Hospitalized patients with atrial fibrillation and a high risk of stroke are not being provided with adequate anticoagulation.

OBJECTIVES: The purpose of this study was to determine both treatment gaps and predictors of warfarin use in atrial fibrillation (AF) patients enrolled in a national multicenter study.

BACKGROUND: The National Anticoagulation Benchmark Outcomes Report (NABOR) is a performance improvement program designed to benchmark anticoagulation prophylaxis, treatment, and outcomes among participating hospitals.

METHODS: A retrospective cohort study of inpatients was performed at 21 teaching, 13 community, and 4 Veterans Administration hospitals in the U.S. Patients with an ICD-9-CM code for AF (427.31) were randomly selected.

RESULTS: Among the 945 patients studied, the mean age was 71.5 (+/- 13.5) years; 43% were >75 years of age, 54.5% were men, and 67% had a history of hypertension. Most (86%) had factors that stratified them as at high risk of stroke, and only 55% of those received warfarin. Neither warfarin nor aspirin were prescribed in 21% of high-risk patients, including 18% of those with a previous stroke, transient ischemic attack, or systemic embolic event. Age >80 years (p = 0.008) and perceived bleeding risk (p = 0.022) were negative predictors of warfarin use. Persistent/permanent AF (p < 0.001) and history of stroke, transient ischemic attack, or systemic embolus (p = 0.014) were positive predictors of warfarin use, whereas high-risk stratification was not.

CONCLUSIONS: This study confirms the under-use of warfarin, but also adds to published reports in several regards. It showed that risk stratification, the guidepost for treatment in international guidelines, had little effect on warfarin use, and that age >80 years and AF classification (permanent/persistent) are factors that influence warfarin use.