Performance of bowel preparation quality scales in patients with Crohn's disease.

Background: The performance of bowel preparation (BP) in patients with Crohn's disease (CD) is unknown.

Aims: To evaluate the operating properties of instruments used to assess BP quality in patients with CD.

Methods: We used the Boston Bowel Preparation Scale, modified Boston Bowel Preparation Scale, Harefield Cleansing Scale, Food and Drug Administration Bowel Cleansing Assessment Scale (BCAS), and a 100-mm visual analogue scale of bowel cleanliness to assess BP quality in 50 videos from 40 patients with CD. We assessed endoscopic activity with the Simple Endoscopic Score for CD (SES-CD). Assessments were on endoscope insertion and withdrawal. Reliability was quantified using the intraclass correlation coefficient (ICC). We assessed validity by within-patient correlation between instruments and the visual analogue scale using mixed-effect models. The correlation between BP quality and SES-SD scores was assessed using Spearman's rho.

Results: Inter- and intra-rater reliability for all BP quality instruments was substantial (ICC ≥0.61) except for the Food and Drug Administration BCAS on insertion (inter-rater reliability ICC ≥0.41). The visual analogue scale had substantial inter- and almost perfect (ICC ≥0.81) intra-rater reliability. Correlation coefficients for the validity of the instruments exceeded 0.58. BP quality and endoscopic disease activity scores in the colon were negatively correlated.

Conclusion: Most existing instruments reliably assess BP quality in patients with CD. These results support the use of these instruments in clinical practice, provide a framework for scoring BP quality in CD clinical trials, and support evaluation of novel BP agents in patients with CD.