Comparison 8. Effect modification subgroup analysis: patient information.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Binary outcomes: patients not informed that the trial involved placebo	7	1085	Risk Ratio (M‐H, Random, 95% CI)	0.96 [0.83, 1.12]
2 Binary outcomes: patients informed that the trial involved placebo (or not stated)	37	4956	Risk Ratio (M‐H, Random, 95% CI)	0.93 [0.87, 0.99]
3 Continuous outcomes: patients not informed that the trial involved placebo	23	1692	Std. Mean Difference (IV, Random, 95% CI)	‐0.39 [‐0.53, ‐0.26]
4 Continuous outcomes: patients informed that the trial involved placebo (or not stated)	135	8821	Std. Mean Difference (IV, Random, 95% CI)	‐0.19 [‐0.25, ‐0.13]