Abstract 13411: Outcomes Associated With Warfarin Time in Therapeutic Range among Veterans With Nonvalvular Atrial Fibrillation in the US, 2005-2015

Introduction: This study evaluated the relationship between quality of warfarin control and clinical outcomes among US veterans with nonvalvular atrial fibrillation (NVAF). Hypothesis: Poor quality of warfarin control (time in therapeutic range (TTR) <65%) is associated with reduced effectiveness and safety. Methods: Using the US Veterans Affairs electronic medical records database, patients with NVAF who newly initiated warfarin from 1/1/2005-12/31/2015 were grouped into two cohorts based on TTR <65% or ≥65%. TTR was computed from international normalized ratio test results comprehensively recorded in the database. Clinical outcomes assessed in the study were stroke/systemic embolism (SE), hemorrhagic stroke, ischemic stroke, and major bleeding, defined based on hospitalization with those conditions as primary diagnosis, as well as all-cause mortality. Patients were followed from warfarin initiation to the first occurrence of an outcome or censoring. For each outcome, unadjusted and adjusted hazard ratio...