Among atrial fibrillation (AF) patients, it is unclear whether the efficacy and safety of direct oral anticoagulants (DOAC) relative to warfarin is consistent across various levels of international normalized ratio (INR) control.
To determine the efficacy and safety of DOAC agents compared to warfarin for patients with various levels of anticoagulation control as reflected by their time in therapeutic range (TTR), we conducted a systematic review and meta-analysis of published randomized controlled trials of DOAC versus (vs.) warfarin which reported outcomes stratified by TTR.
Based on reported center-based TTR (cTTR) ranges, degrees of INR control were categorized into 3 cTTR strata: low (<60%), intermediate (60-66%), and high (>66%). Pooled hazard ratios (HR) and 95% confidence intervals (CI) were determined for stroke or systemic embolism (SSE), major bleeding, and intracranial hemorrhage (ICH).
Across all cTTR strata, DOAC-treated patients had lower risk of SSE vs. warfarin, with a HR of 0.73 (95% CI 0.61-0.88) for the low, 0.76 (95% CI 0.59-0.98) intermediate; and 0.78 (95% CI 0.63-0.96) high cTTR subgroups. Compared to warfarin, DOAC-treated patients had lower risk of major bleeding in the low and intermediate cTTR strata, and similar risk in the highest cTTR stratum (HR 1.00, 95% CI 0.80-1.26). Patients treated with DOAC had lower risk of ICH compared to warfarin (HR 0.55, 95% CI; 0.40-0.74) which was observed across all cTTR strata.
In conclusion, regardless of the degree of INR control, DOAC agents are preferable over warfarin as stroke prevention therapy for patients with AF.