IS WARFARIN UNDERUSED IN THE TREATMENT OF ELDERLY PERSONS WITH ATRIAL-FIBRILLATION

Background: Several randomized clinical trials have shown that among p atients with atrial fibrillation, warfarin sodium use protects against stroke. Recently, experts have voiced concern about possible underuse of warfarin by practicing physicians. Few studies, however, have quan titated the amount of warfarin underuse. Methods: We randomly sampled 65 Medicare beneficiaries discharged alive from each of 5 small Pennsy lvania hospitals between July 1, 1993, and June 30, 1994, with a disch arge diagnosis code for atrial fibrillation. Trained abstractors verif ied that atrial fibrillation was present at some time during the hospi talization, determined the presence of contraindications to anticoagul ation, and identified warfarin or aspirin use at discharge for each pa tient. An internist used implicit criteria to identify the reason for warfarin nonuse in patients who had none of the explicit contraindicat ions to warfarin and did not receive it. Results: Of 322 charts review ed, 48 patients were not in atrial fibrillation during the hospitaliza tion, 79 had contraindications to warfarin use, 21 either died or were transferred to another hospital, and 2 were admitted with a complicat ion of warfarin. Of the 172 remaining patients, 76 (44%) underwent ant icoagulation. On implicit review of the 96 patients who did not underg o anticoagulation, the internist judged that warfarin would not have b een appropriate in 54. After excluding those patient's, 76 (64%) of th e remaining 118 patients underwent anticoagulation. Patients not recei ving warfarin were slightly older (81.6 vs 78.3 years old), but this w as not statistically significant after stratifying by hospital. Rates of warfarin use at the 5 hospitals varied widely (32%, 57%, 79%, 82%, 94%; P<.001, chi(2) with 4 df). Patients with newly diagnosed atrial f ibrillation were not more likely to undergo anticoagulation, nor were patients treated by internal medicine or cardiology specialists. Concl usions: There may be significant warfarin underuse in some hospitals. Overall, approximately one third of patients with atrial fibrillation for whom it appeared appropriate were not anticoagulated with warfarin . Although the fact that data were not available to or were missed by our review surely justifies some of the underuse, one should recall th at even a small amount of underuse affect a large number of people wit h this common condition.