Warfarin Use Among Patients With Atrial Fibrillation

Brass, Lawrence M. MD
Krumholz, Harlan M. MD
Scinto, Jeanne M. PhD, MPH
Radford, Martha MD

Received May 16, 1997; final revision received September 8, 1997; accepted September 8, 1997.
From the Center for Outcomes Research and Evaluation, Yale-New Haven Hospital, New Haven, Conn (L.M.B., H.M.K.); Neurology Service, VA Connecticut Healthcare System, West Haven (L.M.B.); Yale Stroke Program, Department of Neurology (L.M.B.), Section of Chronic Disease Epidemiology, School of Epidemiology and Public Health (L.M.B., H.M.K.), and Department of Cardiology (H.M.K.), Yale University School of Medicine, New Haven, Conn; Connecticut Peer Review Organization, Middletown (L.M.B., H.M.K., J.M.S., M.R.); and Department of Cardiology (M.R.), University of Connecticut Health Sciences Center, Farmington.
Presented in part at the 69th Scientific Sessions of the American Heart Association, New Orleans, La, November 10-13, 1996.
Correspondence to Lawrence M. Brass, MD, Yale Stroke Program, Department of Neurology, LCI-700, Yale University School of Medicine, 15 York St, PO Box 208018, New Haven, CT 06520-8018. E-mail [email protected].

Stroke 28(12):p 2382-2389, December 1997.

Background and Purpose

Warfarin reduces the rate of stroke among patients with atrial fibrillation. We sought to determine warfarin use within a population sample of elderly patients with atrial fibrillation.

Methods

The Connecticut Peer Review Organization conducted a chart review of Medicare patients aged >or=to65 years with a history of atrial fibrillation before a hospitalization during the first 6 months of 1994.

Results

Among 488 patients (308 women; 457 white; 173 aged >or=to85 years), 38% (184/488) had a relative contraindication to anticoagulation (history of bleeding, dementia, alcohol use, falls, cancer, or the need for nonsteroidal anti-inflammatory drugs). Among the remaining patients (with known atrial fibrillation, but without a contraindication), only 38% (117/304) had been prescribed warfarin. Of those not prescribed warfarin, 63% (117/187) were also not taking aspirin. There were 272 patients with at least one additional vascular risk factor and no contraindication to anticoagulation. Among these patients at moderate to high risk for stroke, anticoagulation had been prescribed in 40% (109/272). Overall, among those not prescribed warfarin, 58% (95/163) were not taking aspirin. Patients admitted with a stroke were more likely to be significantly underanticoagulated (with international normalized ratio <1.5) (43.5% versus 20.9% for those without stroke; P<.005). Anticoagulation was most effective for those with an international normalized ratio >or=to2.0.

Conclusions

Warfarin anticoagulation with atrial fibrillation, even among "ideal" candidates, appears dramatically underutilized. In addition, among those prescribed warfarin, patients are often undertreated. Increased warfarin use among patients with atrial fibrillation represents an excellent opportunity for stroke prevention in the elderly. (Stroke. 1997;28:2382-2389.)