Comparison 15. Safety: asthma.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
15.1 Cohort study (rate ratio)	3		Rate Ratio (IV, Random, 95% CI)	Subtotals only
15.1.1 All ages	3		Rate Ratio (IV, Random, 95% CI)	1.05 [0.80, 1.39]
15.2 Cohort study (risk ratio)	2		Risk Ratio (IV, Random, 95% CI)	Subtotals only
15.2.1 All ages	1		Risk Ratio (IV, Random, 95% CI)	1.33 [0.98, 1.80]
15.2.2 Age ≤ 6 years	1		Risk Ratio (IV, Random, 95% CI)	0.44 [0.19, 1.00]
15.2.3 Age between 11 and 16 years	1		Risk Ratio (IV, Random, 95% CI)	0.35 [0.16, 0.79]