Assessing the impact of the 2018 National Health and Medical Research Council polyp surveillance guidelines on compliance with surveillance intervals at two public hospitals.

Background: Several studies have highlighted poor compliance with surveillance colonoscopy guidelines. The National Health and Medical Research Council (NHMRC) guidelines were revised in 2018 and were more complex than the previous iteration (2011). The aim of this study was to determine the impact of 2018 NHMRC polyp surveillance guidelines on compliance with colonoscopy surveillance intervals.

Methods: A multicentre retrospective clinical audit was conducted between January 2020 and February 2021. Patients awaiting a colonoscopy for polyp surveillance at two public tertiary care hospitals in South Australia were included. Compliance rates of recommended polyp surveillance colonoscopy intervals after implementation of 2018 NHMRC guidelines were compared with 2011 NHMRC guidelines. The projected impact on colonoscopy bookings of the change in guideline intervals was modelled to 5 and 10 years, factoring in differences in compliance.

Results: Of 3996 patients awaiting colonoscopy services at two public hospitals in South Australia, 1984 patients (60% male, median age 61 years) were waitlisted for polyp surveillance. Overall compliance with surveillance guidelines was >60%. Implementation of the 2018 NHMRC guidelines significantly reduced compliance from 65.8% (2011 guidelines) to 50.8% (2018) (χ <0.001, OR 0.5). Modelling projections to 5 and 10 years demonstrated that application of the 2018 guidelines significantly increases the projected number of colonoscopy bookings per year.

Conclusion: The revised 2018 NHMRC guidelines have resulted in significantly poorer compliance post-implementation, possibly due to their increased complexity. This has potential to increase the surveillance colonoscopy waiting list burden.