Comparison 2.

Antibiotics vs placebo, 15 trials: by universal prophylaxis

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Type of antibiotic prophylaxis	15		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.1 Universal prophylaxis	1	769	Risk Ratio (M‐H, Random, 95% CI)	0.33 [0.15, 0.73]
1.2 Not universal prophylaxis	10	5168	Risk Ratio (M‐H, Random, 95% CI)	0.65 [0.49, 0.87]
1.3 Unclear if universal prophylaxis	4	1088	Risk Ratio (M‐H, Random, 95% CI)	0.49 [0.32, 0.75]