Adverse Outcomes and Predictors of Underuse of Antithrombotic Therapy in Medicare Beneficiaries With Chronic Atrial Fibrillation

Background and Purpose—Antithrombotic therapy can prevent strokes and transient ischemic attacks (TIAs) in carefully selected patients who have chronic nonvalvular atrial fibrillation (NVAF). Our objectives were 3-fold: to document the use of warfarin and aspirin therapy in Missouri Medicare beneficiaries with chronic NVAF; to identify factors associated with warfarin and aspirin underuse; and to determine the association between prescription of warfarin and aspirin at hospital discharge and adverse outcomes in this elderly, frail population. Methods—We linked chart reviews from all Missouri hospitals to Medicare claims data from 1993 to 1996. From chart reviews, we documented Medicare beneficiaries’ demographic factors, comorbid conditions, and antithrombotic therapy prescribed at the time of hospital discharge. From Medicare claims, we determined the date of outcomes—death from any cause or hospitalization for an ischemic event (a stroke, a TIA, or a myocardial infarction). Results—Only 328 (55%) of the...