Selected comorbidities increases the likelihood of an incomplete colonoscopy during colorectal cancer screening.

Objective: The risk of incomplete colonoscopy is associated with demographic factors and general comorbidity. However, focus on specific comorbidities is limited. This study aimed to investigate the association between selected comorbidities and incomplete colonoscopy in colorectal cancer (CRC) screening.

Methods: This register-based study included 71,973 Danish screening participants, undergoing colonoscopy after positive fecal immunochemical test. The selected comorbidities were divided into hematological disease, endocrine disease (nondiabetes), endocrine disease (diabetes related), upper gastrointestinal (GI) disease, lower GI disease, other diseases of digestive system, hepatobiliary and pancreatic (HBP) disease, CRC, intraabdominal cancer (except CRC), and mental disease. Outcomes were incomplete colonoscopy due to poor bowel preparation and other reasons. Multivariate logistic regression models were applied.

Results: Of 5,428 (7.5%) incomplete colonoscopies, 2,625 (3.6%) were due to poor bowel preparation and 2,803 (3.9%) due to other reasons. Individuals with specific comorbidities were compared to those without, exhibiting varying odds ratios (OR) for incomplete colonoscopy. For poor bowel preparation, ORs were 1.20 (95%CI: 1.04;1.39), 1.43 (95%CI: 1.30;1.56), 1.86 (95%CI: 1.66;2.09), 1.27 (95%CI: 1.12;1.43), and 1.64 (95%CI: 1.47;1.83) for hematological, endocrine (nondiabetes), endocrine (diabetes related), HBP, and mental disease, respectively, and 1.29 (95%CI: 1.09;1.52) for intraabdominal cancer (except CRC). Incomplete colonoscopies due to other reasons showed ORs of 1.24 (95%CI: 1.08;1.43), 1.18 (95%CI: 1.03;1.36), 1.19 (95%CI: 1.05;1.35), and 1.30 (95%CI: 1.15;1.47) for hematological, endocrine (diabetes related), HBP, and mental disease, respectively, and 1.35 (95%CI: 1.15;1.60) for intra-abdominal cancer (except CRC).

Conclusion: Participants with specific comorbidities had significantly higher probability of having an incomplete colonoscopy, suggesting that certain comorbidities could be used prospectively as a predictive factor.