Effect of warfarin on outcomes in septuagenarian patients with atrial fibrillation

Abstract

Anticoagulation has been shown to decrease ischemic stroke in atrial fibrillation (AF). However, concerns remain regarding their safety and efficacy in those ≥70 years of age who constitute most patients with AF. Of the 4,060 patients (mean age 65 years, range 49 to 80) in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial, 2,248 (55% of 4,060) were 70 to 80 years of age, 1,901 of whom were receiving warfarin. Propensity score for warfarin use, estimated for each of the 2,248 patients, was used to match 227 of the 347 patients not on warfarin (in 1:1, 1:2, or 1:3 sets) to 616 patients on warfarin who were balanced in 45 baseline characteristics. All-cause mortality occurred in 18% and 33% of matched patients receiving and not receiving warfarin, respectively, during up to 6 years (mean 3.4) of follow-up (hazard ratio [HR] when warfarin use was compared to its nonuse 0.58, 95% confidence interval [CI] 0.43 to 0.77, p <0.001). All-cause hospitalization occurred in 64% and 67% of matched patients receiving and not receiving warfarin, respectively (HR associated with warfarin use 0.93, 95% CI 0.77 to 1.12, p = 0.423). Ischemic stroke occurred in 4% and 8% of matched patients receiving and not receiving warfarin, respectively (HR associated with warfarin use 0.57, 95% CI 0.31 to 1.04, p = 0.068). Major bleeding occurred in 7% and 10% of matched patients receiving and not receiving warfarin, respectively (HR associated with warfarin use 0.73, 95% CI 0.44 to 1.22, p = 0.229). In conclusion, warfarin use was associated with decreased mortality in septuagenarian patients with AF but had no association with hospitalization or major bleeding.

Figure 1

Absolute standardized differences of 45 baseline characteristics between patients receiving and not receiving warfarin, before and after propensity score matching (*Symptoms experienced during atrial fibrillation in the last six months; **Hospitalization for qualifying episodes of atrial fibrillation; ACE = angiotensin-converting enzyme; HTN = hypertension; NYHA = New York Heart Association; PND = paroxysmal nocturnal dyspnea)

Figure 2

Kaplan-Meier plots for (a) all-cause mortality, and (b) all-cause hospitalization by warfarin use (HR=hazard ratio; CI=confidence interval)

Figure 3

Association of warfarin use with all-cause mortality in subgroups of propensity-matched atrial fibrillation patients 70 years of age (CI=confidence interval)