Timing of Colonoscopy and Factors Indicating Early Colonoscopy in Acute Lower Gastrointestinal Bleeding: A Large-Scale Multicenter Cohort Study

Background: Optimal timing of colonoscopy for acute lower gastrointestinal bleeding is controversial, and it is unclear which patients benefit from early colonoscopy. The reported proportion of hemodynamically unstable patients is lower in randomized controlled trials than in observational studies. Methods: We studied 6,311 patients admitted for acute hematochezia in 49 Japanese hospitals, named the CODE-BLUE J Study. One propensity score-matched cohort comprised patients who underwent early (<24 hours) vs. non-early (24–96 hours) colonoscopy; the other comprised elective (24–48 hours) vs. late (48–96 hours) colonoscopy. Interaction term models were used to identify characteristics of patients who benefited from early colonoscopy. Findings: We compared 1,960 pairs of early vs. non-early patients. The early group showed higher rates of identification of stigmata of recent hemorrhage (SRH), endoscopic hemostasis (31% vs. 18%, P<0·001), and 30-day rebleeding, and a shorter length of hospital stay. The interventional radiology (IVR)/surgery rate was marginally lower in the early cohort (1·1% vs. 1·8%, P=0·083). Thirty-day mortality and blood transfusion rates were not significantly different between the groups. Of 810 pairs of elective vs. late patients, the elective group had a higher rate of SRH identification and shorter length of hospital stay. Systolic blood pressure (SBP) ≤100 mmHg at admission modified the qualitative effect of timing (early vs non-early) on requirement for IVR/surgery (odds ratio: 2·58 [95% confidence interval: 1·00–6·66] vs 0·98 [0·55–1·40]; P for interaction=0·047). Interpretation: Early colonoscopy increased the rates of SRH identification and endoscopic hemostasis and reduced the length of hospital stay but did not improve rebleeding and mortality. Early colonoscopy benefited patients with low SBP at presentation. Funding Information: This work was partially supported by grants from the Ministry of Health, Labour and Welfare, JSPS (KAKENHI), Smoking Research Foundation, Takeda Science Foundation, and National Center for Global Health and Medicine. Declaration of Interests: The authors have no relevant conflicts of interest to declare. Ethics Approval Statement: Approval from the ethical committees and institutional review boards of all 49 participating hospitals was obtained using the opt-out method. The requirement for patient consent was waived considering the retrospective nature of the study.