Iron and ferritin effects on intensive care unit mortality: A meta-analysis

Table 2 Stratified analysis of iron parameters and mortality in critically ill patients according to study characteristics

Group	Number of the study	RR (95%CI)	P value	I2 (%)
Ferritin
Geographic region
Europe	6	1.001 (1.001-1.002)	< 0.01	94.3
America	5	1.002 (1.002-1.004)	0.293	19.1
Others	5	1.001 (1-1.001)	0.001	78.2
NOS
6	8	1.001 (1.001-1.001)	0.001	70.5
7	6	1.001 (1.001-1.001)	0.72	0
8	2	1.523 (1.383-1.663)	0.059	71.9
Patient types
Sepsis	7	1.001 (1.001-1.001)	0.004	68.2
Other critically ill patients	9	1.001 (1.001-1.002)	< 0.01	89.9
ICU types
Adult ICU	8	1.001 (1-1.001)	0	91.3
Pediatric ICU	5	1.001 (1.001-1.002)	0.017	66.9
General ICU	3	1.025 (0.25-1.8)	0.302	6.2
Iron
Geographic region
Europe	2	1.017 (0.988-1.045)	< 0.01	94.7
America	3	0.858 (0.573-1.143)	0.09	58.4
Others	2	1.616 (1.318-1.914)	0.583	0
NOS
6	4	1.217 (1.011-1.424)	0.001	82.7
7	3	1.017 (0.989-1.045)	< 0.01	89.9
Patient types
Sepsis	2	1.567 (1.208-1.925)	0.442	0
Other critically ill patients	5	1.017 (0.989-1.045)	< 0.01	87.2
ICU types
Adult ICU	5	1.043 (1.013-1.073)	0.001	79.7
General ICU	2	0.859 (0.780-0.939)	0.084	66.6

RR: Relative risk; NOS: Newcastle-Ottawa scale; ICU: Intensive care unit; I²: I-squared statistic.