Temporal trends in postcolonoscopy colorectal cancer rates in 50- to 74-year-old persons: a population-based study

Background and aims: Colorectal cancers (CRCs) diagnosed between 6 and 36 months after colonoscopy, termed postcolonoscopy CRCs (PCCRCs), arise primarily due to missed or inadequately treated neoplasms during colonoscopy. Introduction of multiple quality indicators and technological advances to colonoscopy practice should have reduced the PCCRC rate over time. We assessed temporal trends in the population rate of PCCRC as a measure of changing colonoscopy quality.

Methods: We conducted a population-based retrospective cohort study of persons aged 50 to 74 years without advanced risk factors for CRC who underwent complete colonoscopy in Ontario, Canada between 1996 and 2010. We defined the PCCRC rate as the proportion of individuals diagnosed with CRC within 36 months of colonoscopy that had PCCRC. We compared age-adjusted and sex-adjusted rates of PCCRC over time based on 3 periods (1996-2001, 2001-2006 and 2006-2010) and assessed the independent association between time period and PCCRC risk through multivariable regression, with respect to all PCCRCs, proximal PCCRC and distal PCCRC.

Results: There was a marked increase in colonoscopy volumes over the study period, particularly in younger age groups and non-hospital settings. Among 1,093,658 eligible persons the PCCRC rate remained stable at approximately 8% over the 15-year study period. The adjusted odds of PCCRC, distal PCCRC and proximal PCCRC, comparing the 2006 to 2010 period with the 1996 to 2001 period, were 1.14 (95% confidence interval [CI], 1.0-1.31), 1.11 (95% CI, 0.91-1.34), and 1.14 (95% CI, 0.94-1.38), respectively. Temporal trends in PCCRC risk did not differ by endoscopist specialty or institutional setting after covariate adjustment.

Conclusion: The PCCRC rate in Ontario has remained consistently high over time. Widespread initiatives are needed to improve colonoscopy quality.