Effectiveness of Screening Colonoscopy to Prevent Colorectal Cancer Among Medicare Beneficiaries Aged 70 to 79 Years

Abstract

Background No randomized controlled trials of screening colonoscopies have been completed, and ongoing trials exclude subjects aged 75 years or older. The Medicare program, however, reimburses screening colonoscopies without an upper age limit. Objective To evaluate the effectiveness and safety of screening colonoscopy to prevent colorectal cancer in individuals aged 70–74 and 75–79. Design Setting Large-scale, population-based, prospective study. The observational data was used to emulate a target trial with 2 arms: colonoscopy screening and no screening. Participants 1,355,692 Medicare individuals (2004–2012) aged 70–79 at average risk for CRC who used Medicare preventive services and had no previous diagnostic or surveillance colonoscopies in the previous five years. Measurements Eight-year risk of CRC and 30-day risk of adverse events. Results In the 70–74 age group, the 8-year risk of CRC (95% CI) was 2.19% (2.00, 2.37) in the colonoscopy screening arm and 2.62% (2.56, 2.67) in the no screening arm; absolute risk difference −0.42% (−0.24, −0.63). In the 75–79 age group, the 8-year risk of CRC (95% CI) was 2.84% (2.54, 3.13) in the colonoscopy screening arm and 2.97% (2.92, 3.03) in the no screening arm; risk difference −0.14% (−0.41, 0.16). The excess 30-day risk of any adverse event in the colonoscopy arm was 5.6 adverse events per 1,000 individuals (95% CI 4.4–6.8) in the 70–74 age group and 10.3 adverse events per 1,000 individuals (95% CI 8.6–11.1) in the 75–79 group. Limitations CRC-specific mortality was not available, but we studied CRC incidence and stage at diagnosis. Conclusions Our findings suggest a modest benefit of screening colonoscopy for the prevention of CRC in beneficiaries aged 70–74 years, and a smaller benefit in older beneficiaries. The risk of adverse events was low, but greater among older individuals.