Comparison 7. Effect modification subgroup analysis: type of placebo interventions.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Psychological placebos	9	298	Risk Ratio (M‐H, Random, 95% CI)	0.88 [0.75, 1.04]
2 Physical placebos	11	2536	Risk Ratio (M‐H, Random, 95% CI)	0.91 [0.81, 1.01]
3 Pharmacological placebos	24	3207	Risk Ratio (M‐H, Random, 95% CI)	0.97 [0.89, 1.05]
4 Psychological placebos	53	2546	Std. Mean Difference (IV, Random, 95% CI)	‐0.22 [‐0.31, ‐0.12]
5 Physical placebos	61	3922	Std. Mean Difference (IV, Random, 95% CI)	‐0.31 [‐0.41, ‐0.22]
6 Pharmacological placebos	44	4045	Std. Mean Difference (IV, Random, 95% CI)	‐0.10 [‐0.20, ‐0.01]