Repeat-screening colonoscopy 5 years after normal baseline-screening colonoscopy in average-risk Chinese: a prospective study.

Abstract

Although colonoscopy is considered the most accurate screening tool for colorectal neoplasm, the optimal interval of repeating a screening colonoscopy, particularly in average-risk subjects after a negative colonoscopy, is poorly defined. We determine the 5-year risk of advanced neoplasia on rescreening colonoscopy in a cohort of average-risk Chinese subjects. We invited a cohort of asymptomatic average-risk Chinese subjects (aged 55-75 years) who were recruited in our previous screening colonoscopy studies to undergo a repeat colonoscopy at the end of 5 years. The rates of advanced colorectal neoplasia at the end of 5 years in these subjects were determined according to their baseline colonoscopy findings. A total of 511 of the 620 eligible subjects underwent repeat-screening colonoscopy at the end of 5 years. Among them, 401 subjects had no baseline neoplasia (370 with no baseline polyps and 31 with hyperplastic polyps). In subjects with no baseline polyp, 24.6% were found to have at least one adenoma and 1.4% had advanced neoplasia on rescreening. The number needed to rescreen for one advanced neoplasia in subjects with no baseline polyp was 74 (95% confidence interval (CI), 32-168). The prevalence of advanced neoplasia at 5 years in subjects with baseline-advanced neoplasia was 20.7% (relative risk 19.6; 95% CI, 5.2-74.1; vs. subjects with no baseline polyp). The presence of baseline-advanced neoplasia (odds ratio (OR) 13.1; 95% CI, 4.1-41.7) and age in years (OR 1.11; 95% CI, 1.01-1.22) are two independent factors for development of advanced neoplasia at 5 years. The risk of advanced neoplasia is sufficiently low 5 years after a normal screening colonoscopy in Chinese subjects.