Failure to prescribe warfarin to patients with nonrheumatic atrial fibrillation.

OBJECTIVE: To determine how often warfarin was prescribed to patients with nonrheumatic atrial fibrillation in our community in 1992 when randomized trials had demonstrated that warfarin could prevent stroke with little increase in the rate of hemorrhage, and to determine whether warfarin was prescribed less frequently to older patients-the patients at highest risk of stroke but of most concern to physicians in terms of the safety of warfarin. DESIGN: Cross-sectional study. Appropriateness of warfarin was classified for each patient based on the independent judgments of three physicians applying relevant evidence and guidelines. SETTING: Two teaching hospitals and five community-based practices. PATIENTS: Consecutive patients with nonrheumatic atrial fibrillation (n = 189). MEASUREMENTS AND MAIN RESULTS: Warfarin was prescribed to 44 (23%) of the 189 patients. Warfarin was judged appropriate in 98 patients (52%), of whom 36 (37%) were prescribed warfarin. Warfarin was prescribed to 11 (14%) of 76 patients aged 75 years or older with hypertension, diabetes mellitus, or past stroke, the group at highest risk of stroke. In a multivariable logistic regression model controlling for appropriateness of warfarin and other patient characteristics, patients aged 75 years or older were less likely than younger patients to be treated with warfarin (odds ratio 0.25; 95% confidence interval 0.10, 0.65). CONCLUSIONS: Warfarin was prescribed infrequently to these patients with nonrheumatic atrial fibrillation, especially the older patients and even the patients for whom warfarin was judged appropriate. These findings indicate a substantial opportunity to prevent stroke.

Why isn't warfarin prescribed to patients with nonrheumatic atrial fibrillation?

OBJECTIVE: To determine the opinions of selected physicians in our community about use of warfarin for patients with nonrheumatic atrial fibrillation, and to determine the relation of the physicians' opinions to their practices. DESIGN: Survey of physicians, using eight hypothetical clinical vignettes to characterize physicians' opinions about use of warfarin in patients with nonrheumatic atrial fibrillation, according to patient age, risk of bleeding, and risk of stroke. SETTING: Two teaching hospitals and five community-based practices. PARTICIPANTS: Eighty physicians who cared for 189 consecutive patients with nonrheumatic atrial fibrillation. MEASUREMENTS AND MAIN RESULTS: The survey response rate was 73%. Nearly all responding physicians (90%) recommended warfarin for at least one vignette. However, physicians recommended warfarin less often for vignettes depicting 85-year-old patients than for matched vignettes depicting 65-year-old patients (odds ratio [OR] 0.03; 95% confidence interval [CI] 0.01, 0.08), and less often for cases with specified risk factors for bleeding than for matched cases without the risk factors (OR 0.01; 95% CI 0.004, 0.03); warfarin was recommended more often for cases with a recent stroke than for matched cases without this history (OR 8.2; 95% CI 3.6, 18). In practice, warfarin was prescribed more often (p < or = .05) by physicians reporting good personal experience and by those who had favorable opinions about its use. However, even physicians with good experience and favorable opinions did not prescribe warfarin to half of their patents for whom warfarin was independently judged appropriate. CONCLUSIONS: Physicians' opinions frequently opposed warfarin for older patients with nonrheumatic atrial fibrillation, and for those with bleeding risk factors. Physicians' opinions, as well as other barriers to warfarin therapy, most likely contribute to its infrequent prescription.