Same-day single-dose vs large-volume split-dose regimens of polyethylene glycol for bowel preparation: A systematic review and meta-analysis

Table 1 Characteristics of included studies

Ref.	Type of study	Participants and years of age	Bowel preparation	Patients with SSD/SpDs, n	Diet instruction	Colonoscopy timing	Outcomes	Interval, PC	Jadad score, modified	Use of adjuvant
Zhang et al[11], 2021	Single-center, single-blind, RCT	Outpatients 18-70 yr	SSD (A): 2 L PEG 6 h before procedure; SSD (B): 290 µg Lin 7 h before + 0.5 L water, 2 L PEG 6 h before colonoscopy; SpDs: 2 L PEG at 21:00 the day prior, 2 L PEG 6 h before colonoscopy	139A/141B/140	1-d LRD	Morning: 8:00-11:30; Afternoon: 13:30- 17:00	BBPS	6 h	4	SSD (B): Linaclotide
Barkun et al[12], 2020	Multicenter, single-blind, RCT	Outpatients ≥ 18 yr	SSD: 2 L PEG 4 h before colonoscopy + 15 mg bis at 14:00 the day before; SpDs: 2 L PEG at 19:00 the day before, 2 L PEG 4-5 h before colonoscopy	583/582	Not described	10:30-16:30	BBPS	2-3 h	5	Bisacodyl
Castro et al[13], 2019	Single-center, single-blind, RCT	Outpatients ≥ 18 yr	SSD: 4 L PEG at 6:00; SpDs: 2 L PEG at 18:00 the day before, 2 L PEG 6 h before colonoscopy	142/158	CLD after regular breakfast the day before	13:00-16:30	OBPS	Not described	5	No
Seo et al[14], 2019	Single-center, single-blind, RCT	Outpatients 40–75 yr	SSD (Mor): 4 L PEG at 5:00; SSD (Aft): 2 L PEG at 7:00 + 2 L PEG at 10:00; SpDs: 2 L PEG at 21:00 the day before, 2 L PEG at 7:00 (Mor) or at 10:00 (Aft)	172/167	LFF for 2 d, soft diet dinner the day prior	Morning 10:00-12:00; Afternoon 13:30-17:00	BBPS	Not described	3	No
Kang et al[15], 2018	Single-center, single-blind, RCT	Patients 18-70 yr	SSD: 2 L PEG 4-6 h before colonoscopy; SpDs: 2 L PEG at 19:00-21:00 the day before, 2 L PEG 4-6 h before colonoscopy	470/470	Regular meal for lunch and CLD or LRD for dinner the day before	Morning 8:30-12:00; Afternoon 13:00-16:00	BBPS	2-4 h	5	No
Zhang et al[16], 2015	Multicenter, single-blind, RCT	Patients 18-75 yr	SSD: 2 L PEG 4-6 h before colonoscopy; SpDs: 1 L PEG at 21:00 the day before, 2 L PEG 4-6 h before colonoscopy	159/159	1-d LRD	Not described	OBPS	2-4 h	3	No
Shah et al[17], 2014	Single-center, single-blind, RCT	Patients ≥ 18 yr	SSD: 2 L PEG at 5:00-7:00; SpDs: 1 L PEG at 18:00-19:00 the day before, 1 L PEG at 6:00-7:00	103/97	1-d liquid diet and CLD after midnight	11:00-16:00	OBPS	≥ 4 h	5	No
Tellez-Avila et al[18], 2014	Single-center, single-blind, RCT	Inpatients ≥ 18 yr	SSD: 2 L PEG at 6:00-8:00; SpDs: 2 L PEG at 17:00-19:00 the day before, 2 L PEG at 6:00-8:00	61/67	Not described	Not described	BBPS	≥ 3 h	5	No
Kotwal et al[19], 2014	Single-center, single-blind, RCT	Inpatients 18-80 yr	SSD: 4 L PEG at 5:00-9:00; SpDs: 2 L PEG at 19:00-21:00 the day before, 2 L PEG at 7:00-9:00	60/60	1-d CLD	After 11:00	OBPS	≥ 2 h	5	No
