Outcomes in Older Patients After Switching to a Newer Anticoagulant or Remaining on Warfarin: The COMBINE-AF Substudy.

BACKGROUND: Whether frail, elderly patients with atrial fibrillation (AF) on a vitamin K antagonist (VKA) should switch to a direct-acting oral anticoagulant (DOAC) was studied in the FRAIL-AF trial and remains controversial. OBJECTIVES: The purpose of this study was to evaluate, in the COMBINE-AF data set, the impact on clinical outcomes of switching frail, elderly AF patients from VKA to DOAC. METHODS: COMBINE-AF consists of individual patient-level data from 71,683 patients with AF in 4 randomized clinical trials comparing DOAC vs warfarin. Frailty was evaluated using a frailty index derived from a modified Rockwood's Accumulation Model including 18 age-related conditions. Patients with a frailty index score above the median were considered frail. Prespecified outcomes were stroke or systemic embolic events, bleeding events, death, and a net clinical outcome combining these events. RESULTS: We identified 5,913 patients who were frail, elderly (age ≥75 years), and VKA-experienced and 52,721 patients who did not meet all 3 of these criteria. Patients were randomized to a standard-dose (SD) DOAC or warfarin. After 27 months median follow-up, there was no heterogeneity in treatment effect with SD-DOAC vs warfarin among those who met all 3 criteria vs those who did not for the endpoints of stroke or systemic embolic events (HR: 0.83 vs 0.81; Pint = 0.75) or for death (HR: 0.95 vs 0.91; Pint = 0.54). Major bleeding was similar with SD-DOAC vs warfarin in frail, elderly, VKA-experienced patients (HR: 1.06 [95% CI: 0.90-1.25]), while it was significantly reduced with SD-DOAC in patients without all 3 criteria (HR: 0.82 [95% CI: 0.76-0.89]; Pint = 0.007). Likewise, the net clinical outcome was similar in the frail, elderly, VKA-experienced patients with SD-DOAC vs warfarin (HR: 1.01 [95% CI: 0.91-1.13]), while significantly reduced with SD-DOAC patients without all 3 criteria (HR: 0.89 [95% CI: 0.85-0.93]; Pint = 0.028). Fatal and intracranial bleeding were significantly reduced with SD-DOAC in both subgroups to a similar degree (both Pint > 0.05), while gastrointestinal bleeding with SD-DOAC was increased to a greater degree in frail, elderly, VKA-experienced patients (HR: 1.83 [95% CI: 1.42-2.36]) compared with those without all 3 criteria (HR: 1.23 [95% CI: 1.09-1.39]; Pint = 0.006). CONCLUSIONS: Frail, elderly, VKA-experienced patients with AF switched to SD-DOAC experienced significant reductions in stroke or systemic embolism, fatal and intracranial bleeding, and death. Gastrointestinal bleeding was increased with SD-DOAC, while major bleeding and the primary net clinical outcome were similar. Based on these findings, SD-DOAC is a reasonable choice for frail, elderly, VKA-experienced patients to reduce stroke and systemic embolism, death, and the most serious types of bleeding.

Duke Scholars

Author Manesh Raman Patel Medicine, Cardiology

Author Christopher Bull Granger Medicine, Cardiology

Author Renato Delascio Lopes Medicine, Cardiology