Abstract
Background Development of bowel preparation products has been based upon colon cleansing rating by a local endoscopist. It is unclear how bowel preparation scales perform when centrally evaluated. Aims To evaluate the reliability of bowel preparation quality scales when assessed by central readers. Methods Four central readers evaluated 52 videos in triplicate, 2 weeks apart, during the entire endoscopic procedure (insertion/withdrawal of the colonoscope) and exclusively on colonoscope withdrawal using the Boston Bowel Preparation Scale (BBPS), Chicago Bowel Preparation scale, Harefield Cleansing Scale, Ottawa Bowel Preparation Quality Scale (OBPQS), Aronchick score, a visual analogue scale, and additional items proposed in a modified Research and Development/University of California Los Angeles appropriateness process. Reliability was assessed with intraclass correlation coefficients. Results Intraclass correlation coefficients (95% confidence interval) for inter-rater reliability of the quality scales ranged from 0.51 to 0.65 (consistent with moderate to substantial inter-rater reliability) during the entire procedure. Corresponding intraclass correlation coefficients for intra-rater reliability ranged from 0.69 to 0.77 (consistent with substantial intra-rater reliability). Reliability was highest in the right colon and lowest in the left colon. No differences were observed in reliability when assessed for the procedure overall (insertion/withdrawal) relative to assessment on withdrawal alone. Conclusion All five bowel preparation quality scales had moderate to substantial inter-rater reliability. Panelists considered the Aronchick score too simplistic for clinical trials and recognized that assessment of residual fluid in the Ottawa Bowel Preparation Quality Scale was not amenable to central assessment.