Randomized, double-blinded, placebo-controlled trial evaluating simethicone pretreatment with bowel preparation during colonoscopy

Table 1 Inclusion and exclusion criteria

Inclusion	Exclusion
Male and female patients between 18-80 yr old	Patients under 18 or over 80 yr old
Outpatient, elective colonoscopies	Severe constipation
Patients using Gatorade-Polyethylene Glycol 3350-Bisacodyl bowel prep	Suspected bowel perforation or obstruction
	Uncontrolled hypertension
	Urgent/emergent colonoscopies
	History of bowel resection
	Allergy to simethicone

Table 2 Adverse events, n (%)

	Simethicone, n = 84	Placebo, n = 84
Abdominal pain/Cramping	10 (8)	12 (14)
Nausea	13 (15)	20 (24)
Vomiting	4 (5)	6 (7)
Serious adverse events
Rash	1 (1)	1 (1)
Itching	1 (1)	None

Table 3 Inter-observer variability

Intraluminal bubbles grade	Kappa value	P-value
1	0.5687	< 0.001
2	0.2605	< 0.001
3	0.3481	< 0.001
4	0.5440	< 0.001
Combined	0.4024	< 0.001

Kappa statistic is a measure of agreement scaled 0 to be when amount of agreement is what would be due to chance and 1 when there is perfect agreement. Intermediate values suggest the following interpretations. Below 0.0 Poor, 0.01-0.20 Slight, 0.21-0.40 Fair, 0.41-0.60 Moderate, 0.61-0.80 Substantial, 0.81-1.00 almost perfect.

Table 4 Demographics, Intraluminal Bubble Scale, and Boston Bowel Preparation Scale characteristics, n (%)

	Simethicone	Placebo	P-value
Baseline characteristics
Gender			0.436
Female	50 (59.5)	45 (53.6)
Male	34 (40.5)	39 (46.4)
mean age (yr ± SD)	59.6 ± 14.0	54.0 ± 16.4	0.019
Median age (yr)	63 (IQR; 51-70)	57 (IQR; 43-68)	0.033
Outcomes
Intraluminal Bubbles Scale			< 0.001
1	73 (86.9)	46 (54.8)
2	7 (8.3)	18 (21.4)
3	2 (2.4)	13 (15.5)
4	2 (2.4)	7 (8.3)
Boston Bowel Prep Scale			0.832
3	2 (2.4)	1 (1.2)
4	0 (0.0)	1 (1.2)
5	2 (2.4)	1 (1.2)
6	26 (31.0)	31 (36.9)
7	13 (15.5)	13 (15.5)
8	9 (10.7)	9 (10.7)
9	32 (38.1)	27 (32.1)
Missing	0 (0.0)	1 (1.2)

IQR: Inter quartile range. The P-value for median calculated using Wilcoxon rank-sum test.

Table 5 Preparation efficacy end points, n (%)

	Simethicone, n = 84	Placebo, n = 84	P-value
Intraluminal Bubbles Scale
mean (± SD)	1.20 ± 0.60	1.77 ± 1.00	< 0.001
Low grade (I+II)	80 (55.6)	64 (44.4)	0.184
High grade (III + IV)	4 (16.7)	20 (83.3)	0.007
Boston Bowel Preparation Score (BBPS)
mean (± SD)	7.42 ± 1.51	7.28 ± 1.44	0.542
Mean cecal insertion time (± SD)	6.06 ± 3.55	5.48 ± 2.82	0.252
Mean withdrawal time (± SD)	11.73 ± 5.52	11.23 ± 3.99	0.500
No polyps	37 (49.3)	38 (50.7)	0.907
Total polyps	127 (56.7)	97 (43.3)	0.047
Adenomas	86 (65.6)	45 (34.4)	0.001
Sessile serrated polyps	4 (3.2)	7 (7.2)	0.163
Large polyps (> 5 mm), (mean ± SD)	1.13 ± 1.71	1.16 ± 1.27	0.937
Small polyps (1 mm - 4 mm), (mean ± SD)	1.56 ± 1.92	1.00 ± 1.14	0.093
Right sided polyps (mean ± SD)	1.23 ± 1.95	0.98 ± 0.96	0.429
Left sided polyps	1.53 ± 1.56	1.18 ± 1.19	0.228

BBPS was calculated out of total of 9. Intraluminal Bubbles Scale was calculated out of total of 4. Grade 1 was equivocal to > 90% mucosa clear of bubbles with no necessity of irrigation; Grade 2 was 75%-89% mucosa clear of bubbles with no necessity of irrigation; Grade 3 was 50%-74% mucosa clear of bubbles and required irrigation; Grade 4 was < 50% mucosa clear of bubbles and required irrigation. Total Polyps include hyperplastic polyps, benign polypoid mucosa, hyperplastic polyps, tubular adenomas, tubulovillous adenomas, and sessile serrated polyps. SD: Standard deviation. Mean cecal insertion time and mean withdrawal time values are denoted in minutes.