Table 2

Methodological quality evaluation.

Authors	Design	Representatives of Exposed Cohort	Selection of Nonexposed Cohort	Ascertainment of Exposure	Assesment of Outcome	Length Follow-Up
Hellinger S et al22	●	●	●	●●	●●	●
Tacconi L et al13	●	●	●	●●	●●
Kyung-Hoon K et al14		●		●
Hahn P et al23*	●	●●		●
Heo DH et al24		●		●	●●	●
Siu CK et al25		●●	●	●●	●	●
Oertel JM et al26	●	●	●	●●	●●
Bruder M et al27		●●	●	●●	●	●
Denis DR et al2		●●	●	●●	●
Birch BD et al28		●		●	●	●
Eshraghi Y et al7		●		●	●	●
Zhenbo Z et al29		●	●	●●	●●	●
Alimi M et al30		●●	●	●●	●●●	●
Sukkarieh HG et al31		●	●	●●	●●
Knafo S et al32		●		●	●
Komp M et al33	●	●●	●	●●	●●●
Ortiz O et al51		●		●	●
Cambron SC et al11		●●		●●		●
Ganau M et al3		●		●	●	●
Ha SW et al35		●	●	●●	●
James A et al36		●		●	●●
Amoretti N et al11		●●	●	●●	●●
Landi A et al37		●	●	●●	●
Schulz M et al16	●	●		●		●
El Shazly A et al38		●		●	●	●
Matsumoto M et al39	●	●		●	●	●
Xu R et al40		●●		●●
Allen TL et al10		●	●	●●	●●●
Martha JF et al9		●		●	●●	●
Terao T et al41		●		●	●	●
Weiner BK et al39		●		●	●●
Sehati N et al43		●		●●	●
Acharya R et al1		●		●	●
Metellus P et al44		●●		●	●	●
Deinsberger R et al15		●		●	●	●
Sandhu FA et al45		●		●●	●
Epstein NE et al46		●●		●	●●
Pirotte B et al47		●		●	●	●
Bureau NJ et al12		●		●	●
Salmon B et al48		●		●	●	●
Banning CS et al46		●		●	●	●
Trummer M et al49		●	●	●	●
Lyons MK et al50		●●		●	●	●

Design: One dot for prospective or randomized controlled trials. Representatives of exposed cohort: One dot for study reporting detailed inclusion criteria, two dots for studies reporting detailed inclusion and exclusion criteria. Selection of non-exposed cohort: One dot for each study reporting a control group. Ascertainment of exposure: One dot for the authors confirming the intraoperative presence of a JFC, two dots if the histological confirmation was reported and an accurate JFC description provided. Assesment of outcome: One dot for each different clinical score utilized by authors for measuring postoperative outcomes. Length of follow-up: One dot if the follow-up was more than 24 months.