title: Ischemic Stroke Risk in Patients With Atrial Fibrillation and CHA2DS2-VASc Score of 1: Systematic Review and Meta-Analysis.
abstract: The CHA2DS2-VASc score aims to improve risk stratification of ischemic stroke among patients with atrial fibrillation to identify those who can safely forego oral anticoagulation. Oral anticoagulation treatment guidelines remain uncertain for CHA2DS2-VASc score of 1. We conducted a systematic review and meta-analysis of the risk of ischemic stroke for patients with atrial fibrillation and CHA2DS2-VASc score of 0, 1, or 2 not treated with oral anticoagulation.
  
  
  
  We searched MEDLINE, Embase, PubMed, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Web of Science from the start of the database up until April 15, 2015. We included studies that stratified the risk of ischemic stroke by CHA2DS2-VASc score for patients with nonvalvular atrial fibrillation. We estimated the summary annual rate of ischemic stroke using random effects meta-analyses and compared the estimated stroke rates with published net-benefit thresholds for initiating anticoagulants.
  
  
  
  1162 abstracts were retrieved, of which 10 met all inclusion criteria for the study. There was substantial heterogeneity among studies. The summary estimate for the annual risk of ischemic stroke was 1.61% (95% confidence interval 0%-3.23%) for CHA2DS2-VASc score of 1, meeting the theoretical threshold for using novel oral anticoagulants (0.9%), but below the threshold for warfarin (1.7%). The summary incident risk of ischemic stroke was 0.68% (95% confidence interval 0.12%-1.23%) for CHA2DS2-VASc score of 0 and 2.49% (95% confidence interval 1.16%-3.83%) for CHA2DS2-VASc score of 2.
  
  
  
  Our meta-analysis of ischemic stroke risk in atrial fibrillation patients suggests that those with CHA2DS2-VASc score of 1 may be considered for a novel oral anticoagulant, but because of high heterogeneity, the decision should be based on individual patient characteristics.
authors.affiliation: From the Division of Neurology, Department of Medicine, University of Toronto, Toronto, ON, Canada (R.A.J.); Ivey Business School, Western University, London, ON, Canada (L.E.C.); Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada (L.E.C.); Department of Clinical Neurological Sciences, London Health Sciences Centre. Western University, London, ON, Canada (L.A.S.); and Stroke Outcomes Research Unit, Division of Neurology, Department of Medicine, St Michael's Hospital, University of Toronto, and Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada (G.S.).
authors.forename: Raed A
authors.initials: RA
authors.lastname: Joundi
authors.affiliation: From the Division of Neurology, Department of Medicine, University of Toronto, Toronto, ON, Canada (R.A.J.); Ivey Business School, Western University, London, ON, Canada (L.E.C.); Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada (L.E.C.); Department of Clinical Neurological Sciences, London Health Sciences Centre. Western University, London, ON, Canada (L.A.S.); and Stroke Outcomes Research Unit, Division of Neurology, Department of Medicine, St Michael's Hospital, University of Toronto, and Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada (G.S.).
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Cipriano
authors.affiliation: From the Division of Neurology, Department of Medicine, University of Toronto, Toronto, ON, Canada (R.A.J.); Ivey Business School, Western University, London, ON, Canada (L.E.C.); Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada (L.E.C.); Department of Clinical Neurological Sciences, London Health Sciences Centre. Western University, London, ON, Canada (L.A.S.); and Stroke Outcomes Research Unit, Division of Neurology, Department of Medicine, St Michael's Hospital, University of Toronto, and Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada (G.S.).
authors.forename: Luciano A
authors.initials: LA
authors.lastname: Sposato
authors.affiliation: From the Division of Neurology, Department of Medicine, University of Toronto, Toronto, ON, Canada (R.A.J.); Ivey Business School, Western University, London, ON, Canada (L.E.C.); Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada (L.E.C.); Department of Clinical Neurological Sciences, London Health Sciences Centre. Western University, London, ON, Canada (L.A.S.); and Stroke Outcomes Research Unit, Division of Neurology, Department of Medicine, St Michael's Hospital, University of Toronto, and Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada (G.S.). saposnikg@smh.ca.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Saposnik
mesh_terms: D001281:Atrial Fibrillation / Q000150:complications*; D002545:Brain Ischemia / Q000209:etiology*; D006801:Humans; D012720:Severity of Illness Index; D020521:Stroke / Q000209:etiology*
keywords: CHA2DS2-VASc; atrial fibrillation; ischemic stroke; meta-analysis; stroke