title: Time in Therapeutic Range and Outcomes After Warfarin Initiation in Newly Diagnosed Atrial Fibrillation Patients With Renal Dysfunction.
abstract: BACKGROUND
  It is unknown whether renal dysfunction conveys poor anticoagulation control in warfarin-treated patients with atrial fibrillation and whether poor anticoagulation control associates with the risk of adverse outcomes in these patients.
  
  
  RESULTS
  This was an observational study from the Stockholm CREatinine Measurements (SCREAM) cohort including all newly diagnosed atrial fibrillation patients initiating treatment with warfarin (n=7738) in Stockholm, Sweden, between 2006 and 2011. Estimated glomerular filtration rate (eGFR; mL/min per 1.73 m2) was calculated from serum creatinine. Time-in-therapeutic range (TTR) was assessed from international normalized ratio (INR) measurements up to warfarin cessation, adverse event, or end of follow-up (2 years). Adverse events considered a composite of intracranial hemorrhage, ischemic stroke, myocardial infarction, or death. During median 254 days, TTR was 83%, based on median 21 INR measurements per patient. TTR was 70% among patients with eGFR <30, around 10% lower than in those with normal renal function. During observation, adverse events occurred in 4.0% of patients, and those with TTR ≤75% were at higher adverse event risk. This was independent of patient characteristics, comorbidities, number of INR tests, days exposed to warfarin, and, notably, independent of eGFR: adjusted odds ratio (OR) 1.84 (95% CI, 1.41-2.40) for TTR 75% to 60% and adjusted OR 2.09 (1.59-2.74) for TTR <60%. No interaction was observed between eGFR and TTR in association to adverse events (P=0.2).
  
  
  CONCLUSIONS
  Severe chronic kidney disease (eGFR <30) patients with atrial fibrillation have worse INR control while on warfarin. An optimal TTR (>75%) is associated with lower risk of adverse events, independently of underlying renal function.
authors.affiliation: Department of Medicine, Karolinska Institutet, Stockholm, Sweden karolina.szummer@karolinska.se.|Department of Cardiology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Karolina
authors.initials: K
authors.lastname: Szummer
authors.affiliation: Renal Medicine, Departments of Clinical Science, Technology and Intervention (CLINTEC), Stockholm, Sweden.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Gasparini
authors.affiliation: Departments of Nephrology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Staffan
authors.initials: S
authors.lastname: Eliasson
authors.affiliation: School of Health and Social Studies, Dalarna University, Falun, Sweden.|Department of Medical Sciences, Uppsala University Hospital, Uppsala, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Ärnlöv
authors.affiliation: Renal Medicine, Departments of Clinical Science, Technology and Intervention (CLINTEC), Stockholm, Sweden.
authors.forename: Abdul Rashid
authors.initials: AR
authors.lastname: Qureshi
authors.affiliation: Renal Medicine, Departments of Clinical Science, Technology and Intervention (CLINTEC), Stockholm, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Bárány
authors.affiliation: Renal Medicine, Departments of Clinical Science, Technology and Intervention (CLINTEC), Stockholm, Sweden.
authors.forename: Marie
authors.initials: M
authors.lastname: Evans
authors.affiliation: Department of Clinical Sciencies, Danderyds Hospital, Stockholm, Sweden.
authors.forename: Leif
authors.initials: L
authors.lastname: Friberg
authors.affiliation: Renal Medicine, Departments of Clinical Science, Technology and Intervention (CLINTEC), Stockholm, Sweden.|Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Juan Jesus
authors.initials: JJ
authors.lastname: Carrero
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy*; D001777:Blood Coagulation / Q000187:drug effects; D003404:Creatinine / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011379:Prognosis; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000150:complications* / Q000401:mortality; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D020521:Stroke / Q000209:etiology / Q000401:mortality / Q000517:prevention & control*; D015996:Survival Rate / Q000639:trends; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors; D016896:Treatment Outcome; D014859:Warfarin / Q000009:adverse effects* / Q000627:therapeutic use
chemical_list: D000925:Anticoagulants; D014859:Warfarin; D003404:Creatinine
keywords: all‐cause death; anticoagulant; atrial fibrillation; bleeding; ischemic stroke; renal function