Warfarin use and the risk of stroke, bleeding, and mortality in older adults on dialysis with incident atrial fibrillation

Aim: There is conflicting evidence regarding the safety and effectiveness of warfarin for atrial fibrillation (AF) treatment among older end-stage renal disease (ESRD) patients, and differences among subgroups are unclear. Methods: Older dialysis patients who were newly diagnosed with AF (7/2007-12/2011) were identified in the United States Renal Data System. The adjusted hazard ratios (HR) of the outcomes (any stroke, ischaemic stroke, major bleeding, severe gastrointestinal bleeding, and death) by time-varying warfarin use were estimated using Cox regression accounting for the inverse probability of treatment weight. Results: Among 5765 older dialysis patients with incident AF, warfarin was associated with significantly increased risk of major bleeding (HR = 1.50, 95% CI 1.33–1.68), but was not statistically associated with any stroke (HR = 0.92, 95% CI 0.75–1.12), ischaemic stroke (HR = 0.88, 95%CI 0.70–1.11) or gastrointestinal bleeding (HR = 1.03, 95% CI 0.80–1.32). Warfarin use was associated with a reduced risk of mortality (HR = 0.72, 95%CI 0.65–0.80). The association between warfarin and major bleeding differed by sex (male: HR = 1.29; 95%CI 1.08–1.55; female: HR = 1.67; 95%CI 1.44–1.93; P-value for interaction = 0.03). Conclusion: Older ESRD patients with AF who were treated with warfarin had a no difference in stroke risk, lower mortality risk, but increased major bleeding risk. The bleeding risk associated with warfarin was greater among women than men. The risk/benefit ratio of warfarin may be less favourable among older women.