A multicenter, randomized controlled trial comparing the identification rate of stigmata of recent hemorrhage and rebleeding rate between early and elective colonoscopy in outpatient-onset acute lower gastrointestinal bleeding: study protocol for a randomized controlled trial

BACKGROUND: The clinical benefit of early colonoscopy within 24 h of arrival in patients with severe acute lower gastrointestinal bleeding (ALGIB) remains controversial. This trial will compare early colonoscopy (performed within 24 h) versus elective colonoscopy (performed between 24 and 96 h) to examine the identification rate of stigmata of recent hemorrhage (SRH) in ALGIB patients. We hypothesize that, compared with elective colonoscopy, early colonoscopy increases the identification of SRH and subsequently improves clinical outcomes. METHODS: This trial is an investigator-initiated, multicenter, randomized, open-label, parallel-group trial examining the superiority of early colonoscopy over elective colonoscopy (standard therapy) in ALGIB patients. The primary outcome measure is the identification of SRH. Secondary outcomes include 30-day rebleeding, success of endoscopic treatment, need for additional endoscopic examination, need for interventional radiology, need for surgery, need for transfusion during hospitalization, length of stay, 30-day thrombotic events, 30-day mortality, preparation-related adverse events, and colonoscopy-related adverse events. The sample size will enable detection of a 9% SRH rate in elective colonoscopy patients and a SRH rate of ≥ 26% in early colonoscopy patients with a risk of type I error of 5% and a power of 80%. DISCUSSION: This trial will provide high-quality data on the benefits and risks of early colonoscopy in ALGIB patients. TRIAL REGISTRATION: UMIN-CTR Identifier, UMIN000021129. Registered on 21 February 2016; ClinicalTrials.gov Identifier, NCT03098173. Registered on 24 March 2017. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13063-018-2558-y) contains supplementary material, which is available to authorized users.