Acute lower gastrointestinal bleeding: A population‐based five‐year follow‐up study

Background: Data on the natural history of acute lower gastrointestinal bleeding (ALGIB) are lacking. We evaluated five-year bleeding risk and mortality in ALGIB patients and controls. Furthermore, we aimed to find predictors of rebleeding. Methods: This was a population-based retrospective case-control study conducted at the National University Hospital of Iceland, and included every individual who underwent endoscopy in 2010-2011. ALGIB was defined as rectal bleeding leading to hospitalisation or occurring in a hospitalised patient. Controls were randomly selected from those who underwent endoscopy in the same time period but who did not have GIB, and were matched for sex and age. Patients were followed up five years after index bleeding. Rebleeding was defined as ALGIB >14 days after index bleeding. Results: In total, 2294 patients underwent 2602 colonoscopies in 2010-2011. Of those, 319 (14%) had ALGIB. The mean age for cases and controls was 64 and 65 years (±19.3-20.7), respectively, and females accounted for 51-52% of the study population. For ALGIB patients, the five-year risk of a bleeding was 20% (95% confidence interval (CI) 15-24%) compared to 3% (95% CI 1-5%) in controls (log rank < 0.0001; co-morbidity-adjusted hazard ratio (HR) 6.9 (95% CI 3.4-14)). Only 37% of bleeders had the same cause of index bleeding and rebleeding. In ALGIB patients, age and inflammatory bowel disease (IBD) were predictors of rebleeding, with odds ratios per 10 years of 1.3 (95% CI 1.1-1.6) and 4.3 (95% CI 1.5-12), respectively. Bleeders did not have a higher risk of five-year mortality compared to controls (HR = 1.2; 95% CI 0.87-1.6). Conclusions: One fifth of ALGIB patients had rebleeding during follow-up. Age and IBD were independent predictors of rebleeding. ALGIB was not associated with lower five-year survival.