Detection rate and proximal shift tendency of adenomas and serrated polyps: a retrospective study of 62,560 colonoscopies

The purpose of this study is to estimate the detection rates of adenomas and serrated polyps and to identify proximalization and associate risk factors in patients from Southern China.

Consecutive patients undergoing colonoscopy from 2004 to 2013 in Guangzhou were included. The proportions of proximal adenomas to advanced adenomas and serrated polyps were compared and potential predictors were evaluated.

Colonoscopies (n = 62,560) were performed, and 11,427 patients were diagnosed with polyps. Detection rates for adenomas, hyperplastic polyps, and serrated adenomas were 12.0, 2.5, and 0.2 patients per 100 colonoscopies. When comparing the 1st (2004-2008) to the 2nd period (2009-2013), adenoma and serrated polyp detection in proximal and distal colon both increased significantly (proximal colon [adenoma 3.9 vs. 6.1 patients/100 colonoscopies, P < 0.001; serrated polyp 0.4 vs. 1.1 patients/100 colonoscopies, P < 0.001]; distal colon [adenoma 6.6 vs. 7.2 patients/100 colonoscopies, P = 0.003; serrated polyp 1.2 vs. 2.4 patients/100 colonoscopies, P < 0.001]). Advanced adenoma detection increased over these two periods only in proximal colon (1st vs. 2nd period: 1.5 vs. 2.4 patients/100 colonoscopies, P < 0.001), not the distal colon (P = 0.114). Multivariate analyses showed that diagnostic period was an independent predictor for adenoma proximalization (OR = 1.36, 95% CI 1.25-1.48, P < 0.001), but not for advanced adenomas (P = 0.117) or serrated polyps (P = 0.928).

Adenomas and serrated polyps were increasingly detected throughout the colon, whereas advanced adenomas were only in proximal colon. A proximal shift tendency detected by colonoscopy was observed for adenomas, but not advanced adenomas or serrated polyps, in Southern China. The screening for proximal polyps should be emphasized and colonoscopy might be a preferred initial screening tool.