A new study has proposed the number of adenomas per colonoscopy (APC) as a new quality-control measure for colonoscopy.^1.2

Data for the study were sourced from the New Hampshire Colonoscopy Registry (NHCR) and evaluated 9023 screening colonoscopies performed by 138 endoscopists. Patients had a minimum one follow-up event, either a colonoscopy or a colorectal cancer (CRC) diagnosis, which occurred 6-60 months after the initial examination. Post-colonoscopy CRC (PCCRC) was defined as either any CRC diagnosed between 6 and 36 months after an index exam or those diagnosed between 6 and 60 months after an index exam. The exclusion criteria included any CRC diagnosed at index or within 6 months, inflammatory bowel disease (IBD), genetic syndromes and incomplete exams.

Three quality measures were examined for their association with PCCRC: APC of 0.4, APC of 0.6 and adenoma detection rate (ADR) of 25%.Eighty-two cases of PCCRC were diagnosed from 6 to 60 months after the first examination. Of these 82, 50 were diagnosed between 6 and 36 months.

A significant correlation was seen between all the three selected quality measures and reductions in PCCRC, especially for the 6-36 month period. However, the protection was greater with the higher APC of 0.6, with a decline in PCCRC by 71% at 6-36 months and 61% at 6-60%. The corresponding figures were 63% and 53% for APC of 0.4, and 62% and 42% for the ADR of 25%. A similar trend was observed for PCCRC diagnosed at the first follow-up event. “An APC of 0.6 was associated with respective reductions of 79% and 65% for the shorter and longer period, compared with 64% and 57% for the lower APC, and 67% and 49% for ADR”.

This study has demonstrated an inverse association between the number of adenomas detected per colonoscopy and occurrence of post-colonoscopy colorectal cancer. Higher the APC, lower the chances of CRC after colonoscopy; in this study APC of 0.6 (hazard ratio; HR = 0.29) was more protective than an APC of 0.4 (HR = 0.37). Hence, APC can be used as a quality measure for colonoscopy and underscores the need to be diligent in looking for more adenomas, as many as possible during screening colonoscopy, even if one has been detected.

References1. Anderson J, et al. Mean adenomas per colonoscopy is inversely associated with post colonoscopy colorectal cancers: data from the New Hampshire Colonoscopy Registry validating this quality measure. Abstract S545. Am J Gastroenterol. 2021 October;116(2):p S249. doi: 10.14309/01.ajg.0000774656.32315.412. Tracking adenomas per colonoscopy promising as quality measure. Medscape Oct 28, 2021.