title: Patterns of warfarin use in subgroups of patients with atrial fibrillation: a cross-sectional analysis of 430 general practices in the United Kingdom.
abstract: BACKGROUND
  Despite the proven efficacy of warfarin, its use in patients with Atrial Fibrillation (AF) is reportedly low. We investigated the underuse and overuse of warfarin in the management of AF in general practices in the United Kingdom (UK) against the National Institute of Clinical Excellence (NICE, UK) guidelines whilst seeking to identify subgroups of AF patients to inform efforts to optimise warfarin use.
  
  
  METHODS
  A retrospective database analysis to determine warfarin prescribing using tree models based on 50,361 patients with AF (classified as low, moderate and high risk of stroke using CHADS2) from 430 general practices in the UK.
  
  
  RESULTS
  Over one-third (37.0%, 4573/12,351) of low risk AF patients were on warfarin, compared with 47.1% (8349/17,709) moderate risk AF patients and 54.9% (11,142/20,301) high risk AF patients. Clinical subgroups (n = 15 low risk subgroups, n = 15 medium risk subgroups, n = 22 high risk subgroups) were identified. Several factors not supported by current guidelines (age, BMI, dementia, gender) were associated with the use of warfarin. Gender and BMI were associated with warfarin use in low and medium risk AF patients but not in high risk AF patients.
  
  
  CONCLUSIONS
  Whilst NICE guidelines suggest that all high risk AF patients should be on warfarin, half of those at moderate risk should be on warfarin and none of those at low risk should be on warfarin, we found evidence of over and under use of warfarin. Interventions to optimise warfarin therapy tailored to and targeting specific subgroups of AF patients identified by the tree models are required.
authors: School of Health and Population Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
authors: Mohammed A
authors: MA
authors: Mohammed
authors: Tom
authors: T
authors: Marshall
authors: Krishnarajah
authors: K
authors: Nirantharakumar
authors: Andrew
authors: A
authors: Stevens
authors: David
authors: D
authors: Fitzmaurice
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy*; D003430:Cross-Sectional Studies; D011307:Drug Prescriptions / Q000706:statistics & numerical data; D005260:Female; D058006:General Practice / Q000706:statistics & numerical data*; D019983:Guideline Adherence / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D012306:Risk; D006113:United Kingdom; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin
references: Lancet. 2012 Feb 18;379(9816):648-61
references: 22166900
references: Clin Res Cardiol. 2011 Oct;100(10):897-905
references: 21533828
references: J Med Syst. 2002 Oct;26(5):445-63
references: 12182209
references: Cerebrovasc Dis. 2006;21(3):187-93
references: 16388194
references: Europace. 2008 Jun;10(6):674-80
references: 18403385
references: BMJ. 2002 Jan 12;324(7329):71-86
references: 11786451
references: Stroke. 2008 Jan;39(1):227-30
references: 18048861
references: Heart. 2006 Aug;92(8):1064-70
references: 16387813
references: Health Policy. 2005 Mar;71(3):315-31
references: 15694499
references: Am J Cardiol. 1994 Aug 1;74(3):236-41
references: 8037127
references: Lancet. 2007 Aug 11;370(9586):493-503
references: 17693178
references: BMC Fam Pract. 2012 Feb 03;13:5
references: 22304704
references: Cochrane Database Syst Rev. 2007 Jul 18;(3):CD006186
references: 17636831
references: Circulation. 2007 Oct 9;116(15):1725-35
references: 17923583
references: Chest. 2008 Jun;133(6 Suppl):546S-592S
references: 18574273
references: J Am Coll Cardiol. 2011 Mar 15;57(11):e101-98
references: 21392637
references: Pharmacoepidemiol Drug Saf. 2009 Jan;18(1):76-83
references: 19065600
references: Ann Intern Med. 2009 Sep 1;151(5):297-305
references: 19721017
references: J Am Coll Cardiol. 2011 Jan 11;57(2):173-80
references: 21111555
references: Clin Chest Med. 2009 Sep;30(3):489-93, viii
references: 19700047
references: N Engl J Med. 1982 Apr 29;306(17):1018-22
references: 7062992
references: Am J Med. 2010 Jul;123(7):638-645.e4
references: 20609686
references: Circulation. 1998 Sep 8;98(10):946-52
references: 9737513
references: Eur Heart J. 2006 Aug;27(16):1979-2030
references: 16885201
references: Cochrane Database Syst Rev. 2005 Jul 20;(3):CD001927
references: 16034869
references: Am J Med. 2002 Oct 1;113(5):359-64
references: 12401529
references: Stroke. 1991 Aug;22(8):983-8
references: 1866765
references: Eur Heart J. 2010 Oct;31(19):2369-429
references: 20802247