Comparison 7. Subgroup analyses ‐ Methodological criteria.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Single versus multi‐centre trials	14	1895	Mean Difference (IV, Random, 95% CI)	‐5.62 [‐8.95, ‐2.29]
1.1 Single centre trials	6	302	Mean Difference (IV, Random, 95% CI)	‐2.20 [‐7.95, 3.55]
1.2 Multi‐centre trials	8	1593	Mean Difference (IV, Random, 95% CI)	‐6.49 [‐10.75, ‐2.22]
2 Single versus multi‐centre trials	13		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
2.1 Single centre trials	6	188	Risk Ratio (M‐H, Random, 95% CI)	1.77 [1.20, 2.60]
2.2 Multi‐centre trials	7	1084	Risk Ratio (M‐H, Random, 95% CI)	1.44 [1.20, 1.72]
3 Industry versus non‐industry funded trials	13	1899	Mean Difference (IV, Random, 95% CI)	‐6.49 [‐9.64, ‐3.34]
3.1 Industry funded trials	12	1840	Mean Difference (IV, Random, 95% CI)	‐6.83 [‐10.09, ‐3.57]
3.2 Non‐industry funded trials	1	59	Mean Difference (IV, Random, 95% CI)	‐0.90 [‐12.31, 10.51]
4 Industry versus non‐industry funded trials	12		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
4.1 Industry funded trials	9	1053	Risk Ratio (M‐H, Random, 95% CI)	1.61 [1.41, 1.84]
4.2 Non‐industry funded trials	3	105	Risk Ratio (M‐H, Random, 95% CI)	1.53 [0.81, 2.87]