Validation of Australian and Victorian guidelines for colonoscopy triage

Managing the growing demand for colonoscopies is challenging.

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

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).

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.

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.