Table 2. Association between trial characteristics and treatment effect in 84 comparisons.

Potential effect modifier	Negative direction of effect	Small size	Moderate effect size	Large effect size
	OR<1.0	OR≥1.0 and OR≤1.2	OR>1.2 and OR≤1.5	OR>1.5
Implementation received by physician	12 (16%)	15 (19%)	21 (27%)	29 (38%)
Implementation received by nurse	4 (17%)	4 (17%)	6 (25%)	10 (42%)
Implementation received by other professionals	1 (4%)	6 (21%)	5 (18%)	16 (57%)
Primary prevention	2 (9%)	5 (24%)	4 (19%)	10 (48%)
Secondary prevention	11 (18%)	9 (15%)	17 (27%)	25 (40%)
Tertiary prevention	3 (14%)	7 (33%)	6 (29%)	5 (24%)
Design: c-RCT	10 (17%)	15 (25%)	14 (23%)	21 (35%)
Design: RCT	3 (12%)	2 (8%)	8 (33%)	11 (46%)
Adherence as primary outcome	5 (12%)	7 (17%)	13 (32%)	16 (39%)
Adherence as secondary outcome	8 (19%)	10 (23%)	9 (21%)	16 (37%)
Follow-up <12 months	12 (18%)	12 (18%)	19 (29%)	23 (35%)
Follow-up ≥12 months	1 (6%)	5 (28%)	3 (17%)	9 (50%)

Abbreviations: RCT: randomized controlled trial; c-RCT: cluster randomized controlled trial; OR: odds ratio.