Comparison 1. Clonidine versus placebo or no treatment.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Number requiring additional analgesia at any time postoperatively	3		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.1 Any dose clonidine	3	250	Risk Ratio (M‐H, Random, 95% CI)	0.28 [0.05, 1.45]
1.2 Low dose clonidine	1	45	Risk Ratio (M‐H, Random, 95% CI)	1.0 [0.78, 1.28]
1.3 High dose clonidine	3	205	Risk Ratio (M‐H, Random, 95% CI)	0.24 [0.11, 0.51]
1.4 High dose clonidine, studies with lower risk of bias	2	160	Risk Ratio (M‐H, Random, 95% CI)	0.24 [0.09, 0.69]
2 Number pain‐free in PACU	2		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
2.1 Any dose clonidine	2	190	Risk Ratio (M‐H, Random, 95% CI)	11.50 [1.55, 85.29]
2.2 Low dose clonidine	1	45	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
2.3 High dose clonidine	2	145	Risk Ratio (M‐H, Random, 95% CI)	11.50 [1.57, 84.38]
3 Postoperative pain score	2		Std. Mean Difference (IV, Random, 95% CI)	Subtotals only
3.1 Low dose clonidine	1	45	Std. Mean Difference (IV, Random, 95% CI)	0.23 [‐0.40, 0.85]
3.2 High dose clonidine	2	145	Std. Mean Difference (IV, Random, 95% CI)	‐1.11 [‐1.46, ‐0.75]