Table 4.

Assessment of risk of bias of Non-RCTS

Quality evaluation of the eligible studies with Newcastle–Ottawa scale
Study	Representativeness	Selection of non-exposed	Ascertainment of exposure	Outcome not present at the start	Comparability of most important factors	Comparability on other risk factors	Assessment of outcome	Long enough follow-up (median ≥ 1 year)	Adequacy (completeness of follow-up)
Abbas et al	✬	✬	✬	✬	✬	0	✬	0	✬
Adamina et al	✬	✬	✬	✬	✬	0	✬	0	✬
Christof et al	✬	✬	✬	✬	✬	✬	✬	✬	✬
Chung et al	✬	✬	✬	✬	✬	0	0	0	✬
Ellis et al	✬	✬	✬	✬	✬	0	0	0	✬
Fisher et al	✬	✬	✬	✬	✬	0	✬	0	✬
Wang et al	✬	✬	✬	0	✬	0	0	✬	✬
Abbas et al	✬	✬	✬	✬	✬	0	✬	0	✬