title: Prospective cohort study to determine if trial efficacy of anticoagulation for stroke prevention in atrial fibrillation translates into clinical effectiveness.
abstract: OBJECTIVE
  To determine whether trial efficacy of prophylaxis with warfarin for patients with atrial fibrillation at high risk of stroke translates into effectiveness in clinical practice.
  
  
  METHODS
  Two year prospective cohort study.
  
  
  METHODS
  District general hospital.
  
  
  METHODS
  167 patients with atrial fibrillation and at high stroke risk who were eligible for anticoagulation.
  
  
  METHODS
  Long term anticoagulation with warfarin at adjusted doses to maintain an international normalised ratio of 2.0-3.0.
  
  
  METHODS
  Comparison of patient characteristics, comorbidity, anticoagulation control, stroke rate, and haemorrhagic complications with pooled data from five randomised controlled trials.
  
  
  RESULTS
  Patients in the study group were seven years older (95% confidence interval 4 to 10) and comprised 33% more women than patients in the pooled trials. The international normalised ratio was in the target range for 61% of the time (range 37%-85%), below for 26% of the time (range 8%-32%), and above for 13% of the time (range 6%-26%). The time that patients in the study group spent in the target range was significantly less than in the pooled analysis. The incidence of stroke in the study group (2.0% per year, 0.7% to 4. 4%) was comparable to that of patients receiving warfarin in pooled studies (1.4%, 0.8% to 2.3%). Per year the incidence of major (1.7% v 1.6%) and minor (5.4% v 9.2%) bleeding complications was also similar.
  
  
  CONCLUSIONS
  Rates of stroke and major haemorrhage after anticoagulation in clinical practice were comparable to those obtained from pooled data from randomised controlled studies for patients with atrial fibrillation at high risk of stroke.
authors.affiliation: Department of Medicine, Guy's, King's, and St Thomas's School of Medicine, London SE5 9PJ. lalit.kalra@kcl.ac.uk
authors.forename: L
authors.initials: L
authors.lastname: Kalra
authors.forename: G
authors.initials: G
authors.lastname: Yu
authors.forename: I
authors.initials: I
authors.lastname: Perez
authors.forename: A
authors.initials: A
authors.lastname: Lakhani
authors.forename: N
authors.initials: N
authors.lastname: Donaldson
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000097:blood / Q000188:drug therapy*; D005260:Female; D006470:Hemorrhage / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D019934:International Normalized Ratio; D008297:Male; D015201:Meta-Analysis as Topic; D011446:Prospective Studies; D020521:Stroke / Q000453:epidemiology / Q000517:prevention & control*; D016896:Treatment Outcome; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin