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What Level of Bowel Prep Quality Requires Early Repeat Colonoscopy: Systematic Review and Meta-Analysis of the Impact of Preparation Quality on Adenoma Detection Rate

Clark, Brian T MD1; Rustagi, Tarun MD1; Laine, Loren MD1, 2

American Journal of Gastroenterology: November 2014 - Volume 109 - Issue 11 - p 1714–1723
doi: 10.1038/ajg.2014.232

OBJECTIVES: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.

1 Section of Digestive Diseases, Yale University School of Medicine, New Haven, Connecticut, USA

2 VA Connecticut Healthcare System, West Haven, Connecticut, USA

Correspondence: Loren Laine, MD, Section of Digestive Diseases, Yale University School of Medicine, P.O. Box 208019, New Haven, Connecticut 06520-8019, USA. E-mail:

SUPPLEMENTARY MATERIAL accompanies this paper at

Received 9 February 2014; accepted 3 June 2014

published online 19 August 2014

© The American College of Gastroenterology 2014. All Rights Reserved.
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