Table 5. Risk of bias assessment using the Newcastle-Ottawa Scale. A maximum of 4 stars can be given in the Selection and Outcome/exposure domains and a maximum 2 stars can be given in the Comparability domain .

	Newcastle Ottawa scale for risk of bias assessment				GRADE assessment
	Selection	Comparability	Outcome/exposure	Overall quality assessment	Certainty of evidence
Gorenstein[30]	⋆⋆⋆⋆	⋆⋆	⋆⋆⋆	Good	Moderate