title: Incidence of intracranial bleeds in new users of low-dose aspirin: a cohort study using The Health Improvement Network.
abstract: Essentials Intracranial bleeds (ICB) are serious clinical events that have been associated with aspirin use. Incidence rates of ICB were calculated among new-users of low-dose aspirin in the UK (2000-2012). Over a median follow-up of 5.58 years, the incidence of ICB was 0.08 per 100 person-years. Our estimates are valuable for inclusion in risk-benefit assessments of low-dose aspirin use.
  
  
  
  Background Low-dose aspirin protects against both ischemic cardiovascular (CV) events and colorectal cancer (CRC). However, low-dose aspirin may be associated with a slightly increased risk of intracranial bleeds (ICBs). Objectives To obtain the incidence rates of ICBs overall and by patient subgroups among new users of low-dose aspirin. Patients/Methods Using The Health Improvement Network (THIN) UK primary-care database (2000-2012), we identified a cohort of new users of low-dose aspirin aged 40-84 years (N = 199 079; mean age at start of follow-up, 63.9 years) and followed them for up to 14 years (median 5.58 years). Incident ICB cases were identified and validated through linkage to hospitalization data and/or review of THIN records with free-text comments. Incidence rates with 95% confidence intervals (CIs) were calculated. Results Eight hundred and eighty-one incident ICBs cases were identified: 407 cases of intracerebral hemorrhage (ICH), 283 cases of subdural hematoma (SDH), and 191 cases of subarachnoid hemorrhage (SAH). Incidence rates per 100 person-years were 0.08 (95% CI 0.07-0.08) for all ICBs, 0.04 (95% CI 0.03-0.04) for ICH, 0.03 (95% CI 0.02-0.03) for SDH, and 0.02 (95% CI 0.01-0.02) for SAH. The ICB incidence rates per 100 person-years for individuals with an indication of primary CV disease prevention were 0.07 (95% CI 0.06-0.07) and 0.09 (95% CI 0.08-0.10) for secondary CV disease prevention. Incidence rates were higher in men for SDH, and higher in women for ICH and SAH. Conclusions Our results provide valuable estimates of the absolute ICB risk for incorporation into risk-benefit assessments of low-dose aspirin use.
authors.affiliation: Spanish Center for Pharmacoepidemiologic Research (CEIFE), Madrid, Spain.|Department of Preventive Medicine and Public Health, Faculty of Medicine, Complutense University of Madrid, Madrid, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Cea Soriano
authors.affiliation: Department of Neurology, Odense University Hospital, Odense University, Odense, Denmark.|Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark.
authors.forename: D
authors.initials: D
authors.lastname: Gaist
authors.affiliation: Epidemiology, Bayer AG, Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Soriano-Gabarró
authors.affiliation: Spanish Center for Pharmacoepidemiologic Research (CEIFE), Madrid, Spain.
authors.forename: L A
authors.initials: LA
authors.lastname: García Rodríguez
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006408:Hematoma, Subdural / Q000139:chemically induced; D006801:Humans; D015994:Incidence; D020300:Intracranial Hemorrhages / Q000139:chemically induced* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D013345:Subarachnoid Hemorrhage / Q000139:chemically induced; D006113:United Kingdom
chemical_list: D001241:Aspirin
keywords: aspirin; cerebral hemorrhage; intracranial hemorrhages; stroke; subarachnoid hemorrhage; subdural hematoma