Minimal benefit of earlier-than-recommended repeat colonoscopy among US Medicare enrollees following a negative colonoscopy

Abstract

Background A large proportion of US Medicare beneficiaries undergo earlier-than-recommended follow-up colonoscopies after negative screening colonoscopy. Such practice entails substantial cost and added risk. Aims To compare the risk of colorectal cancer (CRC) associated with varying follow- up colonoscopy intervals following a negative colonoscopy, and to determine whether the potential benefit of a shorter colonoscopy follow-up interval would differ by gender. Methods We conducted a weighted cohort study using the Surveillance, Epidemiology and End Results-Medicare linked database (1991-2006) among 932 370 Medicare enrollees who are representative of the entire US elderly population. We compared the cumulative incidence of CRC among patients who underwent follow-up colonoscopies at different intervals following a negative colonoscopy. The primary outcome was incident CRC. Results The eligible study cohort (n = 480 864) included 106 924 patients who underwent ≥1 colonoscopy. Men were more likely to require polypectomy during their initial colonoscopy than women. Compared to the recommended 9-10 year follow- up colonoscopy interval, an interval of 5-6 years was associated with the largest CRC cumulative risk reduction [i.e. 0.17% (95% CI: 0.009-0.32%)]. The magnitude of risk reduction associated with shorter colonoscopy follow-up intervals was not significantly different between men and women. Conclusions Among elderly individuals who undergo a negative colonoscopy, the magnitude of reduction in the cumulative CRC risk afforded by earlier-than-recommended follow-up colonoscopy is quite small, and probably cannot justify the risk and cost of increased colonoscopy frequency. In addition, there are insufficient differences between men and women to warrant gender-specific recommendations.