Background and Aims — Colonoscopy has been demonstrated to be effective in colorectal cancer (CRC) mortality reduction, though current screening guidelines have yet to be evaluated. We assessed the protective benefit of colonoscopy within the past 10 years and whether this effect is maintained with age.
Method — We used administrative data to compare risk of CRC death (CCD) across colonoscopy utilization among a population-wide cohort comprising individuals aged 60 to 80 years (N = 1,509,423). Baseline and time-dependent colonoscopy exposure models were assessed in the context of competing “other cause deaths” (OCD). Cumulative incidence of CCD and OCD across colonoscopy exposure, over follow-up, was estimated. Relative hazards were computed by age strata (60-69 years, 70-74 years, 75+ years) and proximal and distal cancer subsites.
Results — At least one colonoscopy during 10 years before baseline was estimated to provide a 51% reduced hazard of CCD (HR, 0.49; 95% CI, 0.45-0.54) over the following 8 years. When colonoscopy was modeled as a time-dependent covariate, risk of CCD was further diminished (multivariable-adjusted HR, 0.36; 95% CI, 0.33-0.38). Stratified analyses suggested moderately attenuated CCD risk reduction among the oldest age group, however, consideration of OCD suggest this is due to competing risks. CCD risk reduction due to colonoscopy was lower for proximal cancers.
Conclusion — Colonoscopy within the past 10 years provides substantial protective benefit for average-risk individuals over 60 years. CCD risk reduction may be maintained well beyond 74 years, a common upper age limit recommended by screening guidelines.
Health care evaluation