Comparison 1. SIC versus OC ‐ high‐quality and low‐quality trials regarding generation of the allocation sequence.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Intra‐operative complications	7	571	Risk Difference (M‐H, Fixed, 95% CI)	0.0 [‐0.02, 0.02]
1.1 High‐quality trials	1	50	Risk Difference (M‐H, Fixed, 95% CI)	0.0 [‐0.07, 0.07]
1.2 Low‐quality trials	6	521	Risk Difference (M‐H, Fixed, 95% CI)	0.0 [‐0.02, 0.02]
2 Minor complications	7	571	Risk Difference (M‐H, Random, 95% CI)	0.01 [‐0.03, 0.05]
2.1 High‐quality trials	1	50	Risk Difference (M‐H, Random, 95% CI)	‐0.04 [‐0.21, 0.13]
2.2 Low‐quality trials	6	521	Risk Difference (M‐H, Random, 95% CI)	0.02 [‐0.04, 0.07]
3 Severe complications (without bile duct injuries)	7	571	Risk Difference (M‐H, Fixed, 95% CI)	‐0.01 [‐0.04, 0.02]
3.1 High‐quality trials	1	50	Risk Difference (M‐H, Fixed, 95% CI)	‐0.04 [‐0.14, 0.06]
3.2 Low‐quality trials	6	521	Risk Difference (M‐H, Fixed, 95% CI)	‐0.01 [‐0.04, 0.02]
4 Bile duct injuries	7	571	Risk Difference (M‐H, Fixed, 95% CI)	0.0 [‐0.02, 0.02]
4.1 High‐quality trials	1	50	Risk Difference (M‐H, Fixed, 95% CI)	0.0 [‐0.07, 0.07]
4.2 Low‐quality trials	6	521	Risk Difference (M‐H, Fixed, 95% CI)	0.0 [‐0.02, 0.02]
5 Total complications	7	571	Risk Difference (M‐H, Random, 95% CI)	0.00 [‐0.06, 0.07]
5.1 High‐quality trials	1	50	Risk Difference (M‐H, Random, 95% CI)	‐0.08 [‐0.26, 0.10]
5.2 Low‐quality trials	6	521	Risk Difference (M‐H, Random, 95% CI)	0.01 [‐0.06, 0.08]
6 Operative time (minutes)	3	210	Mean Difference (IV, Fixed, 95% CI)	1.94 [‐1.37, 5.25]
6.1 High‐quality trials	0	0	Mean Difference (IV, Fixed, 95% CI)	0.0 [0.0, 0.0]
6.2 Low‐quality trials	3	210	Mean Difference (IV, Fixed, 95% CI)	1.94 [‐1.37, 5.25]
7 Hospital stay (days)	2	180	Mean Difference (IV, Random, 95% CI)	‐2.78 [‐4.94, ‐0.62]
7.1 High‐quality trials	0	0	Mean Difference (IV, Random, 95% CI)	0.0 [0.0, 0.0]
7.2 Low‐quality trials	2	180	Mean Difference (IV, Random, 95% CI)	‐2.78 [‐4.94, ‐0.62]