Outcomes of patients with delayed surveillance colonoscopy

Surveillance colonoscopy has been shown to be an effective tool for prevention of colorectal cancer (CRC) in high-risk populations, if adhered to.

To discover the sequelae of late surveillance in a cohort of patient's overdue for colonoscopy.

We conducted a retrospective cohort study on all patients from the Bay of Plenty District Health Board region, New Zealand, placed on the colonoscopy surveillance waitlist from 2006 onwards who had their procedure completed between 1 November 2016 and 31 January 2018. Patients with overdue surveillance, defined as done later than 90 days after the recommended due date, were compared with patients who were done either early or on time.

A total of 786 patients was recorded as overdue for surveillance colonoscopy and 386 were completed early or on time. The median time overdue was 22 months. Three (0.4%) cases of CRC were found in overdue patients compared with four (1%) cases for those done on time (adjusted P = 0.24). There were 86 (11%) advanced adenomas (AA) in patients overdue compared with 27 (7%) in those not overdue (odds ratio (OR) 1.6; 95% confidence interval (CI) 1.0-2.5; P = 0.04). Surveillance of 180 high-risk post-polypectomy patients identified 2 CRC and 8/43 AA in those overdue compared with no CRC and 9/137 AA (18.6% vs 6.6%; OR 1.79; 95% CI 1.07-2.0; unadjusted P = 0.03) in those done on time.

While overdue surveillance is not predictive of increased CRC, it is associated with an increase in expected number of AA, particularly in patients having surveillance for previous high-risk polypectomy.