Timing Intervals and Frequency of Adenoma Surveillance Colonoscopies in Central Queensland, Australia

The presence of colonic adenomatous polyps is a risk factor for colorectal cancer. Australian Guidelines changed in 2019 so that the surveillance colonoscopy intervals and polyp risk stratification were changed to reflect evidence available. The purpose of this research was to understand compliance with the Guidelines and implications for the health system.

Using routine hospital administrative datasets, all polyp surveillance colonoscopies performed from January 2018 to September 2020 in three government-funded hospitals in Central Queensland, Australia, were analysed. Colonoscopy intervals were calculated and compared with national recommendations. 'Early surveillance' was defined as greater than 6 months earlier than recommended. Logistic regression analyses were used to assess early surveillance or not, adjusted for potential confounding. Interval cancer and adenoma detection rates were also examined.

Surveillance colonoscopies were performed for 294 patients with low-risk polyps, 20 with intermediate-risk polyps, 321 with high-risk polyps and 12 with very high-risk polyps during the study period (total n = 647). Early surveillance occurred in 566 (87.5%). The overall interval cancer rate was 0.9% (6/647), and adenoma detection rates were 62.2% (357/574) before the change of guidelines and 79.1% (53/67) after the change. No examined demographic or clinical factors were associated with early surveillance.

Despite outstanding and high-quality colonoscopy services being provided, higher than recommended colonoscopy surveillance was identified in the regional public hospitals in Central Queensland. Hospital processes should be improved to ensure appropriate intervals between procedures to avoid using scarce healthcare resources.