Objectives To identify incidence and risk factors for new-onset gastrointestinal bleeding (GIB) in a medical intensive care unit (ICU), a topic for which there is a paucity of recent studies.

Design Retrospective cohort study.

Setting Medical ICUs at our tertiary-care hospital, from 2007 to 2013.

Patients Patients who developed clinically significant GIB after entering the ICU.

Interventions Univariable and multivariable analyses.

Main outcome measures Incidence and risk factors for development of GIB.

Results 4439 patients entered the medical ICU without a pre-existing GIB and 58 (1.3%) developed GIB while in the ICU. Risk factors included length of ICU stay (OR per additional day 1. 06; 95% CI 1.04 to 1.09) and elevated creatinine on ICU admission (OR 2.35; 95% CI 1.18 to 4.68, p=0.02). Elevated bilirubin on ICU admission (OR 2.08; 95% CI 0.97 to 4.47, p=0.06), and elevated aspartate transaminase (AST) on ICU admission (OR 2.20; 95% CI 0.96 to 5.03, p=0.06) trended towards increased risk of GIB that did not meet statistical significance. Age, gender, admission coagulation studies and mechanical ventilation were not predictive of GIB. Among those patients with new-onset GIB in the ICU, 47% died during that hospitalisation, as compared with those 30% of those without a GIB, p<0.01.

Conclusions Onset of GIB is now an infrequent occurrence in the ICU setting; however those with elevated bilirubin, AST and creatinine upon admission, and with longer length of ICU stay appear at increased risk and may benefit from closer monitoring.