A Novel Model to Predict Inadequate Bowel Preparation Prior to Colonoscopy Incorporating Patients’ Reactions to Drinking the Laxative

Daniela Malkin, Daniel L. Cohen, Vered Richter, Eran Ariam, Sergei Vosko, Haim Shirin, Anton Bermont*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Background and Aims: Prior studies have identified predictors of inadequate preparation with limited success. We aimed to build a model that could predict the likelihood of inadequate preparation by also including factors related to the patient’s reaction to drinking the laxative preparation. Methods: Demographic, clinical, and preparation-related data were prospectively collected on patients undergoing colonoscopy. An inadequate preparation was defined as a Boston Bowel Preparation Scale < 6. Statistical analyses were performed to identify predictors of inadequate preparation and create a predictive model. Results: 324 patients were included (age 67 +/− 14 years, 52% male). 77 (23.7%) had inadequate preparations. Diabetes (p < 0.001), cerebrovascular accident (CVA) (p < 0.001), incomplete prep consumption (p = 0.007), high school level education and above (p < 0.001), use of Bisacodyl (p = 0.005), >10 bowel movements (p = 0.02), and use of Sodium Picosulfate or low-volume polyethylene glycol (PEG) solution (2L) compared to PEG 3L (p < 0.001) were significant variables. In a multivariate analysis, prior CVA increased the risk for inadequate preparation (OR = 4.8, CI 1.6–14.5), whereas high school level education and above (OR = 0.4, CI 0.2–0.8), consumption of Bisacodyl (OR = 0.4, CI 0.2–0.8), >10 bowel movements (OR = 0.5, CI 0.3–0.9), and use of Sodium Picosulfate (OR = 0.5, CI 0.3–0.9) decreased the risk for inadequate prep. Using these, a predictive model for patients likely to have an inadequate colon preparation was created with an area under the curve of 0.74 (35% sensitivity, 90% specificity at a cutoff point of 39%). Conclusion: Given the low sensitivity, this predictive model does not appear ready for clinical use. However, due to its high specificity, it may be helpful in high-risk, sicker populations by preventing inadequately prepped procedures.

Original languageEnglish
Article number7335
JournalJournal of Clinical Medicine
Issue number23
StatePublished - Dec 2023
Externally publishedYes


  • bowel preparation
  • colonoscopy
  • inadequate preparation


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