A Retrospective Study of Current Anticoagulant Use in Patients with Atrial Fibrillation: Results from a Managed Care Database.

The vitamin K antagonist warfarin is currently the mainstay of anticoagulant therapy for patients with atrial fibrillation (AF), in whom it has been shown to be effective in preventing stroke. However, it is underused because, despite the quality of clinical care, warfarin can be a difficult drug to manage well. When initiating therapy, patients may require several visits to a coagulation clinic to achieve an international normalized ratio (INR) within the safe and effective range (INR 2–3). Thereafter, frequent monitoring of patients receiving warfarin may still be required due to intrapatient variability. Despite the benefits, studies have shown that approximately 50% of patients who should receive warfarin are not prescribed it or do not receive it. This study was performed to investigate the use of warfarin in eligible patients with AF, for whom it was indicated. Using the US PharMetrics database from 51 managed care organizations, data entered between January 1997 and April 2004, from 5940 patients (>18 years of age with a diagnosis of AF [ICD 9] for whom warfarin was indicated), were analyzed. Patients were excluded if they were not in the database 30 days before and 120 days after their initial diagnosis of AF. Patients were divided into four distinct cohorts, based on treatment patterns: steady users (at least 3 months of warfarin use); discontinued users (used warfarin for only 3 months); non-users (warfarin use for <30 days); and intermittent users (used warfarin prior to first diagnosis of AF, or had less than two prescriptions). Analysis showed that only 31% (1854) of patients were steady users, whereas 59% (3521) of patients were non-users. Also, 4% (246) and 5% (319) of patients were discontinued users and intermittent users, respectively. In addition to a diagnosis of AF, many patients had significant risk factors for stroke: hypertension (48%); diabetes (23%); congestive heart failure (21%); age 75 or older (19%); history of stroke or transient ischemic attack (7%). However, the study showed that patients prescribed warfarin did not have more risk factors compared with long-term steady warfarin users and warfarin non-users (see table). Overall, this study shows that warfarin is underused, even in patients with significant risk factors for stroke, which highlights the need for new, simpler, oral anticoagulant therapy.