2.1. Trial design
CHEC2017
From April 18, 2020, to June 28, 2020, we conducted a prospective, randomized, patient-blind, controlled, tandem colonoscopy, pilot trial from a single tertiary referral center. Patients who underwent colonoscopy were randomly assigned according to a 1:1 ratio to either a trial group with 2 forward examination and cecal retroflexion observed in the ascending colon or a control group with repeated 2 examination in the ascending colon. AMR and related information were compared between the 2 groups. This trial was undertaken in the gastrointestinal (GI) Endoscopy Center of the Naval Medical University First Affiliated Hospital in Shanghai, China. All the patients were referred from outpatient and inpatient departments of the same medical center. This trail was approved by the Medical Ethics Committee of the Naval Medical University First Affiliated Hospital (EC Approval No.: CHEC2017-142), and all the patients gave written informed consent before colonoscopy. The trial was registered at ClinicalTrials.gov (identifier, NCT03355443). Prof Yu En-Da and other authors had access to the study data and had reviewed and approved the final manuscript. However, there were still some differences between the actual trial and the original study protocol approved by the Medical Ethics Committee. First, our colonoscopy system under retroflexion was not able to visualize all the proximal colon as expected, and second, the timing and sample size of our study did not go as planned due to the impact of COVID-19.