title: Underuse and overuse of anticoagulation for atrial fibrillation: A study in Indigenous and non-Indigenous Australians.
abstract: BACKGROUND
  Atrial fibrillation (AF) is a leading cause of preventable stroke in Australia. Given that anticoagulation therapy can significantly reduce this stroke risk, we sought to characterise anticoagulation use in Indigenous and non-Indigenous Australians with AF.
  
  
  METHODS
  Administrative, clinical and prescription data from patients with AF were linked. Anticoagulation use was characterised according to guideline-recommended risk scores and Indigenous status.
  
  
  RESULTS
  19,613 individuals with AF were studied. Despite a greater prevalence of other risk factors, Indigenous Australians were significantly younger than their non-Indigenous counterparts (p<0.001) and thus had lower CHADS₂- (1.19±0.32 vs 1.99±0.47, p<0.001) and CHA₂DS₂VASc-scores (1.47 ± 0.03 vs 2.82 ± 0.08, p<0.001). Correspondingly, the percentage of Indigenous Australians with CHADS₂ ≥ 2 (39.6% vs 44.1%, p<0.001) and CHA₂DS₂VASc-scores ≥ 2 (62.9% vs 78.8%, p<0.001) was also lower. Indigenous Australians, however, had greater rates of under- and over-anticoagulation. Overall, 72.1% and 68.9% of Indigenous and non-Indigenous Australians with CHADS₂ scores ≥2, and 76.3% and 71.3% with CHA₂DS₂VASc scores ≥2, were under-anticoagulated. Similarly, 27.4% and 24.1% of Indigenous and non-Indigenous Australians with CHADS₂ scores=0, and 24.0% and 16.7% with CHA₂DS₂VASc-scores=0, were over-anticoagulated. In multivariate analyses, Indigenous Australians were more likely to receive under- or over-anticoagulation according to CHADS₂- or CHA₂DS₂VASc-score (p=0.045 and p<0.001 respectively).
  
  
  CONCLUSIONS
  Anticoagulation for AF is frequently not prescribed in accordance with guideline recommendations. Under-anticoagulation in those at high stroke risk, and over-anticoagulation in those at low risk, is common and more likely in Indigenous patients with AF. Improving adherence to guideline recommendations for anticoagulation in AF may reduce both ischaemic and haemorrhagic strokes in Indigenous and non-Indigenous Australians.
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Christopher X
authors.initials: CX
authors.lastname: Wong
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Sarah W
authors.initials: SW
authors.lastname: Lee
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Siang Wei
authors.initials: SW
authors.lastname: Gan
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Mahajan
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Geetanjali
authors.initials: G
authors.lastname: Rangnekar
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Rajeev K
authors.initials: RK
authors.lastname: Pathak
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Darragh
authors.initials: D
authors.lastname: Twomey
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Carlee
authors.initials: C
authors.lastname: Schultz
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Anand N
authors.initials: AN
authors.lastname: Ganesan
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Brooks
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Kurt C
authors.initials: KC
authors.lastname: Roberts-Thomson
authors.affiliation: Aboriginal Health Research, South Australian Health and Medical Research Institute (SAHMRI), School of Population Health, University of South Australia, Adelaide, Australia.
authors.forename: Alex
authors.initials: A
authors.lastname: Brown
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Dennis H
authors.initials: DH
authors.lastname: Lau
authors.affiliation: Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia. Electronic address: prash.sanders@adelaide.edu.au.
authors.forename: Prashanthan
authors.initials: P
authors.lastname: Sanders
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000453:epidemiology / Q000208:ethnology*; D001315:Australia / Q000453:epidemiology; D015897:Comorbidity; D005006:Ethnicity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D044382:Population Groups / Q000706:statistics & numerical data*; D017410:Practice Guidelines as Topic; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data; D000067490:Prescription Drug Overuse / Q000706:statistics & numerical data*; D015995:Prevalence; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology / Q000208:ethnology / Q000517:prevention & control
chemical_list: D000925:Anticoagulants
keywords: Anticoagulation; Atrial fibrillation; Ethnicity; Indigenous; Stroke