Evidence to suggest adoption of water exchange deserves broader consideration: Its pain alleviating impact occurs in 90% of investigators

Table 1 Water-aided colonoscopy and insufflation colonoscopy: Baseline characteristics and indications of 1091 patients

	WE (n = 371)	WI (n = 338)	AICD (n = 382)	P value1
Age, yr, mean (± SD)	59 (12.2)	59 (11.6)	59 (12.0)	0.627
Females, n (%)	149 (40.2)	140 (41.4)	151 (39.5)	0.873
Males, n (%)	222 (59.8)	198 (58.6)	231 (60.5)
BMI, mean (± SD)	26.7 (4.8)	26.5 (4.7)	26.4 (4.7)	0.607
Previous abdominal surgery, n (%)	141 (38.0)	116 (34.3)	116 (30.4)	0.087
Indications for colonoscopy, n (%)
Abdominal pain	68 (18.3)	52 (15.4)	59 (15.4)	0.127
Bleeding	90 (24.3)	89 (26.3)	108 (28.3)	0.076
Change in bowel habits	73 (19.7)	64 (18.9)	60 (15.7)	0.977
Anemia	8 (2.2)	12 (3.6)	7 (1.8)	0.048
Diverticulosis	4 (1.1)	5 (1.5)	7 (1.8)	0.787
Other	46 (12.4)	37 (10.9)	46 (12.0)	0.403
Screening	82 (22.1)	79 (23.4)	95 (24.9)	0.361

¹ANOVA. n: Number of patients; WE: Water exchange for insertion, insufflation with air or CO₂ for withdrawal; WI: Water immersion for insertion, insufflation with air or CO₂ for withdrawal; AICD: Insufflation with air or CO₂ for insertion and withdrawal; SD: Standard deviation.

Table 2 Variations among investigators

	Real-time maximum insertion pain, mean (95%CI)			P value
	WE (n =371)	WI (n = 338)	AICD (n = 382)
All investigators	2.8	3.8	4.4	< 0.00051
	(2.6-3.0)	(3.5-4.1)	(4.1-4.7)	WE vs WI < 0.00052
				WE vs AICD < 0.00052
				WI vs AICD 0.0022
Investigator	WE	WI	AICD	Females (%)	BMI (± SD)	Previous abdominal surgery (%)	Abdominal compression (%)	Loop reduction (%)	Insertion time, min (±SD)
1	2.1	4.0	4.7	46.3	26.1 (4.9)	51.3	57.5	61.3	13 (6.5)
	(1.7-2.5)	(3.4-4.7)	(4.1-5.3)
2	2.9	3.3	4.1	32.9	27.0 (4.8)	46.8	67.1	63.3	11 (5.5)
	(2.4-3.3)	(2.8-3.9)	(3.5-4.7)
3	2.3	2.3	4	28.6	27.5 (4.4)	7.1	57.1	7.1	11 (4.4)
	(1.0-3.6)	(1.0-3.6)	(2.9-5.2)
4	2.4	1.9	2.8	28.6	25.6 (4.2)	10.7	71.4	21.4	15 (6.7)
	(1.7-3.2)	(0.6-3.3)	(2.0-3.5)
5	2.9	3.7	3.5	46.2	24.6 (3.3)	7.7	92.3	84.6	9 (2.8)
	(1.8-4.0)	(2.3-5.1)	(2.2-4.8)
6	2.4	2.6	3.5	60.9	28.4 (6.8)	13.0	73.9	52.2	10 (4.0)
	(1.6-3.3)	(1.5-3.7)	(2.5-4.5)
7	2.4	3.7	4.3	17.6	26.4 (2.5)	41.2	64.7	82.4	12 (7.2)
	(1.6-3.2)	(2.3-5.1)	(3.0-5.6)
8	2.8	2.4	2.4	50.0	25.6 (4.0)	35.7	92.9	92.9	15 (5.2)
	(2.0-3.6)	(1.7-3.0)	(1.4-3.3)
9	2.9	4.1	6.0	37.7	28.4 (5.2)	45.9	36.1	34.4	9 (3.1)
	(2.3-3.5)	(3.4-4.9)	(5.3-6.7)
10	5.3	7.1	7.0	50	27.2 (5.6)	35.7	21.4	10.7	8 (3.0)
	(4.4-6.2)	(6.3-8.0)	(6.2-7.9)
P values	< 0.00051	< 0.00051	< 0.00051	0.0741	0.0251	< 0.00051	< 0.00051	< 0.00051	< 0.00051

