Utilization and reproducibility of World Endoscopy Organization post-colonoscopy colorectal cancer algorithms: retrospective analysis

Abstract

Background: Colorectal cancer (CRC) diagnosed following a cancer-negative colonoscopy is termed post-colonoscopy CRC (PCCRC). In addition to calculating PCCRC rates, the World Endoscopy Organization (WEO) recommends review of individual PCCRC cases, including categorization into interval/non-interval PCCRCs, and root cause analysis to determine the most plausible explanation. We aimed to test the usability, reproducibility, and outcomes of the WEO algorithms.

Methods: All CRC cases diagnosed from January 2015 to December 2016 in a single organization were cross referenced with local endoscopy and pathology databases to identify cases of PCCRC. We assessed: 1) WEO most plausible explanation for PCCRC; and 2) WEO PCCRC interval/non-interval subtype categorization. Interobserver agreement was measured using Cohen's kappa (κ). Cases with interobserver variation underwent panel discussion to reach consensus.

Results: Among 527 patients with CRC, 48 PCCRCs were identified. A consistent most plausible explanation was found in 97 % of cases, showing almost perfect agreement (κ = 0.94). Most PCCRCs (66 %) were attributed to "possible missed lesion, prior examination adequate." Interval/non-interval categorization was consistent in 77 %, showing substantial agreement (κ = 0.67). Following panel discussion, consensus was reached in all cases. Overall, 15 % were categorized as interval and 85 % as non-interval PCCRCs (12 % type A, 31 % type B, and 42 % type C).

Conclusions: Review of PCCRC cases using WEO recommendations was performed accurately at a local level using readily available clinical information. The high number of non-interval type B PCCRCs suggests a significant proportion of PCCRCs could be avoided by better adherence to recommended surveillance intervals.