Table 3.

Quality assessment scores for the studies included in this meta-analysis.

First Author (year)	Selection	Comparability	Exposure	Total Points
Butali, 2011 [28]	***	*	***	7
Pan, 2011 [13]	***	**	***	8
Fontoura, 2012 [23]	**	*	**	5
Huang, 2012 [20]	****	*	***	8
Ludwig, 2014 [26]	****	-	***	7
Mi, 2014 [21]	***	**	***	8
Babu Gurramkond, 2015 [24]	***	**	***	8
do Rego Borges, 2015 [27]	****	-	***	7
Reiter, 2015 [25]	***	*	***	7
Sun, 2015 [22]	****	*	***	8

Each asterisk means one point.