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

Table 4 Grades of Recommendation, Assessment, Development and Evaluation rated the certainty of evidence

No. of studies	Design	Risk of bias	Inconsistency	Indirectness	Imprecision	Other considerations	SSD	SpDs	RR (95%CI)	Effect/Absolute	Quality	Importance
Adequate bowel cleanliness
14	Randomized trials	No serious risk of bias	Serious1	No serious indirectness	No serious imprecision	None	2002/2468 (81.1%)	1973/2350 (84.0%)	RR 0.97 (0.92 to 1.02)	25 fewer per 1000 (from 67 fewer to 17 more)	(+++) moderate	Critical
								85.5%		26 fewer per 1000 (from 68 fewer to 17 more)
Right colon BBPS
9	Randomized trials	No serious risk of bias	No serious inconsistency	No serious indirectness	No serious imprecision	None	1869	1869	-	Md 0 higher (0.04 lower to 0.03 higher)	(++++) high	Critical
Right colon OBPS
5	Randomized trials	No serious risk of bias	Serious1	No serious indirectness	No serious imprecision	None	422	422	-	Md 0.04 higher (0.27 lower to 0.34 higher)	(+++) moderate	Critical
Sleep disturbance
15	Randomized trials	No serious risk of bias	Serious1	No serious indirectness	No serious imprecision	None	348/2591 (13.4%)	651/2463 (26.4%)	RR 0.52 (0.40 to 0.68)	127 fewer per 1000 (from 85 fewer to 159 fewer)	(+++) moderate	Critical
								32.0%		154 fewer per 1000 (from 102 fewer to 192 fewer)
Willingness to repeat
10	Randomized trials	No serious risk of bias	Serious1	No serious indirectness	No serious imprecision	None	1624/1996 (81.4%)	1269/1855 (68.4%)	RR 1.15 (1.03 to 1.29)	103 more per 1000 (from 21 more to 198 more)	(+++) moderate	Critical
								65.2%		98 more per 1000 (from 20 more to 189 more)
Nausea
17	Randomized trials	No serious risk of bias	Serious1	No serious indirectness	No serious imprecision	None	516/2715 (19.0%)	559/2592 (21.6%)	RR 0.95 (0.78 to 1.16)	11 fewer per 1000 (from 47 fewer to 35 more)	(+++) moderate	Critical
								20.0%		10 fewer per 1000 (from 44 fewer to 32 more)
Vomiting
16	Randomized trials	No serious risk of bias	Serious1	No serious indirectness	No serious imprecision	None	191/2644 (7.2%)	202/2521 (8.0%)	RR 0.96 (0.66 to 1.38)	3 fewer per 1000 (from 27 fewer to 30 more)	(+++) moderate	Critical
								7.2%		3 fewer per 1000 (from 24 fewer to 27 more)
Abdominal pain
17	Randomized trials	No serious risk of bias	Serious1	No serious indirectness	No serious imprecision	None	168/2715 (6.2%)	221/2592 (8.5%)	RR 0.75 (0.62 to 0.9)	21 fewer per 1000 (from 9 fewer to 32 fewer)	(+++) moderate	Critical
								8.2%		20 fewer per 1000 (from 8 fewer to 31 fewer)
Bloating
15	Randomized trials	No serious risk of bias	Serious1	No serious indirectness	No serious imprecision	None	322/2205 (14.6%)	415/2077 (20.0%)	RR 0.8 (0.63 to 1.01)	40 fewer per 1000 (from 74 fewer to 2 more)	(+++) moderate	Critical
								18.4%		37 fewer per 1000 (from 68 fewer to 2 more)

¹Only a few different studies have shown conflicting results. SSD: Same-day single-dose; SpDs: Split-dose; CI: Confidence interval; RR: Relative risk; BBPS; Boston Bowel Preparation Scale; Md: Moderate; OBPS: Ottawa Bowel Preparation Scale.