Comparing trans-oral endoscopic thyroidectomy vestibular approach and trans-areolar approaches regarding postoperative infections and swallowing difficulty

Table 4 The risk of bias of the included studies (Newcastle Ottawa Scale)

Ref.	Selection	Compatibility	Outcome	Score
Guo et al[14]	2	2	3	7
Shen et al[15]	2	2	3	7
Xu et al[9]	2	2	3	7
Yan et al[8]	2	2	3	7
Zhang et al[17]	2	1	3	6
Zhang et al[16]	2	2	3	7