Table 2.

Quality evaluation of study methodology included in the literature.

Study	Random allocation	Allocation concealment	Blind method	Whether to describe loss of follow-up	Selective results report	Other migration	Quality grade
Leite et al. [24]	Unclear	High	High	Yes	Low	Low	B
Koutsioumpa et al. [13]	Low	High	High	Yes	Low	Low	B
Patsaki et al. [25]	Low	Low	Low	Yes	Low	Low	A
Acqua et al. [26]	Low	Low	Low	Yes	Low	Low	A
Kho et al. [27]	Unclear	Low	Low	Yes	Low	Low	B
Vivodtzev et al. [28]	Unclear	High	Low	Yes	Low	Low	B
Rodriguez et al. [29]	High	Low	Low	Yes	Low	Low	B
Meesen et al. [30]	High	High	Low	Yes	Low	Low	B
Gruther et al. [31]	Low	High	Low	Yes	Low	Low	B
Hong Chen et al. [32]	Low	High	High	No	Low	Low	B
Jianlan Sun et al. [33]	Low	High	High	No	Low	Low	B

Note: high: high risk offset; low: low risk offset. Yes: Loss of follow-up is described; No: There is no lost to follow-up.