Is warfarin really underused in patients with atrial fibrillation?

CONTEXT: There is agreement that warfarin decreases stroke risk in patients with atrial fibrillation (AF), but prior studies suggest that warfarin is markedly underused, for unclear reasons. OBJECTIVE: To determine if warfarin is underused In the treatment of patien ts with atrial fibrillation. DESIGN: Cross-sectional. SETTING: Tertiary care VA hospital. PATIENTS: All patients with a hospital or outpatient diagnosis of AF betwee n 10/1/95 and 5/31/98. DATA COLLECTION:. One or more physician investigators reviewed pertinent re cords for each patient. When any of the 3 investigators thought warfarin mi ght be indicated, the patient's primary care provider completed a survey re garding why warfarin was not used. RESULTS: Of 1,289 AF patients, 844 (65%) had filled at least 1 warfarin pre scription. Of the 445 remaining, 19 had died, 5 had inadequate medical reco rds, and 54 received warfarin elsewhere, leaving 367 patients. Of these, 16 0 had no documented AF, 53 had only a history of AF, and 49 had only transi ent AF. Of the remaining 105 patients, 17 refused warfarin therapy and 72 h ad documented contraindications to warfarin use including bleeding risk or history, fall risk, alcohol abuse, or other compliance problems. The reason s for not using warfarin among the 16 patients remaining included provider oversight (n = 4) and various reasons suggesting provider knowledge deficit s. CONCLUSION: In contrast to prior studies that suggested that warfarin is ma rkedly underused, we found that few patients with AF and no contraindicatio n to anticoagulation were not receiving warfarin. We believe that differing study methodologies, including the use of physician review and provider su rvey, may explain our markedly different rate of warfarin underutilization, although local institutional factors cannot be excluded. The findings sugg est that primary providers may be far more compliant with the standard of c are for patients with atrial fibrillation than previously believed.