Warfarin for prevention of thrombosis among long-term care residents with atrial fibrillation: evidence of continuing low use despite consideration of stroke and bleeding risk.

OBJECTIVES: The aims of the study were to evaluate usage rates of warfarin in stroke prophylaxis and the association with assessed stages of stroke and bleeding risk in long-term care (LTC) residents with atrial fibrillation (AFib).

METHODS: A cross-sectional analysis of two LTC databases (the National Nursing Home Survey [NNHS] 2004 and an integrated LTC database: AnalytiCare) was conducted. The study involved LTC facilities across the USA (NNHS) and within 19 states (AnalytiCare). It included LTC residents diagnosed with AFib (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] diagnostic code 427.3X). Consensus guideline algorithms were used to classify residents by stroke risk categories: low (none or 1+ weak stroke risk factors), moderate (1 moderate), high (2+ moderate or 1+ high). Residents were also classified by number of risk factors for bleeding (0-1, 2, 3, 4+). Current use of warfarin was assessed. A logistic regression model predicted odds of warfarin use associated with the stroke and bleeding risk categories.

RESULTS: The NNHS and AnalytiCare databases had 1,454 and 3,757 residents with AFib, respectively. In all, 34 % and 45 % of residents with AFib in each respective database were receiving warfarin. Only 36 % and 45 % of high-stroke-risk residents were receiving warfarin, respectively. In the logistic regression model for the NNHS data, when compared with those residents having none or 1+ weak stroke risk and 0-1 bleeding risk factors, the odds of receiving warfarin increased with stroke risk (odds ratio [OR] = 1.93, p = 0.118 [1 moderate risk factor]; OR = 3.19, p = 0.005 [2+ moderate risk factors]; and OR = 8.18, p ≤ 0.001 [1+ high risk factors]) and decreased with bleeding risk (OR = 0.83, p = 0.366 [2 risk factors]; OR = 0.47, p ≤ 0.001 [3 risk factors]; OR = 0.17, p ≤ 0.001 [4+ risk factors]). A similar directional but more constrained trend was noted for the AnalytiCare data: only 3 and 4+ bleeding risk factors were significant.

CONCLUSIONS: The results from two LTC databases suggest that residents with AFib have a high risk of stroke. Warfarin use increased with greater stroke risk and declined with greater bleeding risk; however, only half of those classified as appropriate warfarin candidates were receiving guideline-recommended anticoagulant prophylaxis.