Takafumi Katayama

OBJECTIVES: Bowel preparation for colonoscopy can lead to serious adverse events (AEs), raising significant safety concerns in colorectal cancer (CRC) screening. A systematic review of these serious AEs in Japan was performed to explore potential management strategies. METHODS: The Ovid-MEDLINE and Ichushi databases were searched from inception to March 2024. Domestic studies that reported serious AEs in adults aged 18 years and older who were administered bowel cleansing agents or laxatives for a scheduled colonoscopy, regardless of its purpose, were extracted. Serious AEs were defined as those requiring hospitalization or extended hospital stays. Selected studies were assessed for quality verification using the established checklist. RESULTS: A total of 5049 articles were identified through database searches, and 54 articles were extracted based on selection criteria. Reports of the frequency of serious AEs were based on one case series study, which found 13.9 cases of bowel obstruction and 2.3 cases of bowel perforation per 100,000 colonoscopies. Multiple serious AEs caused by different agents were identified in 78 cases across 54 articles. These AEs were predominantly observed in elderly individuals and those with comorbidities. Though most cases were associated with diagnostic tests for symptomatic patients, some were also observed in primary screening or fecal test-positive individuals. The most common AE was induced by bowel obstruction, primarily in abdominally symptomatic patients, including one fatality. CONCLUSION: The frequency and characteristics of serious AEs associated with bowel preparation for colonoscopy in Japan were presented. These findings may contribute to managing these AEs, specifically in CRC screening.

BACKGROUND: Demonstrating mortality reduction in new colorectal cancer (CRC) screening programs through randomized clinical trials (RCTs) is challenging. We systematically reviewed single-round program performance outcomes using a stepwise approach proposed by the World Endoscopy Organization CRC Screening Committee framework. METHODS: The MEDLINE, EMBASE, Central, and Ichushi Web databases were searched until October 28, 2024, to find RCTs comparing guaiac-based and immunochemical fecal occult blood testing (gFOBT and FIT), flexible sigmoidoscopy (FS), computed tomographic colonography (CTC), and total colonoscopy (TCS). Paired reviewers screened studies, extracted data, and assessed bias risk. A Bayesian random-effects network meta-analysis was conducted, and the certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation approach. The primary outcome was advanced neoplasia (AN) detection, and the secondary outcomes were participation and colorectal cancer (CRC) detection, all during the first screening round. RESULTS: Eighteen RCTs (437,072 invitees) were included. The risk of bias was low or raised some concerns for screening participation, but it was high for detection outcomes. In the network meta-analysis of 15 RCTs not allowing crossover, the FIT-based program had a higher AN detection rate than the gFOBT-based program (relative risk [RR] 2.48; 95% credible interval [CrI] 1.52-4.21; moderate certainty). AN detection rates were not different in the CTC- (RR 1.01; CrI 0.43-2.23; very low certainty) and TCS-based (RR 1.03; CrI 0.54-1.78; low certainty) programs compared with the FS-based program. All the visualization modality programs had higher AN detection rates than the FIT-based program (FS: RR 2.13 [CrI 1.38-3.77]; CTC 2.16 [1.11-4.51]; and TCS 2.19 [1.43-3.48]; all with low certainty). Low event rates precluded definitive conclusions regarding CRC detection (very low to low certainty). The TCS-based program had the worst participation rate (very low to low certainty). Comparative data allowing crossover were limited. CONCLUSIONS: This is the first network meta-analysis that evaluates program-level initial performance indicators. FIT-based programs likely detect more AN cases than gFOBT-based programs, while FS-, CTC-, and TCS-based programs may outperform FIT. Due to limitations in first-round results, long-term outcomes should be assessed after 10-15 years.