Table 2.

Overall scientific quality of the cohort studies based on the Newcastle–Ottawa Scale (NOS).

Study Criterion	Yamada et al. (2006) [37]	Park et al. (2011) [38]	Delabre et al. (2015) [39]
Selection (maximum ****)	****	***	****
Comparability (maximum **)	**	*	*
Outcome (maximum ***)	***	**	***

Note: The symbol * indicates the number corresponding item applies to the study.