¹ANOVA;

²χ². n: Number of patients; WE: Water exchange for insertion, insufflation with air or CO₂ for withdrawal; WI: Water immersion for insertion, insufflation with air or CO₂ for withdrawal; AICD: Insufflation with air or CO₂ for insertion and withdrawal; SD: Standard deviation; BMI: Body mass index.

Table 3 Water exchange for insertion group, significant factors associated with increased pain score of Investigator number 8 vs all the other investigators, n (%)

	Investigator number 8 (n = 28)	All other investigators (n = 343)	P value
Abdominal pain as indication, females and males	11 (39.3)	57 (16.6)	0.0031
Females with abdominal pain as indication	9 (32.1)	21 (6.1)	< 0.00051
Females with previous abdominal surgery, any indication for colonoscopy	6 (21.4)	24 (7.0)	0.0181

¹χ².

Table 4 Investigator number 8, significant differences associated with increase in real-time maximum insertion pain score among methods, n (%)

	WE (n = 28)	WI (n = 28)	AICD (n = 24)	P value
Females and males, abdominal pain as indication	11 (39.3)	2 (7.1)	7 (29.2)	0.0171
				WE vs WI 0.0042
				WE vs AICD 0.4462
				WI vs AICD 0.0642
Females with abdominal pain as indication	9 (32.1)	1 (3.6)	3 (12.5)	0.0081
				WE vs WI 0.0052
				WE vs AICD 0.0592
				WI vs AICD 0.3522
Females with abdominal pain as indication and previous abdominal surgery	6 (21.4)	1 (3.6)	1 (4.2)	0.0311
				WE vs WI 0.0432
				WE vs AICD 0.0692
				WI vs AICD 0.9112

¹ANOVA;

²χ²; n: Number of patients; WE: Water exchange for insertion, insufflation with air or CO₂ for withdrawal; WI: Water immersion for insertion, insufflation with air or CO₂ for withdrawal; AICD: Insufflation with air or CO₂ for insertion and withdrawal; SD: Standard deviation; BMI: Body mass index.

Table 5 Pain during insertion, patients’ tolerance and sedation, n (%)

	WE (n = 371)	WI (n = 338)	AICD (n = 382)	P value
Painless unsedated colonoscopy2	50 (13.5)	26 (7.7)	23 (6.0)	WE vs WI 0.0131
				WE vs AICD < 0.00051
				WI vs AICD 0.3741
Unsedated, completed with only discomfort2	134 (36.1)	106 (31.4)	87 (22.8)	WE vs WI 0.1801
				WE vs AICD < 0.00051
				WI vs AICD 0.0091
Completed without sedation	321 (86.5)	287 (84.9)	292 (76.4)	WE vs WI 0.5371
				WE vs AICD < 0.00051
				WI vs AICD 0.0041
On-demand sedation	50 (13.5)	51 (15.1)	90 (23.6)	WE vs WI 0.5371
				WE vs AICD < 0.00051
				WI vs AICD 0.0041

¹χ²;

²Pain score based on numeric rating scale (NRS): 0 = absence of pain, 1-2 = discomfort, 10 = maximum pain. n: Number of patients; WE: Water exchange for insertion, insufflation with air or CO₂ for withdrawal; WI: Water immersion for insertion, insufflation with air or CO₂ for withdrawal; AICD: Insufflation with air or CO₂ for insertion and withdrawal; SD: Standard deviation.