title: A prospective study of aspirin use and the risk of gastrointestinal bleeding in men.
abstract: OBJECTIVE
  Data regarding the influence of dose and duration of aspirin use on risk of gastrointestinal bleeding are conflicting.
  
  
  METHODS
  We conducted a prospective cohort study of 32,989 men enrolled in the Health Professionals Follow-up Study (HPFS) in 1994 who provided biennial aspirin data. We estimated relative risk of major gastrointestinal bleeding requiring hospitalization or a blood transfusion.
  
  
  RESULTS
  During 14 years of follow-up, 707 men reported an episode of major gastrointestinal bleeding over 377,231 person-years. After adjusting for risk factors, regular aspirin use (≥2 times/week) had a multivariate relative risk (RR) of gastrointestinal bleeding of 1.32 (95% confidence interval [CI], 1.12-1.55) compared to non-regular use. The association was particularly evident for upper gastrointestinal bleeding (multivariate RR, 1.49; 95% CI, 1.16-1.92). Compared to men who denied any aspirin use, multivariate RRs of upper gastrointestinal bleeding were 1.05 (95% CI 0.71-1.52) for men who used 0.5-1.5 standard tablets/week, 1.31 (95% CI 0.88-1.95) for 2-5 aspirin/week, 1.63 (95% CI, 1.15-2.32) for 6-14 aspirin/week and 2.40 (95% CI, 1.10-5.22) for >14 aspirin/week (P(trend)<0.001). The relative risk also appeared to be dose-dependent among short-term users <5 years; P(trend)<.001) and long-term users (≥5 years; P(trend) = 0.015). In contrast, after controlling for dose, increasing duration of use did not appear to be associated with risk (P(trend) = 0.749).
  
  
  CONCLUSIONS
  Regular aspirin use increases the risk of gastrointestinal bleeding, especially from the upper tract. However, risk of bleeding appears to be more strongly related to dose than to duration of use. Risk of bleeding should be minimized by using the lowest effective dose among short-term and long-term aspirin users.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America. eshuang@partners.org
authors.forename: Edward S
authors.initials: ES
authors.lastname: Huang
authors.forename: Lisa L
authors.initials: LL
authors.lastname: Strate
authors.forename: Wendy W
authors.initials: WW
authors.lastname: Ho
authors.forename: Salina S
authors.initials: SS
authors.lastname: Lee
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Chan
mesh_terms: D000368:Aged; D001241:Aspirin / Q000009:adverse effects*; D001803:Blood Transfusion; D015331:Cohort Studies; D006471:Gastrointestinal Hemorrhage / Q000139:chemically induced*; D006470:Hemorrhage / Q000139:chemically induced*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012306:Risk; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
chemical_list: D001241:Aspirin