Table 3.

The level of proof synthesis.

Location	Study type	Random sequence generation	Allocation concealment	Blinding of participants and researchers	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other bias	Eligibility for review	Overall level of proof
Wang T 2013	Controlled trial	√	√	√	√	√	√	?	Yes	High
Yang H 2024	Controlled trial	√	√	√	?	√	√	√	Yes	High
Yang X 2016	Controlled trial	√	?	?	?	√	√	√	Yes	Intermediate
Li P 2015	Controlled trial	√	√	√	?	√	√	√	Yes	High

x, high risk of bias; ?, insufficient information; √, low risk of bias.