Time of Day As a Risk Factor for Incomplete Colonoscopy: An Australian Tertiary Referral Hospital Experience

Abstract

Background: One time colonoscopy with polypectomy has a significant reduction on expected colorectal cancer mortality. Identifying and addressing the factors that affect quality of colonoscopy are paramount. Risk factors for incomplete colonoscopy including age, gender, bowel preparation adequacy and diverticular disease have been characterised. Whether having an afternoon vs. morning colonoscopy is an independent risk for not achieving caecal intubation is less clearly defined. Questions have been raised wether proceduralist fatigue or just inadequacy of bowel preparation for afternoon procedures accounts for decreased caecal intubation rates. Methods: Retrospective single centre study of all colonoscopies performed at the John Hunter Hospital Australia from 1/1/2006 until 31/12/2006. Results: A total of 1367 colonoscopies performed. 83 colonoscopies were excluded due to patients having previous colon resection. A further 14 colonoscopies were excluded as the reason for termination of colonoscopy was obstructing tumour. There were 644 morning colonoscopies and 626 afternoon colonoscopies. There were 150 unsuccessful colonoscopies giving a caecal intubation rate of 88.1%. 43.3% of unsuccessful colonoscopies were in the morning verse 56.7% after midday (p < 0.05). 42.7% of unsuccessful colonoscopies only extended to the sigmoid or descending colon. 64.7% unsuccessful colonoscopies were in women and 35.3% in males (p < 0.05). Poor bowel preparation was reported in 41.3% of unsuccessful colonoscopies vs. 13.1% of successful colonoscopies (p < 0.05). 25% of unsuccessful colonoscopies vs. 26% successful colonoscopies had a diagnosis of diverticular disease.(P > 0.05). Multivariate analysis demonstrated that the independent risk factors for unsuccessful colonoscopy were poor bowel preparation, gender, and time of day of procedure. There was no significant interaction between these variables (P > 0.05), suggesting that time of day is an independent risk factor for failed colonoscopy. Conclusion: Time of day is an independent risk factor for not achieving caecal intubation at colonoscopy. Priority booking of colonoscopy to the beginning of procedure lists may improve this outcome and warrants prospective investigation in the Australian setting.