Optimizing Adequacy of Bowel Cleansing for Colonoscopy
Optimizing Adequacy of Bowel Cleansing for Colonoscopy
Bowel Preparation Quality Scales
Bowel preparation quality has been described using a variety of approaches, typically categorizing the quality as excellent, good, fair, or poor. However, these terms lack standardized definitions. Automated processes for quantification of the quality of a bowel preparation are under development, but are not ready for clinical application For a bowel preparation scale to be of clinical value, it should be both valid and reliable Validity refers to measuring what is intended to be measured, as determined by experts. Reliability refers to the reproducibility, such as between different observers examining the same information
Numerous bowel preparation quality scales have been reported, but few have undergone a formal assessment of validity. The Aronchick scale (Table 1) describes the percentage of fluid or stool that covers the bowel surface and has κ intraclass correlation coefficients ranging from very good (0.79) for the cecum to poor (0.31) for the distal colon. Given that there are no reliability data and the scale downgrades quality for retained fluid, this scale is not recommended for clinical practice.
The Ottawa scale assesses cleanliness and fluid volume separately. Cleanliness for the right, mid-, and rectosigmoid segments are scored separately with scores of 0–4 for each segment. A summary score is reported for overall cleanliness (Figure 1). Additionally, the quantity of fluid is scored from 0 (perfect) to 2 (large) and this is added to the cleanliness value with a maximum total of 14 (solid stool throughout with lots of fluid). In the validation study, the Ottawa scale was found to have a significantly higher Pearson correlation coefficient than the Aronchick scale (0.89 vs 0.62; P <.001). Furthermore, the κ statistic and intraclass correlation coefficient was significantly higher (0.94 vs 0.77; P <0.001) Because the scale reports the quality of the preparation before washing and suctioning, the Ottawa scale is not recommended for clinical practice.
(Enlarge Image)
Figure 1.
Ottawa scale. The Ottawa bowel preparation quality scale use guide. (1) Part A of the scale is applied to each colon segment: right colon (Right), midcolon (Mid), and the rectosigmoid colon (Recto-Sigmoid). (2) The fluid quantity is a global value for the entire colon. (3) The score is calculated by adding the ratings of 0–4 for each colon segment and the fluid quantity rating of 0–2. (4) The scale has a range from 0 (perfect) to 14 (solid stool in each colon segment and lots of fluid; ie, a completely unprepared colon). (5) Before using the scale in a study or audit, observers need to perform a calibration exercise. Modified with permission from Gastrointest Endosc 2004;59:482–486.
The Boston Bowel Preparation Scale was developed specifically for application during withdrawal of the colonoscope, after all bowel cleansing has been completed The Boston Bowel Preparation Scale involves assigning each of 3 regions of the colon (right, transverse, and left) a score from 0 to 3 (Table 2). Each segment score is summed for a total Boston Bowel Preparation Scale score ranging from 0 to 9 (with 9 corresponding to a perfectly clean colon and 0 corresponding to a nonprepped colon). If the procedure is aborted because of an inadequate preparation, then the proximal segments are assigned a score of 0. A priori, the developers recommended that a score of less than 5 corresponds to an inadequate bowel preparation. The scale developers have published 4 endoscopic images depicting examples of preparations corresponding to scores of 0–3. Furthermore, a 15-minute training video was developed and is available on the Internet (https://www.cori.org/bbps/login.php). In the validation study, the weighted κ statistic for intra-observer agreement for the total Boston Bowel Preparation Scale score was 0.77, and the intraclass correlation coefficient for interobserver agreement was 0.74 Construct validity also was tested, comparing the Boston Bowel Preparation Scale score with a traditional scoring system (excellent, good, fair, poor, or unsatisfactory), the perception of inadequate bowel preparation, the polyp detection rate, and the insertion and withdrawal times from 633 screening colonoscopies. There was a significant decreasing trend in the mean Boston Bowel Preparation Scale score assigned to each category using the traditional system (P for trend <0.001). The polyp detection rate was 40%. For patients with a Boston Bowel Preparation Scale score of 5 or greater the polyp detection rate was 40%, compared with 24% for those with a score of less than 5 (P <0.02), and a repeat colonoscopy owing to inadequate preparation was recommended only 2% of the time, compared with 73% of the time for those with a score of less than 5 (P <0.001). Furthermore, the total Boston Bowel Preparation Scale scores were correlated inversely with both insertion and withdrawal times. In a follow-up validation study, the intraclass correlation coefficient was 0.91 and the intrarater reliability was substantial (weighted κ, 0.78). The Boston Bowel Preparation Scale was used prospectively by 12 attending gastroenterologists in 983 screening colonoscopies and showed an association between higher Boston Bowel Preparation Scale scores and polyp detection in the right and left colon, although no association was found for the transverse colon The Boston Bowel Preparation Scale has the best data for a validated scoring system.
