Evaluation of Polyp Detection Rates Following Changes in Colonoscopy Surveillance Intervals

In 2020, the U.S. Multi-Society Task Force (USMSTF) extended the surveillance interval for patients with 1-2 small (< 10 mm) tubular adenomas from 5-10 years to 7-10 years following a high-quality baseline colonoscopy. Whether longer intervals affect polyp yield at repeat colonoscopy remains unclear.

From 9,300 patients who underwent colonoscopy in 2015 within the MedStar Health system, we identified individuals with 1-2 small tubular adenomas who subsequently completed surveillance colonoscopy. Patients were identified using ICD-10 codes and manual chart review. Extracted variables included demographics, BMI, smoking status, NSAID use, race/ethnicity, family history of colorectal cancer (CRC), Boston Bowel Preparation Score, withdrawal time, pathology results, and surveillance interval. Patients were stratified into two groups: < 7 years vs ≥ 7 years between baseline and repeat colonoscopy. Primary outcomes were the detection of any polyp and neoplastic polyps (precancerous, advanced adenoma, SSL etc.). Group differences were evaluated using Wilcoxon rank-sum and Fisher's exact tests.

A total of 399 patients met the inclusion criteria (326 < 7 years; 73 ≥ 7 years). Median follow-up time was 4.4 years vs 8.0 years, respectively (p < 0.001). Baseline characteristics-including age, gender, race/ethnicity, BMI, smoking status, NSAID use, and family history of CRC-were similar between groups, with no statistically significant differences (all p > 0.05). Procedure quality indicators such as Boston Bowel Preparation Score and withdrawal time, were also comparable. At repeat colonoscopy, patients with ≥ 7-year intervals had numerically higher rates of any polyp detection (67% vs 57%; p = 0.15) and neoplastic polyps (55% vs 48%; p = 0.30), though these differences were not statistically significant.

Among patients with 1-2 small, low-risk tubular adenomas, extending the surveillance colonoscopy interval to ≥ 7 years did not significantly increase the detection of neoplastic polyps compared with earlier surveillance. Given the similar baseline characteristics and quality metrics between interval groups, these findings support the safety of the 2020 USMSTF recommendation for a 7-10 year surveillance interval. Larger studies may clarify whether delayed surveillance meaningfully affects advanced neoplasia risk.