Table 2.

Summary of parameters for the intervention and control groups for the key studies

Authors	Intervention group			Control group
	Mean	SD	N	Mean	SD	N
Zhou et al. 2006 [11]	109	11	153	109	11	149
Parsons et al. 2008 [20]	8.6	6.3	132	9.2	5.9	132
Li et al. 2009 [27]	102.44	4.475	438	102.65	4.42	471
Chang et al. 2013 [26]	100.2	15.7	466	98	15.3	384
Li et al. 2015 [28]	88.98	12.69	562	89.82	14.07	604
Christian et al. 2010 [12]	51.7	8.5	103	48.2	10.2	177
Angulo Barroso et al. 2016 [18]	87.5	0.95	298	87.4	0.95	288