Table 2.

Results of subgroup analysis based on different standards

	K	N	RR [95% CI]	P	Study heterogeneity				P (between-group comparison)
					Chi2	df	I2 (%)	P
Duration of treatment									0.40
≤ 3 days	14	1027	0.58 [0.48, 0.69]	< 0.001	13.75	13	5	0.39
> 3 days	3	453	0.66 [0.47, 0.81]	< 0.001	2.33	3	0	0.51
Daily dose									0.14
Low (≤ 0.25 g/kg)	10	685	0.52 [0.42, 0.65]	< 0.001	5.12	9	0	0.82
High (> 0.25 g/kg)	5	606	0.68 [0.55, 0.85]	< 0.001	7.06	4	29	0.22
Total dose									0.03
Low (< 0.9 g/kg)	11	740	0.50 [0.40, 0.62]	< 0.001	7.39	10	0	0.69
High (≥ 0.9 g/kg)	5	551	0.70 [0.56, 0.87]	0.002	3.80	4	0	0.43
Type of control intervention									0.14
Placebo	14	1141	0.57 [0.48, 0.67]	< 0.001	11.26	13	0	0.59
Human albumin solution	5	389	0.74 [0.54, 1.01]	0.05	1.56	4	0	0.45
Follow-up duration									0.21
≤ 28 days	11	1135	0.64 [0.54, 0.76]	< 0.001	10.14	10	1	0.43
> 28 days	3	158	0.35 [0.17, 0.71]	0.004	3.42	2	42	0.18
ICU days	5	237	0.56 [0.40, 0.77]	< 0.001	1.87	4	0	0.76
Study design									0.27
Randomized controlled trial	15	978	0.65 [0.53, 0.78]	< 0.001	10.72	14	0	0.71
Cohort study	4	552	0.35 [0.25, 0.50]	< 0.001	4.80	3	37	0.19
Publication year									0.21
Old studies (before 2005)	10	485	0.52 [0.40, 0.68]	< 0.001	6.38	9	0	0.70
Recent studies (from 2005)	9	1045	0.64 [0.54, 0.76]	< 0.001	10.05	8	20	0.26

K number of studies, N number of participants, ICU intensive care unit, RR relative risk, CI confidence interval