Validation of Australian and Victorian Guidelines for Colonoscopy Triage

Background: Managing the growing demand for colonoscopies is challenging.

Aims: To assess the diagnostic performance of National and Victorian colonoscopy triage guidelines and potential redistribution of triage categories.

Methods: This is a diagnostic validation study comparing colonoscopy triage guidelines against a reference colonoscopy dataset. Participants were a reference dataset of 2378 colonoscopies from 1 October 2014 to 30 June 2016. Comparison with triage categorisation determined using National Cancer Council Australia guidelines; Victorian triage guidelines; Optimal Cancer Care Pathways recommendations. Main outcome measures were as follows: (i) proportion of colonoscopies assigned to each triage category; (ii) detection rate (proportion of cancers assigned to triage Category 1); and (iii) conversion rate (proportion of triage Category 1 colonoscopies that diagnose a cancer).

Results: After adjusting for data absent in referrals, the National and Victorian guidelines reduced the proportion of Category 1 colonoscopies compared with the reference triage (National 76.3% vs 58.6%; 95% CI for difference 15.0-20.3%, P < 0.0001. Victorian 76.3% vs 66.3%; 95% CI for difference 7.4-12.6%, P < 0.0001). Victorian guidelines were associated with the highest detection rate (91.4%) and a conversion rate of 5.4% although the number of cancers limited the power to detect significant differences on these metrics. There was a higher proportion of unclassifiable colonoscopies using the National guidelines than the Victorian ones due to their focus on symptomatic indications.

Conclusions: The Victorian guidelines could reduce the proportion of Category 1 colonoscopies by 10% without reducing conversion or detection rates. This would require improvements in the quality of referrals and ordering faecal occult blood tests in 6% of symptomatic patients.