title: Gastrointestinal haemorrhage in atrial fibrillation patients: impact of quality of anticoagulation control.
abstract: OBJECTIVE
  Gastrointestinal haemorrhage is a common complication of antiplatelet and anticoagulation therapy. The aim of this study is to evaluate the impact of warfarin with different time in therapeutic ranges (TTRs) on the risk of major gastrointestinal haemorrhage in atrial fibrillation (AF) patients compared with aspirin.
  
  
  RESULTS
  In this observational study, 5426 Chinese AF patients (77.7 ± 10.7 years, female: 53.1%) with a CHA2DS2-VASc score of ≥1 were included in the final analysis: of which, 3832 patients (70.6%) were taking aspirin and 1594 patients (29.4%) were taking warfarin, whereas the remaining patients did not receive any anticoagulation. The mean baseline HAS-BLED score was 2.22 ± 0.93. Among those on warfarin, the median TTR was 39.2%. After a mean follow-up of 3.6 years (19 777 patient-years), 262 patients developed a gastrointestinal haemorrhage requiring transfusion (4.83%), with an annual incidence of 1.32%/year. Annual incidences of gastrointestinal haemorrhage requiring transfusion among patients on aspirin and warfarin were 1.53%/year and 1.00%/year, respectively. For patients on warfarin, the incidence of gastrointestinal haemorrhage increased progressively with higher HAS-BLED scores, from 0.93%/year for those with a HAS-BLED score of ≤1 to 1.68%/year for those with a HAS-BLED score of ≥3, and decreased progressively with an increasing TTR from 1.69%/year for patients in the lowest quartile of TTR to only 0.51%/year for those in the top quartile.
  
  
  CONCLUSIONS
  Aspirin is overall associated with a higher risk of gastrointestinal haemorrhage compared with warfarin, despite the suboptimal TTR in the study population. For patients on warfarin, a HAS-BLED score at baseline prior to commencing anticoagulation positively correlates with gastrointestinal haemorrhage. A poor TTR was associated with a higher risk of gastrointestinal haemorrhage.
authors.affiliation: Division of Cardiology, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Pak-Hei
authors.initials: PH
authors.lastname: Chan
authors.affiliation: Division of Cardiology, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Wen-Hua
authors.initials: WH
authors.lastname: Li
authors.affiliation: Division of Cardiology, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Jo-Jo
authors.initials: JJ
authors.lastname: Hai
authors.affiliation: Division of Neurology, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Koon-Ho
authors.initials: KH
authors.lastname: Chan
authors.affiliation: Division of Cardiology, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Hung-Fat
authors.initials: HF
authors.lastname: Tse
authors.affiliation: Division of Clinical Pharmacology, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Bernard Man-Yung
authors.initials: BM
authors.lastname: Cheung
authors.affiliation: Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Esther W
authors.initials: EW
authors.lastname: Chan
authors.affiliation: Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Ian C K
authors.initials: IC
authors.lastname: Wong
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Wai-Keung
authors.initials: WK
authors.lastname: Leung
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Ivan Fan-Ngai
authors.initials: IF
authors.lastname: Hung
authors.affiliation: University of Birmingham, Centre for Cardiovascular Sciences, City Hospital, Birmingham, UK.
authors.forename: Gregory Y H
authors.initials: GY
authors.lastname: Lip
authors.affiliation: Division of Cardiology, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China cwdsiu@hku.hk.
authors.forename: Chung-Wah
authors.initials: CW
authors.lastname: Siu
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects* / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000150:complications*; D002681:China / Q000453:epidemiology; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000139:chemically induced* / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D020521:Stroke / Q000209:etiology / Q000517:prevention & control*; D015912:Thrombolytic Therapy / Q000009:adverse effects*
chemical_list: D000925:Anticoagulants
keywords: Atrial fibrillation; Gastrointestinal haemorrhage; Time in therapeutic range