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Background Although warfarin is indicated to prevent ischemic strokes in most patients with atrial fibrillation (AF), evidence supporting its use in hemodialysis is limited. Our aim was to examine outcomes after warfarin initiation, relative to no warfarin use, following incident AF in a large cohort of hemodialysis patients who had comprehensive prescription drug coverage through Medicare Part D. Study Design Retrospective observational cohort study. Setting & Participants Patients in the US Renal Data System undergoing maintenance hemodialysis who were newly diagnosed with AF in 2007-2011, with Medicare Part D coverage, who had no recorded history of warfarin use. Predictor Warfarin initiation, identified by a filled prescription within 30 days of the AF event. Outcomes Death, ischemic stroke, hemorrhagic stroke, severe gastrointestinal bleeding, and composite outcomes. Measurements HRs estimated by applying Cox regression to an inverse probability of treatment-and-censoring-weighted cohort. Results Among 12,284 patients with newly diagnosed AF, 1838 (15%) initiated warfarin within 30 days; however, ~70% discontinued its use within one year. In intention-to-treat analyses, warfarin use was marginally associated with a reduced risk of ischemic stroke (HR, 0.68; 95% CI, 0.47-0.99), but not with any of the other outcomes. In as-treated analyses, warfarin use was associated with reduced mortality (HR, 0.84; 95% CI, 0.73-0.97). Limitations Short observation period, limited number of non-fatal events, limited generalizability of results to more affluent patients. Conclusions In hemodialysis patients with incident AF, warfarin use was marginally associated with a reduced risk of ischemic stroke, and there was a signal towards reduced mortality in as-treated analyses. These results support clinical equipoise regarding the use of warfarin in HD patients and underscore the need for randomized trials to fill this evidence gap.

Evidence-informed decision-making in clinical care and policy in nephrology is undermined by trials that selectively report a large number of heterogeneous outcomes, many of which are not patient-centered. The Standardized Outcomes in Nephrology−Hemodialysis (SONG-HD) Initiative convened an international consensus workshop on November 7, 2015, to discuss the identification and implementation of a potential core outcome set for all trials in hemodialysis. The purpose of this article is to report qualitative analyses of the workshop discussions, describing the key aspects to consider when establishing core outcomes in trials involving patients on hemodialysis. Key stakeholders including eight patients/caregivers and 47 health professionals (nephrologists, policy makers, industry, researchers) attended the workshop. Attendees suggested that identifying core outcomes required equitable stakeholder engagement to ensure relevance across patient populations; flexibility to consider evolving priorities over time; deconstruction of language and meaning for conceptual consistency and clarity; understanding of potential overlap and associations between outcomes; and an assessment of applicability to the range of interventions in hemodialysis. For implementation, they proposed that core outcomes must have simple, inexpensive and validated outcome measures that could be used in clinical care (quality ndicators) and trials (including pragmatic trials), and endorsement by regulatory agencies. Integrating these recommendations may foster acceptance and optimize the uptake and translation of core outcomes in hemodialysis, leading to more informative research, for better treatment, and improved patient outcomes.