Table 1.

Criteria for evaluating the methodological quality of the research studies[17].

Criterion	Assessment
Random sequence generation	+/–/?
Allocation concealment	+/–/?
Blinding of the research	+/–/?
Blinding of the participants	+/–/?
Blinding of the outcome assessment	+/–/?
Selective reporting	+/–/?
Incomplete outcome data	+/–/?
Other potential threats	+/–/?

+ = low risk, – = high risk, ? = unspecified risk.