16. Opioids versus placebo: risk ratio and number needed to treat for an additional harmful outcome (NNTH) for generic adverse events.

Adverse event	Studies	Participants	Statistical method	Risk ratio	NNTH
Any adverse event	6	5004	Risk Ratio (M‐H, Random, 95% CI)	1.42 (1.22, 1.66)	4.20 (3.78, 4.74)
Any serious adverse event	6	4324	Risk Ratio (M‐H, Fixed, 95% CI)	2.75 (2.06, 3.67)	28.71 (20.50, 47.88)
Withdrawals due to adverse events	10	11,510	Risk Ratio (M‐H, Fixed, 95% CI)	3.40 (3.02, 3.82)	5.55 (5.19, 5.97)

CI: confidence interval
 M‐H: Mantel‐Haenszel method of meta‐analysis