doi:10.1016/j.cgh.2018.05.061engCea Soriano, L.Lanas, A.Soriano-Gabarró, M.García Rodríguez, L.A.Incidence of Upper and Lower Gastrointestinal Bleeding in New Users of Low-Dose AspirinART-2019-110672Background & Aims: There are few data on the incidence of upper and lower gastrointestinal bleeding (UGIB and LGIB) from observational studies of low-dose aspirin users. We aimed to estimate incidence rates of UGIB and LGIB in a large cohort of new users of low-dose aspirin in the United Kingdom, with subanalyses of hospitalization status and fatalities. Methods: We performed a population-based study of 199, 079 new users of low-dose aspirin (median age, 64.0 years) identified from the Health Improvement Network primary care database (2000–2012). Individuals were followed for a median 5.4 years (maximum, 14 years) to identify new cases of UGIB and LGIB. Following multistep validation, we calculated overall and age- and sex-specific incidence rates; we performed subanalyses for health care use and death within 30 days of GIB. We also estimated rates within a matched (1:1) cohort of nonusers of low-dose aspirin at the start of the follow-up period. Results: The low-dose aspirin users had 1115 UGIB events and 1936 LGIB events; most subjects with UGIB events (58.9%) were hospitalized, whereas most subjects with LGIB events were referred to secondary care (72.8%). Crude incidence rates of GIB per 1000 person-years were 0.97 for subjects with UGIB (95% CI, 0.91–1.02) and 1.68 for subjects with LGIB (95% CI, 1.60–1.75). Incidence rates per 1000 person-years for patients hospitalized for GIB were 0.57 for UGIB (95% CI, 0.53–0.61) and 0.45 for LGIB (95% CI, 0.42–0.49); for referred (but not hospitalized) cases, these values were 0.39 for UGIB (95% CI, 0.36–0.43) and 1.22 for LGIB (1.16–1.29). Incidence rates per 1000 person-years were 0.06 for fatal UGIB (95% CI, 0.04–0.07), 0.01 for fatal LGIB (95% CI, 0.01–0.02), 0.91 for nonfatal UGIB (95% CI, 0.86–0.97), and 1.66 for nonfatal LGIB (95% CI, 1.59–1.74). Among nonusers of low-dose aspirin, incidence rates per 1000 person-years were 0.67 (95% CI, 0.63–0.75) for UGIB and 0.76 (95% CI, 0.72–0.82) for LGIB. Conclusion: In a population-based study of low-dose aspirin users, the incidence of LGIB was higher than the incidence of UGIB. However, incidence rates of hospitalized GI bleeds and 30-day mortality rates were lower for LGIB than for UGIB. These estimates are valuable for benefit–risk assessments of low-dose aspirin for cardiovascular and colorectal cancer prevention.2019http://zaguan.unizar.es/record/7957810.1016/j.cgh.2018.05.061http://zaguan.unizar.es/record/79578oai:zaguan.unizar.es:79578Clinical Gastroenterology and Hepatology 17, 5 (2019), 887-895.e6All rights reservedhttp://www.europeana.eu/rights/rr-f/info:eu-repo/semantics/openAccess