Comparison 1. Antibiotics in clean and clean‐contaminated ear surgery.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Effect of antibiotics on postoperative infection within three weeks after surgery	6	1291	Odds Ratio (M‐H, Fixed, 95% CI)	0.73 [0.45, 1.20]
2 Effect of antibiotics on postoperative infection after six weeks	2	196	Odds Ratio (M‐H, Fixed, 95% CI)	0.78 [0.30, 2.07]
3 Effect of antibiotics on postoperative infection within three months after surgery	2	172	Odds Ratio (M‐H, Fixed, 95% CI)	1.0 [0.38, 2.66]
4 Effect of antibiotics on the status of the outer ear canal two months after surgery	2	126	Odds Ratio (M‐H, Fixed, 95% CI)	0.29 [0.08, 1.13]
5 Effect of antibiotics on graft failure rate within three weeks after surgery	2	2282	Odds Ratio (M‐H, Fixed, 95% CI)	0.71 [0.35, 1.45]
6 Effect of antibiotics on graft failure rate between six weeks and three months after surgery	6	599	Odds Ratio (M‐H, Fixed, 95% CI)	0.86 [0.53, 1.41]
7 Effect of antibiotics on graft failure within three months after surgery	7	2735	Odds Ratio (M‐H, Fixed, 95% CI)	0.84 [0.56, 1.26]
8 Effect of antibiotics on adverse drug effects	2	841	Odds Ratio (M‐H, Fixed, 95% CI)	0.73 [0.20, 2.64]