Adverse events of colonoscopy in a colorectal cancer screening programme with faecal immunochemical test: a population-based community-based observational study.

Objectives Colonoscopy is considered a safe examination, serious complications being uncommon. Our study aimed to assess the adverse events of colonoscopy in a colorectal cancer screening programme with faecal immunochemical test (FIT) and to compare them with those of a previous programme with guaiac-based faecal occult blood test (gFOBT). Design Retrospective observational study Setting Population-based community-based colorectal cancer screening programme organised in Alsace, part of the national French programme, with FIT from 2015 to 2018 and gFOBT from 2003 to 2014. Participants All residents aged 50 to 74 years having a colonoscopy performed for a positive FOBT. Main outcome measures Adverse events were recorded through prospective voluntary reporting by community gastroenterologists and retrospective postal surveys addressed to persons screened. Results Of 9576 colonoscopies performed for a positive FIT, 6194 (64.7%) were therapeutic. Overall, 180 adverse events were recorded (1.88%, 95% CI 1.61-2.15), 114 of them (1.19%, 95% CI 0.97-1.41) requiring hospitalisation, 55 (0.57, 95% CI 0.42-0.73) hospitalisation >24hrs, and 8 (0.08%, 95% CI 0.03-0.14) surgery. The main complications requiring hospitalisation were perforation (n=18, 0.19%, 95% CI 0.10-0.27) and bleeding (n=31, 0.32%, 95% CI 0.21-0.44). We observed one death (1 / 27,000 colonoscopies). Overall, 52 persons harbouring at least one adenoma ≥ 10 mm were detected for one adverse event requiring hospitalisation >24hrs. The rate of adverse events remained stable between gFOBT and FIT programmes. Conclusions The harms of colonoscopy in a colorectal cancer screening programme with FIT are more frequent than usually estimated, here six adverse events requiring hospitalisation >24hrs (three bleedings, two perforations), one necessitating surgery and 50 minor complications per 1000 colonoscopies. The price to be paid to save lives through colorectal cancer screening programmes is higher than what is stated in most pilots. Today, comparison between series dealing with colonoscopy-related adverse events is almost impossible.