Appendix B
Bowel Preparation Quality Scales
Bowel preparation quality has been described using a variety of approaches, typically categorizing the quality as excellent, good, fair, or poor. However, these terms lack standardized definitions. Automated processes for quantification of the quality of a bowel preparation are under development, but are not ready for clinical application For a bowel preparation scale to be of clinical value, it should be both valid and reliable Validity refers to measuring what is intended to be measured, as determined by experts. Reliability refers to the reproducibility, such as between different observers examining the same information
Numerous bowel preparation quality scales have been reported, but few have undergone a formal assessment of validity. The Aronchick scale (Table 1) describes the percentage of fluid or stool that covers the bowel surface and has κ intraclass correlation coefficients ranging from very good (0.79) for the cecum to poor (0.31) for the distal colon. Given that there are no reliability data and the scale downgrades quality for retained fluid, this scale is not recommended for clinical practice.
The Ottawa scale assesses cleanliness and fluid volume separately. Cleanliness for the right, mid-, and rectosigmoid segments are scored separately with scores of 0–4 for each segment. A summary score is reported for overall cleanliness (Figure 1). Additionally, the quantity of fluid is scored from 0 (perfect) to 2 (large) and this is added to the cleanliness value with a maximum total of 14 (solid stool throughout with lots of fluid). In the validation study, the Ottawa scale was found to have a significantly higher Pearson correlation coefficient than the Aronchick scale (0.89 vs 0.62; P <.001). Furthermore, the κ statistic and intraclass correlation coefficient was significantly higher (0.94 vs 0.77; P <0.001) Because the scale reports the quality of the preparation before washing and suctioning, the Ottawa scale is not recommended for clinical practice.
(Enlarge Image)
Figure 1.
Ottawa scale. The Ottawa bowel preparation quality scale use guide. (1) Part A of the scale is applied to each colon segment: right colon (Right), midcolon (Mid), and the rectosigmoid colon (Recto-Sigmoid). (2) The fluid quantity is a global value for the entire colon. (3) The score is calculated by adding the ratings of 0–4 for each colon segment and the fluid quantity rating of 0–2. (4) The scale has a range from 0 (perfect) to 14 (solid stool in each colon segment and lots of fluid; ie, a completely unprepared colon). (5) Before using the scale in a study or audit, observers need to perform a calibration exercise. Modified with permission from Gastrointest Endosc 2004;59:482–486.
The Boston Bowel Preparation Scale was developed specifically for application during withdrawal of the colonoscope, after all bowel cleansing has been completed The Boston Bowel Preparation Scale involves assigning each of 3 regions of the colon (right, transverse, and left) a score from 0 to 3 (Table 2). Each segment score is summed for a total Boston Bowel Preparation Scale score ranging from 0 to 9 (with 9 corresponding to a perfectly clean colon and 0 corresponding to a nonprepped colon). If the procedure is aborted because of an inadequate preparation, then the proximal segments are assigned a score of 0. A priori, the developers recommended that a score of less than 5 corresponds to an inadequate bowel preparation. The scale developers have published 4 endoscopic images depicting examples of preparations corresponding to scores of 0–3. Furthermore, a 15-minute training video was developed and is available on the Internet (https://www.cori.org/bbps/login.php). In the validation study, the weighted κ statistic for intra-observer agreement for the total Boston Bowel Preparation Scale score was 0.77, and the intraclass correlation coefficient for interobserver agreement was 0.74 Construct validity also was tested, comparing the Boston Bowel Preparation Scale score with a traditional scoring system (excellent, good, fair, poor, or unsatisfactory), the perception of inadequate bowel preparation, the polyp detection rate, and the insertion and withdrawal times from 633 screening colonoscopies. There was a significant decreasing trend in the mean Boston Bowel Preparation Scale score assigned to each category using the traditional system (P for trend <0.001). The polyp detection rate was 40%. For patients with a Boston Bowel Preparation Scale score of 5 or greater the polyp detection rate was 40%, compared with 24% for those with a score of less than 5 (P <0.02), and a repeat colonoscopy owing to inadequate preparation was recommended only 2% of the time, compared with 73% of the time for those with a score of less than 5 (P <0.001). Furthermore, the total Boston Bowel Preparation Scale scores were correlated inversely with both insertion and withdrawal times. In a follow-up validation study, the intraclass correlation coefficient was 0.91 and the intrarater reliability was substantial (weighted κ, 0.78). The Boston Bowel Preparation Scale was used prospectively by 12 attending gastroenterologists in 983 screening colonoscopies and showed an association between higher Boston Bowel Preparation Scale scores and polyp detection in the right and left colon, although no association was found for the transverse colon The Boston Bowel Preparation Scale has the best data for a validated scoring system.