). CONCLUSIONS: A decade of change in VTE management was accompanied by improved long-term outcomes. However, rates of adverse events remained fairly high in our population-based surveillance study, implying that new risk-assessment tools to identify individuals at increased risk for developing major adverse outcomes over the long term are needed.