Table 1.

Characteristics of selected studies.

Author	Study Type	Region	No. Of Patients	Demographics	Definition of Adequate Bowel Preparation	Diet During Bowel Preparation Phase	Type Bowel Preparation Solution
Park et al 2009	RCT	South Korea	214	Male: 120 (56.1%) Female: 94 (43.9%) Mean Age: 53.1–55.2 yr	Ottawa Scale No reported cut off for adequate preparation	Prepackaged low- residue diet all day vs Clear liquid diet all day	4L PEG with electrolytes on day of colonoscopy
Rapier et al 2006	RCT	USA	75	Male: 44 (58.7%) Female: 31 (41.3%) Mean Age: 61.0 yr	Aronchick Scale Adequate bowel preparation was excellent or good	Prepackaged low- residue diet all day vs Clear liquid diet all day	Magnesium citrate and bisacodyl (oral and rectal)
Scott et al 2004	RCT	USA	185	Male: 82 (44.3%) Female: 103 (55.7%) Mean Age: 56.9–57.0 yr	Aronchick Scale Adequate bowel preparation was excellent or good	Regular breakfast then low-residue diet lunch, then clear liquids rest of day vs Light breakfast then clear liquid rest of day	Sodium phosphates oral solutions split-dose
Sipe et al 2013	RCT	USA	196	Male: 93 (47.4%) Female: 103 (52.6%) Mean Age: 56.9–57.8 yr	Boston Bowel Preparation Scale No reported cut off for adequate preparation	Low-residue diet for breakfast, lunch, snack, then clear liquids rest of day vs Clear liquid diet all day	Oral sulfate solution split-dose
Soweid et al 2010	RCT	Lebanon	200	Male: 105 (52.5%) Female: 95 (47.5%) Mean Age: 55.5–56.6 yr	Aronchick Scale Adequate bowel preparation was excellent or good	Low-residue diet for breakfast, lunch, dinner vs Clear liquid diet all day	4L PEG with electrolytes the evening prior
Melicharkova et al 2013	RCT	Canada	213	Male: 109 (51.2%) Female: 104 (48.8%) Mean Age: 56.5–57.1 yr	Ottawa and Aronchick Scales Adequate bowel preparation were excellent or good	Low-residue diet for breakfast, then clear liquids the rest of day vs Clear liquid diet all day	Sodium picosulfate + magnesium citrate + bisacodyl evening prior for morning procedures and day of for afternoon procedures
Stolpman et al 2014	RCT	USA	201	Male: 114 (56.7%) Female: 87 (43.3%) Mean Age: 60 yr	Boston Bowel Preparation Scale Adequate bowel preparation was score ≥ 6	Low-residue diet for breakfast and lunch, then clear liquids rest of day vs Clear liquid diet all day	Oral sulfate solution split-dose
Butt et al 2016	RCT	Australia	226	Male: 117 (51.8%) Female: 109 (48.2%) Mean Age: 52 yr	Harefield Cleansing Scale Adequate bowel preparation was score of A or B	Low-residue diet all day (white diet) vs Clear liquid diet all day	2L PEG + ascorbic acid evening prior for morning procedures and split-dose for afternoon procedures
Walter et al 2017	RCT	USA	140	Male: 60 (42.9%) Female: 80 (57.1%) Mean Age: NA	Boston Bowel Preparation Scale Adequate bowel preparation was score ≥ 6	Low-residue diet for breakfast and lunch, then clear liquids rest of day vs Clear liquid diet all day	2L PEG + ascorbic acid split-dose
Delegge et al 2005	RCT	USA	506	Male: 184 (36.4%) Female: 322 (63.6%) Mean Age: 54.3 yr	Custom standard, Adequate bowel preparation was excellent or good	Prepackaged low-residue diet all day vs Clear liquid diet all day	sodium phosphates (2 × 45-mL, split dose.) vs low volume dose of magnesium citrate and bisacodyl
Flemming et al 2015	RCT	Canada	214	Male: 86 (40.2%) Female: 128 (63.6%) Mean Age: 62–65 yr	Ottawa scale; Aronchick scale, Adequate bowel preparation was excellent or good	Low-residue diet for breakfast, then clear liquids rest of day vs Clear liquid diet all day	4L PEG-ELS solution, split-dosing or traditional dosing depend on colonoscopy time
Dwyer et al 2017	RCT	Australia	250	Male: 135 (54%) Female: 115 (46%) Mean Age: 54–54.5 yr	Ottawa scale, Adequate bowel preparation was score ≤ 6	White Diet vs Light breakfast, then clear fluids only	1L PEG or split-dose Picosalax + SPMC
Thukral et al 2017	RCT	USA	215	Male: 112 (52.3%) Female: 103 (47.7%) Mean Age: 55.8–57 yr	Boston Scale, Adequate bowel preparation was score > 5	Specific instructions on acceptable foods for breakfast, lunch, and evening snacks vs Clear liquid diet all day	Split dose magnesium citrate
Tikfu et al 2018	RCT	Malaysia	97	Male: 51 (53%) Female: 46 (47%) Age: 16–73 years old	The modified Aronchick bowel preparation quality scale.	Low-residue, lactose-free semi-elemental enteral formula vs Clear liquid diet	Sodium phosphate (PEG, 3 L in total instead if contraindicated)
Marco et al 2019	RCT	Spain	276	Male: 144 (52%) Female: 132 (48%) Mean Age: 59.9 yr	Boston bowel preparation scale	Low-fiber diet vs Clear liquid diet	4 L of polyethylene glycol in a split-dose regimen
Elisa et al 2019	RCT	Mexico	205	Male: 72 (35.1%) Female: 133 (64.9%) Mean Age: 55.6 yr	Boston bowel preparation scale	Low-residue diet vs Clear liquid diet	4-L preparation of single-dose PEG

RCT = randomized controlled trials.