Superiority of a Procedure-Related Model for Predicting Inadequate Bowel Preparation in Patients Undergoing Colonoscopy: A Multicenter Prospective Study

Background: Inadequate bowel preparation (BP) is a major contribution to inefficacy of colonoscopy. Three models based on patient-related factors have been developed to predict inadequate BP. However, the performance of the models seems suboptimal. This study aimed to develop a novel procedure-related model and compare it with the available patient-related models. Methods: Patients receiving standard BP were prospectively enrolled from 5 endoscopic centers in China. Patient-related and procedure-related factors for inadequate BP (defined by segmental Boston Bowel Preparation Scale score <2) were identified by logistic regression. A procedure-related model was derived and internally validated in 906 patients. The comparisons of models were assessed by discrimination and calibration. The procedure-related model was also externally validated. Results: Several patient-related factors (male and American Society of Anesthesiologists Physical Status Classification System score ≥3) and procedure-related factors (starting-to-defecation interval ≥3h, preparation-to-colonoscopy interval ≥6h and poor last rectal effluent) were found to be independent associated with inadequate BP (all p<0.05). C-statistics was 0.81 (95% CI 0.76-0.86) for the procedure-related model in the training cohort (n=604), significantly higher than those of three patient-based models (0.61 for Hassan’s, 0.61 for Dik’s and 0.58 for Antonio’s, respectively; all p <0.05). Similar results were observed in the validation cohort (n=302). The procedure-related model was also externally validated in another 606 patients with C-index of 0.80 (95% CI 0.76-0.84). Calibration curves showed close or fair agreement in the procedure-related model (R2=0.315 in the training cohort and 0.279 in the validation cohort). Conclusion: A new procedure-related model (consisting of starting-to-defecation interval ≥3h, preparation-to-colonoscopy ≥6h and poor last rectal effluent) was developed and performed better than three available patient-related models. This easy-to-use model may be a useful decision-support tool on individualized plans in patients undergoing BP.Trial Registration: This study was registered with ClinicalTrials.gov (NCT04101097 and NCT04325139).Funding Statement: This work supported in part by the National Natural Science Foundation of China (81970557 and 82003152).Declaration of Interests: The authors declare no conflicts of interest.Ethics Approval Statement: The study protocol was approved by the Ethics Committee of all participated centers. Written informed consent was obtained from all enrolled patients. The trial conformed to the ethical guidelines of the Declaration of Helsinki and Good Clinical Practice (GCP) as well as obeyed local laws.