Electrolyte changes after bowel preparation for colonoscopy: A randomized controlled multicenter trial

Table 1 Characteristics of all subjects and outcomes n (%)

	PEG-Asc	4-L PEG	P value
n	112	114
Age (yr, mean ± SD)	56 ± 10	55 ± 12	0.525
Sex (male)	54.50%	64%	0.143
Previous colonoscopy	55 (49.1)	58 (50.9)	0.790
Complete bowel preparation	112 (100)	111 (97.4)	0.247
Morning colonoscopy	68 (60.7)	54 (47.4)	0.044
Indications of colonoscopy			0.515
Colon cancer screening	65 (58)	71 (62.3)
Functional GI symptoms	47 (42)	43 (37.7)
Polyp detection rate
Polyp ≥ 1	58 (51.8)	53 (46.5)	0.506
Procedure time
Insertion time (min, mean ± SD)	5.8 ± 4.5	5.8 ± 3.3	0.938
Withdrawal time (min, mean ± SD)	9.4 ± 5.5	8.4 ± 2.4	0.420

PEG-Asc: Low-volume (2-L) polyethylene glycol solution + ascorbic acid 4.7 g; 4-L PEG: High-volume (4-L) polyethylene glycol solution; GI: Gastrointestinal.

Table 2 Laboratory findings before and after intake of the bowel preparation solutions

	PEG-Asc	4-L PEG	P value1
Serum
Sodium			0.161
Before, mmol/L	140.0 ± 2.4	139.8 ± 1.9
After, mmol/L	140.8 ± 2.6a	141.1 ± 2.1a
Potassium			0.005
Before, mmol/L	4.1 ± 0.3	4.2 ± 0.3
After, mmol/L	4.2 ± 0.4	4.0 ± 0.4a
Chloride			0.259
Before, mmol/L	103.4 ± 3.3	103.2 ± 2.8
After, mmol/L	105.3 ± 3.4a	103.2 ± 3.1
Magnesium			0.447
Before, mg/dL	2.2 ± 0.2	2.2 ± 0.1
After, mg/dL	2.1 ± 0.2	2.1 ± 0.2
Phosphorus			0.009
Before, mg/dL	3.4 ± 0.4	3.4 ± 0.5
After, mg/dL	3.6 ± 0.5a	3.4 ± 0.4
Calcium			0.174
Before, mg/dL	8.9 ± 0.5	8.9 ± 0.9
After, mg/dL	9.7 ± 8.1	9.0 ± 0.4
Urea			0.624
Before, mg/dL	14.0 ± 4.7	13.8 ± 3.4
After, mg/dL	13.1 ± 4.6a	12.6 ± 3.9a
Creatinine			0.172
Before, mg/dL	1.0 ± 1.1	0.8 ± 0.2
After, mg/dL	0.8 ± 0.2	0.8 ± 0.2
Serum osmolarity			0.733
Before, mmol/kg	293.1 ± 31.2	291.6 ± 8.2
After, mmol/kg	294.4 ± 57.8	291.1 ± 11.5
Urine
Urine osmolarity			0.741
Before, mmol/L	633.2 ± 222.1	639.7 ± 212.4
After, mmol/L	694.4 ± 216.1a	693.8 ± 183.7a

¹P values were calculated as interactions of preparation method and time by linear mixed model.

^aP < 0.05 vs baseline by paired t-test. Data given as mean ± SD. PEG-Asc: Low-volume (2-L) polyethylene glycol solution + ascorbic acid 4.7g; 4-L PEG: High-volume (4-L) polyethylene glycol solution.

Table 3 Proportion of patients with over-changed values n (%)

	PEG-Asc	4-L PEG	P value
	(n = 112)	(n = 114)
Na change > 4.5 mmol/L	7 (6.3)	14 (12.4)	0.113
K change > 0.8 mmol/L	5 (4.5)	6 (5.3)	0.769
Ca change > 0.7 mg/dL1	4 (3.6)	4 (3.5)	> 0.999
Mg change > 0.7 mg/dL1	2 (1.8)	0 (0)	0.244
P change > 0.7 mg/dL	21 (18.8)	16 (14.0)	0.338
S osm change > 7.5 mmol/kg	61 (54.5)	51 (44.7)	0.144
Cr change > 0.7 mg/dL	0 (0)	0 (0)	> 0.999

¹Fisher’s exact test. PEG-Asc: Low-volume (2-L) polyethylene glycol solution + ascorbic acid 4.7 g; 4-L PEG: High-volume (4-L) polyethylene glycol solution.

Table 4 Scores of adequacy of bowel preparation according to the Boston Bowel Preparation Scale

	PEG-Asc	4-L PEG	P value
Right segment	2.2 ± 0.8	2.3 ± 0.7	0.175
Transverse segment	2.4 ± 0.8	2.4 ± 0.7	0.687
Left segment	2.4 ± 0.8	2.5 ± 0.8	0.610
Total segment	7.0 ± 2.1	7.1 ± 2.0	0.601

PEG-Asc: Low-volume (2-L) polyethylene glycol solution + ascorbic acid 4.7 g; 4-L PEG: High-volume (4-L) polyethylene glycol solution.

Table 5 Adverse events and subjective feelings n (%)

	PEG-Asc	4-L PEG	P value
Adverse events
Nausea	32 (28.6)	34 (29.8)	0.836
Vomiting	7 (6.3)	12 (10.5)	0.247
Abdominal pain	11 (9.8)	10 (8.8)	0.786
Abdominal distension	38 (33.9)	45 (39.5)	0.387
Thirst	25 (22.3)	21 (18.4)	0.467
Dizziness	13 (11.6)	7 (6.1)	0.148
Aphtous ulcer	2 (1.8)	1 (0.9)	0.620
Subjective feelings
Feel difficult	16 (14.3)	35 (30.7)	0.003
Taste “good”	46 (41.1)	19 (16.7)	< 0.001
Willingness	82 (73.2)	67 (59.3)	0.027

PEG-Asc: Low-volume (2-L) polyethylene glycol solution + ascorbic acid 4.7 g; 4-L PEG: High-volume (4-L) polyethylene glycol solution.