Underutilization of Warfarin in Older Persons with Chronic Nonvalvular Atrial Fibrillation at High Risk for Developing Stroke

OBJECTIVE: To investigate the prevalence of the use of warfarin to maintain an international normalized ratio (INR) between 2.0 and 3.0 in older persons with chronic nonvalvular atrial fibrillation (AF), and without contraindications to warfarin, who are at high risk for developing new thromboembolic (TE) stroke. DESIGN: A retrospective analysis of charts from all older persons seen during 1997 at an academic hospital-based geriatrics practice. SETTING: An academic hospital-based geriatrics practice staffed by fellows in a geriatrics training program and full-time faculty geriatricians. PATIENTS: Three hundred eighty men and 1183 women, mean age 80+/-8 years (range 59 to 103 years), were included in the study. MEASUREMENTS AND MAIN RESULTS: Of 1563 persons studied, 141 (9%) had chronic nonvalvular AF. Of 141 persons with AF, 127 (90%) were at high risk for developing TE stroke because they had either a previous thromboembolism, congestive heart failure, or echocardiographic evidence of abnormal left ventricular systolic function; a systolic blood pressure >160 mm Hg; or they were women older than 75 years of age. Of the 127 persons with AF at high risk for developing TE stroke, three (2%) had contraindications to warfarin. Of the 124 persons with AF at high risk for developing TE stroke and no contraindications to warfarin, 61 (49%) were treated with warfarin to maintain an INR between 2.0 and 3.0, and 45 (36%) were treated with 325 mg aspirin daily. Of 14 persons with AF at low risk for developing TE stroke, one (7%) was treated with warfarin to maintain an INR between 2.0 and 3.0, and six (43%) were treated with 325 mg aspirin daily. CONCLUSIONS: Warfarin is underutilized as a treatment to maintain an INR between 2.0 and 3.0 in older persons with chronic nonvalvular AF at high risk for developing TE stroke.