Adenoma detection rate in fecal immunochemical test positive colonoscopies: a population-based observational study

Background and aims: Neoplasia-related indicators, such as adenoma detection rate (ADR), are a priority in the quality improvement process for colonoscopy. Our aim was to assess and compare different detection and characterization indicators in fecal occult blood test (FOBT)-positive colonoscopies, to analyze the factors influencing their variance, and to propose benchmarks. Methods: Retrospective analysis of prospectively collected data from all colonoscopies performed between 2007 and 2019 after a positive guaiac-based FOBT or a fecal immunochemical test (FIT) in the population-based colorectal cancer (CRC) screening program conducted in Alsace, part of the French national program. Detection indicators included ADR, NewADR (including proximal serrated lesions), mean number of adenomas per colonoscopy, and proximal serrated lesion detection rate. Characterization indicators included non-neoplastic polyp detection rate. Results: Overall, 13.455 FIT-positive colonoscopies were performed by 116 endoscopists. The overall ADR was 57.6% (95%CI 56.8-58.5). For each 10 microg/g increase in fecal hemoglobin concentration, a 2% increase in ADR was observed. Endoscopists whose ADR was [≥]55% were high detectors for all neoplasia, including proximal serrated lesions and number of adenomas. The non-neoplastic polyp detection rate was 39.5% in highest detectors (ADR >70%), significantly higher than in lower detectors (21.4%) (p<0.001). There was a strong correlation between detection and characterization indicators, e.g. between proximal serrated lesion and non-neoplastic polyp detection rates (Pearson = 0.73; p<0.01). Conclusions: A single indicator, NewADR, including proximal serrated lesions, is enough to assess the neoplasia yield of colonoscopy provided the target standard is raised between 55% and 70% in FIT-positive colonoscopies (65-80% in men, 45-60% in women).