Current guidelines recommend early repeat colonoscopy when bowel preparation quality is inadequate, defined as inability to detect polyps >5 mm, but no data link specific bowel preparation categories or scores to this definition. Nevertheless, most physicians use a shortened screening/surveillance interval in patients with intermediate-quality preparation. We determined whether different levels of bowel preparation quality are associated with differences in adenoma detection rates (ADRs: proportion of colonoscopies with ≥1 adenoma) to help guide decisions regarding early repeat colonoscopy—with primary focus on intermediate-quality preparation.
MEDLINE and Embase were searched for studies with adenoma or polyp detection rate stratified by bowel preparation quality. Preparation quality definitions were standardized on the basis of Aronchick definitions (excellent/good/fair/poor/insufficient), and primary analyses of ADR trichotomized bowel preparation quality: high quality (excellent/good), intermediate quality (fair), and low quality (poor/insufficient). Dichotomized analyses of adequate (excellent/good/fair) vs. inadequate (poor/insufficient) were also performed.
Eleven studies met the inclusion criteria. The primary analysis, ADR with intermediate- vs. high-quality preparation, showed an odds ratio (OR) of 0.94 (0.80–1.10) and absolute risk difference of –1% (−3%, 2%). ADRs were significantly higher with both intermediate-quality and high-quality preparation vs. low-quality preparation: OR=1.39 (1.08–1.79) and 1.41 (1.21–1.64), with absolute risk increases of 5% for both. ADR and advanced ADR were significantly higher with adequate vs. inadequate preparation: OR=1.30 (1.19–1.42) and 1.30 (1.02–1.67). Studies did not report other relevant outcomes such as total adenomas per colonoscopy.
ADR is not significantly different with intermediate-quality vs. high-quality bowel preparation. Our results confirm the need for early repeat colonoscopy with low-quality bowel preparation, but suggest that patients with intermediate/fair preparation quality may be followed up at standard guideline-recommended surveillance intervals without significantly affecting quality as measured by ADR.