Table 2. Subgroup analyses of prophylactic macrolide treatment on the prevention of acute exacerbations of COPD.

Variables (macrolide)	Number of patients with exacerbations			Rate of exacerbations per patient per year
	Studies (patients), No.	RR (95% CI)	P	Studies (patients), No.	RR (95% CI)	P
Clarithromycin 3 months	1 (67)	2.90 (0.61–13.93)	0.18	1 (67)	3.27 (0.53–20.18)	0.20
Azithromycin 3 months	1 (84)	0.46 (0.18–1.18)	0.11	1 (30)	0.38 (0.14–1.05)	0.06
Azithromycin 6–12 months	2 (1209)	0.82 (0.76–0.90)	0.00	3 (1231)	0.59 (0.37–0.93)	0.02
Erythromycin 6–12 months	3 (254)	0.49 (0.26–0.91)	0.02	3 (254)	0.53 (0.43–0.83)	0.01

RR, risk ratio