Patient- and procedure-related factors affecting proximal and distal detection rates for polyps and adenomas: results from 1603 screening colonoscopies.

Background: Screening colonoscopy is less effective in reducing the incidence of proximal compared to distal colorectal cancer, presumably because of missed adenomas and advanced lesions during endoscopy. Thus, effectiveness and success of colorectal cancer (CRC) screening programs depend decisively on the quality of the endoscopic procedures.

Methods: A retrospective analysis of 1603 average risk screening colonoscopies to calculate and to identify determinants of separate detection rates for proximally and distally located polyps, adenomas, and advanced adenomas was performed.

Results: 56.1 % of 1603 individuals included were men, and the mean age was 60.2 ± 10.2 years. Distal detection rates were markedly higher compared to proximal detection rates for polyps (40.9 vs. 23.8 %), adenomas (21.3 vs. 16.2 %), and advanced adenomas (4.0 vs. 2.0 %). A gradual increase in detection rates with increasing age was found for proximal and distal localization. Gender difference was also seen for polyps and adenomas, but not for advanced adenomas. In multivariate analysis, age <65.0 years and female gender were independently associated with a lower separate polyp detection rate (PDR) and adenoma detection rate (ADR). The use of propofol was the only procedure-related variable significantly associated with higher polyp detection rate.

Conclusion: Since age and gender affect detection rates of proximally and distally located polyps and adenomas, the requirement of a specific gender-related limit in total detection rates may be insufficient as a quality indicator for screening colonoscopies.