Table 1.

Quality assessment of observational studies.

Study	Publication year	NOS score
Traykov [25]	2021	7
Chikata [17]	2017	9
Wang [24]	2021	7
Xu [15]	2017	9
Bun [14]	2015	8
Martin [13]	2018	8
Narui [26]	2017	9
Hama [27]	2017	7