Table 2. Quality assessment of included studies.

+: Symbol represents one score.

Author name	Selection	Comparability	Outcomes	Overall
Awan et al. [10]	+++	+	+++	Good
Dalen et al. [11]	+++	++	+++	Good
Dalen et al. [11]	+++	++	+++	Good
Hamad et al. [5]	++	++	+++	Good
Sun et al. [12]	+++	++	+++	Good
Sun et al. [12]	+++	++	+++	Good
Thuijs et al. [13]	+++	++	+++	Good