, Volume 27, Issue 9, pp 623-633
Date: 30 Jul 2010

Warfarin therapy in patients with venous thromboembolism: Patterns of use and predictors of clinical outcomes

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Abstract

Introduction

Few studies have investigated current practices in the USA relating to warfarin use and monitoring, or the effects of warfarin discontinuation on risk of venous thromboembolism (VTE) and bleeding complications. This study investigated the effect of warfarin discontinuation on rates of VTE recurrence in a real-world setting.

Methods

Integrated Healthcare Information Services database records from January 2003 to September 2007 from patients aged at least 18 years, hospitalized for VTE, and with at least two prescriptions or 60 days of warfarin treatment were reviewed, with warfarin discontinuation and international normalized ratio (INR) data collated.

Results

A total of 1027 of 8380 (12.3%) patients discontinued warfarin within 3 months. Overall, 1656 (19.8%) patients had no INR monitoring, with 38.1% of INR values being inside the therapeutic range (INR 2–3). Recurrent VTE was observed in 915 (10.9%) patients. Significant predictors of recurrent VTE (at any time) included discontinuation of warfarin within 3 months, time from index VTE to warfarin initiation, previous VTE-related hospitalization, and duration of index hospitalization.

Conclusion

This study found that in a real-world population, less than 50% of warfarin patients achieved INR values within the therapeutic range. Warfarin discontinuation within 3 months was associated with a higher rate of recurrent VTE.