The Boston bowel preparation scale: a valid and reliable instrument for colonoscopy-oriented research

Abstract

Background: Few bowel-preparation rating scales have been validated. Most scales were intended for comparing oral purgatives and fail to account for washing and/or suctioning by the endoscopist. This limits their utility in studies of colonoscopy outcomes, such as polyp-detection rates.

Objective: To develop a valid and reliable scale for use in colonoscopy outcomes research.

Setting: Academic medical center.

Methods: We developed the Boston bowel preparation scale (BBPS), a 10-point scale that assesses bowel preparation after all cleansing maneuvers are completed by the endoscopist. We assessed interobserver and intraobserver reliability by using video footage of colonoscopies viewed on 2 separate occasions by 22 clinicians. We then applied the BBPS prospectively during screening colonoscopies and compared BBPS scores with clinically meaningful outcomes, including polyp-detection rates and procedure times.

Results: The intraclass correlation coefficient (a measure of interobserver reliability) for BBPS scores was 0.74. The weighted kappa (a measure of intraobserver reliability) for scores was 0.77 (95% CI, 0.66-0.87). During 633 screening colonoscopies, the mean (SD) BBPS score was 6.0 +/- 1.6. Higher BBPS scores (> or =5 vs <5) were associated with a higher polyp-detection rate (40% vs 24%, P < .02). BBPS scores were inversely correlated with colonoscope insertion (r = -0.16, P < .003) and withdrawal (r = -0.23, P < .001) times.

Limitations: Single-center study.

Conclusions: The BBPS is a valid and reliable measure of bowel preparation. It may be well suited to colonoscopy outcomes research because it reflects the colon's cleanliness during the inspection phase of the procedure.

Figures

Figure 1

The Boston Bowel Preparation Scale (BBPS). A, segment score 0: unprepared colon segment with mucosa not seen due to solid stool that cannot be cleared. B, segment score 1: portion of mucosa of the colon segment seen, but other areas of the colon segment not well seen due to staining, residual stool and/or opaque liquid. C, segment score 2: minor amount of residual staining, small fragments of stool and/or opaque liquid, but mucosa of colon segment seen well. D, segment score 3: entire mucosa of colon segment seen well with no residual staining, small fragments of stool and/or opaque liquid

Figure 1

The Boston Bowel Preparation Scale (BBPS). A, segment score 0: unprepared colon segment with mucosa not seen due to solid stool that cannot be cleared. B, segment score 1: portion of mucosa of the colon segment seen, but other areas of the colon segment not well seen due to staining, residual stool and/or opaque liquid. C, segment score 2: minor amount of residual staining, small fragments of stool and/or opaque liquid, but mucosa of colon segment seen well. D, segment score 3: entire mucosa of colon segment seen well with no residual staining, small fragments of stool and/or opaque liquid

Figure 1

The Boston Bowel Preparation Scale (BBPS). A, segment score 0: unprepared colon segment with mucosa not seen due to solid stool that cannot be cleared. B, segment score 1: portion of mucosa of the colon segment seen, but other areas of the colon segment not well seen due to staining, residual stool and/or opaque liquid. C, segment score 2: minor amount of residual staining, small fragments of stool and/or opaque liquid, but mucosa of colon segment seen well. D, segment score 3: entire mucosa of colon segment seen well with no residual staining, small fragments of stool and/or opaque liquid

Figure 1

The Boston Bowel Preparation Scale (BBPS). A, segment score 0: unprepared colon segment with mucosa not seen due to solid stool that cannot be cleared. B, segment score 1: portion of mucosa of the colon segment seen, but other areas of the colon segment not well seen due to staining, residual stool and/or opaque liquid. C, segment score 2: minor amount of residual staining, small fragments of stool and/or opaque liquid, but mucosa of colon segment seen well. D, segment score 3: entire mucosa of colon segment seen well with no residual staining, small fragments of stool and/or opaque liquid

Figure 2

Distribution of Boston Bowel Preparation Scale scores applied during 633 screening colonoscopies. The distribution approximates a bell-shaped curve with a median score of 6 and an interquartile range of 6-7.

Figure 3

We determined the mean (SD) Boston Bowel Preparation Scale score (y-axis) assigned for each categorical bowel preparation rating (x-axis) observed during 633 screening colonoscopies. The decreasing trend in scores across decreasing categorical preparation qualities was statistically significant (p