Objectives: Although colonoscopy use has increased in the United States and Canada since the early 1990s, it is unclear whether this has been associated with benefit at the population level. Our objective was to evaluate the association between regional colonoscopy rates and death from colorectal cancer (CRC).
Methods: We conducted a natural experiment involving a 14-year follow-up of a cohort of all men and women 50-90 years of age living in Ontario on 1 January 1993 exposed to different intensities of colonoscopy use. Each member of the study cohort was assigned to a region each year, on the basis of his/her residence. Each individual was followed up through 31 December 2006; age- and sex-standardized CRC incidence rates were calculated and all CRC deaths were identified. Each year, for each region, the rate of colonoscopies performed on persons 50-90 years of age, per 1,000 population 50-90 years of age, living in the region, was calculated. Multivariable cox proportional hazards models were used to evaluate the association between colonoscopy rate and death from CRC, adjusting for age, sex, comorbidity, income, and location of residence (urban/rural).
Results: The study cohort comprised 2,412,077 persons 50-90 years of age. The mean age was 64 years, and 53.7% were women. Colonoscopy rates increased in all regions during 1993-2006. The increased rate of complete colonoscopy was inversely associated with death from CRC. For every 1% increase in complete colonoscopy rate, the hazard of death decreased by 3%.
Conclusions: Increased colonoscopy use was associated with mortality reduction from CRC at the population level.