Predictors of Inadequate Bowel Preparation at Colonoscopy

Summary and Comment |
September 21, 2017

Predictors of Inadequate Bowel Preparation at Colonoscopy

  1. Douglas K. Rex, MD

Identifying predictors, like constipation, cirrhosis, or diabetes, can be used to triage patients to more-effective preparation regimens.

  1. Douglas K. Rex, MD

To identify risks for inadequate bowel preparation at colonoscopy, researchers conducted a systematic review and meta-analysis comprising 67 studies with more than 75,000 participants.

Predictors of inadequate bowel preparation with clinically important odds ratios (>1.5) were constipation (OR, 2.0), cirrhosis (3.4), diabetes (1.8), stroke or dementia (2.1), opioids (1.7), and tricyclic antidepressants (2.6 in women and 1.4 in men). Age, male gender, prior abdominal surgery, and hypertension had statistically significant predictive value but odds ratios <1.5. Among 10 studies examining lower education level as a predictor, after excluding 2 studies showing that lower educational level was associated with better bowel preparation, the pooled odds ratio was 1.5.


The usual approach to applying patient predictors such as those identified in this study is to triage patients with one or more predictors to a more-effective preparation regimen, such as a 4-liter polyethylene glycol–electrolyte lavage solution in split doses (or even additional preparation), and to triage patients without predictors to low-volume preparations. Alternatively, some patients may benefit more from increased educational efforts or navigation. In addition to these factors, we use a high-volume preparation in patients with segmental colon resection, as this factor has been associated with increased risk for inadequate bowel cleansing in two studies, and this is consistent with my experience.

Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.

Editor Disclosures at Time of Publication

  • Disclosures for Douglas K. Rex, MD at time of publication Consultant/Advisory board Olympus Corporation America; Boston Scientific Speaker’s bureau Boston Scientific Grant/Research support Medtronic; Boston Scientific; Colonary Solutions; Paion Medical; Medivators; Braintree Laboratories Editorial boards World Journal of Gastroenterology; The Journal of Clinical Gastroenterology; Techniques in Gastrointestinal Endoscopy; Gastroenterology & Hepatology; Expert Review of Gastroenterology & Hepatology; Medscape Gastroenterology; World Journal of Gastrointestinal Pharmacology and Therapeutics; Annals of Gastroenterology & Hepatology; World Journal of Gastrointestinal Oncology; Comparative Effectiveness Research; Journal of Anesthesia & Clinical Research; Gastroenterology; World Journal of Gastrointestinal Pathophysiology; Gastroenterology Research and Practice; GI & Hepatology News; Gastroenterology Report; Clinical Epidemiology Reviews; JSM Gastroenterology and Hepatology; GI Journal Watch; Austin Journal of Gastroenterology; World Journal of Gastrointestinal Pharmacology & Therapeutics Leadership positions in professional societies American Society for Gastrointestinal Endoscopy (Councilor); US Multi-Society Task Force (AGA, ACG, ASGE) (Chair)


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