Comparison 18. Risk of bias subgroup analysis: clearly concealed allocation + trial size >49 + dropout max 15%.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Binary outcomes	5	1438	Risk Ratio (M‐H, Random, 95% CI)	0.90 [0.76, 1.08]
1.1 Pain (incidence)	3	1109	Risk Ratio (M‐H, Random, 95% CI)	0.89 [0.67, 1.19]
1.2 Schizophrenia (lack of 50% improvement)	1	54	Risk Ratio (M‐H, Random, 95% CI)	0.95 [0.77, 1.17]
1.3 Nausea	1	275	Risk Ratio (M‐H, Random, 95% CI)	0.92 [0.75, 1.12]
2 Continuous outcomes	11	1610	Std. Mean Difference (IV, Random, 95% CI)	‐0.38 [‐0.55, ‐0.22]
2.1 Pain (various scales, see table of included studies for details)	7	1181	Std. Mean Difference (IV, Random, 95% CI)	‐0.45 [‐0.69, ‐0.21]
2.2 Nausea (Rhodes inventory of nausea and vomiting, escape medication)	2	174	Std. Mean Difference (IV, Random, 95% CI)	‐0.19 [‐0.49, 0.11]
2.3 Irritable bowel syndrome (Global improvement scale)	1	175	Std. Mean Difference (IV, Random, 95% CI)	‐0.41 [‐0.71, ‐0.11]
2.4 Depression (Beck depression inventory)	1	80	Std. Mean Difference (IV, Random, 95% CI)	‐0.23 [‐0.67, 0.21]
3 Pain heterogeneity	7	1181	Std. Mean Difference (IV, Random, 95% CI)	‐0.45 [‐0.69, ‐0.21]
3.1 GAT	4	544	Std. Mean Difference (IV, Random, 95% CI)	‐0.68 [‐0.85, ‐0.50]
3.2 Not GAT	3	637	Std. Mean Difference (IV, Random, 95% CI)	‐0.13 [‐0.28, 0.03]