Kim et al[20], 2014	Single-center, single-blind, RCT	Outpatients 18-75 yr	SSD: 4 L PEG 6 h before colonoscopy; SpDs: 2 L PEG at 18:00 the day before, 2 L PEG 4-6 h before colonoscopy	50/50	Avoid high-fiber foods 3 d prior	Not described	OBPS	Not described	2	No
Seo et al[21], 2013	Single-center, single-blind, RCT	Outpatients 18-85 yr	SSD: 2 L PEG 5 h before colonoscopy; SpDs: 2 L PEG at 18:00 the day before, 2 L PEG 5 h before colonoscopy	103/102	3-d LRD	9:00-17:00	OBPS	≥ 3 h	5	No
Cesaro et al[22], 2013	Single-center, single-blind, RCT	Outpatients 18-85 yr	SSD: 2 L PEG-CS at 6:00 + bis 10-20 mg at 22:00 the day before; SpDs: 3 L PEG at 19:00 the day before, 1 L PEG at 7:00	50/51	3-d LRD	11:00-18:00	OBPS	Not described	5	Bisacodyl
Kwon et al[23], 2016	Multicenter, single-blind, RCT	Outpatients ≥ 18 yr	SSD: 1 L PEG-ASc + 0.5 L water at 6:00, 20 mg bis + 0.5 L water at 20:00 the day before; SpDs: 1 L PEG-ASc + 0.5 L water at 20:00 the day before, 1 L PEG-ASc + 0.5 L water at 6:00	92/97	LFF for 3 d, soft meal on the day prior	Not described	BBPS	≥ 3 h	5	Bisacodyl
Kang et al[24], 2017	Single-center, single-blind, RCT	Outpatients 20-75 yr	SSD: 1 L PEG-ASc 4 h before colonoscopy + 1 L water, 10 mg bis at 21:00 the day before; SpDs: 1 L PEG-ASc at 20:00 the day before + 0.5 L water, 1 L PEG-ASc 4 h before colonoscopy + 0.5 L water	100/100	3-d LRD	9:00-13:00	BBPS	> 2 h	3	Bisacodyl
Choi et al[25], 2018	Single-center, single-blind, RCT	Outpatient 18-80 yr	SSD: 1 L PEG-ASc 5 h before colonoscopy + 0.5 L water, Pru at 19:00 the day before + 0.5 L water; SpDs: 1 L PEG-ASc at 19:00 the day before + 0.5 L water, 1 L PEG-ASc 5 h before colonoscopy + 0.5 L water	130/130	3-d LRD	9:00-13:00	BBPS	Not described	5	Prucalopride
Kim et al[26], 2019	Single-center, single-blind, RCT	Outpatients 20-70 yr	SSD: 1L PEG-ASc at 5:00 + 1 L water + 20 mg bis; SpDs: 1 L PEG-ASc at 21:00 the day before + 0.5 L water, 1 L PEG-ASc at 5:00 + 0.5 L water	83/85	1-d CLD	8:30-12:00	BBPS	Not described	4	Bisacodyl
Kim et al[27], 2020	Single-center, single-blind, RCT	Patients 18-74 yr	SSD: 1 L PEG-ASc 5 h before endoscopy + 1 L water, 10 mg bis at 21:00 the day before; SpDs: 1 L PEG-ASc at 21:00 the day before + 0.5 L water, 1 L PEG-ASc 5 h before endoscopy + 0.5 L water	99/99	3-d LRD	9:00-17:00	BBPS	Not described	4	Bisacodyl
de Leone et al[28], 2013	Multicenter, single-blind, RCT	Outpatients 18-85 yr	SSD: 3-4 tablets bis at bedtime, 2 L PEG-CS 5 h before endoscopy; SpDs: 2 L PEG at 18:00 the day before, 2 L PEG 5 h before endoscopy	78/79	LFF for 3 d, CLD the day before	Morning	OBPS	Not described	4	Bisacodyl

SSD: Same-day single-dose; SpDs: Split-dose; PC: Preparation-to-colonoscopy; LFF: Low-fiber foods; LRD: Low residual diet; CLD: Clear liquid diet; PEG-CS: Polyethylene glycol with citrates and simethicone; PEG-ASc: Polyethylene glycol ascorbic acid; RCT: Randomized controlled trial; PEG: Polyethylene glycol; Lin: Linaclotide; BBPS: Boston Bowel Preparation Scale; bis: Bisacodyl; OBPS: Ottawa Bowel Preparation Scale; Mor: Morning; Aft: Afternoon; Pru: Prucalopride.