Table 1.

Risk of bias of studies included in the review.

Author	Year	Risk level
Amona et al.	2020	Unclear
Anand et al.	2011	Unclear
Argy et al.	2018	High
Attia et al.	2015	Low
Awad et al.	2020	Unclear
Azoulay et al.	2018	Low
Báez-Saldaña et al.	2015	Low
Barreto et al.	2016	Unclear
Basiaga et al.	2018	Low
Beardsley et al.	2015	Unclear
Chen et al.	2020	Low
Choi et al.	2018	Unclear
Coelho et al.	2014	Unclear
Coyle et al.	2012	High
Creemers-Schild et al.	2016	Low
de Boer et al.	2011	Low
Evernden et al.	2020	Low
Faini et al.	2015	Unclear
Figueiredo-Mello et al.	2017	Low
Gabardi et al.	2012	Unclear
Gaborit et al.	2019	Low
Garg et al.	2018	Low
Haeusler et al.	2013	Low
Inoue and Fushimi	2019	Unclear
Kim et al.	2014	Low
Kim et al.	2015	Unclear
Kim et al.	2016	Low
Kim et al.	2017	Low
Kim et al.	2019	Low
Kitazawa et al.	2019	Unclear
Lagrou et al.	2015	Unclear
Lee et al.	2013	Low
Lee et al.	2019	High
Lee et al.	2020	Low
Lee et al.	2021	Unclear
Li et al.	2017	Low
Li et al.	2020	Low
Liu et al.	2020	Low
Lopez-Sanchez et al.	2015	Low
Lum et al.	2020	Unclear
Maartens et al.	2018	Low
Macedo-Viñas and Denning	2018	Unclear
Matsumura et al.	2014	Unclear
Mundo et al.	2020	Unclear
Nam et al.	2020	Low
Neofytos et al.	2018	Low
Nunokawa et al.	2019	Low
Ohmura et al.	2019	Low
Özenci et al.	2019	Unclear
Panizo et al.	2020	Unclear
Park et al.	2020	Low
PERCH Study Group	2019	Low
Quinn et al.	2018	Low
Rego de Figueiredo et al.	2019	Unclear
Rekhtman et al.	2019	Unclear
Saeed et al.	2015	Unclear
Schmidt et al.	2018	Low
Schoffelen et al.	2013	Low
Shi et al.	2020	Low
Singh et al.	2015	Unclear
Singh et al.	2019	Low
Solodokin et al.	2019	Low
Tanaka et al.	2015	Unclear
Tufa and Denning	2019	Unclear
Wang et al.	2019	Low
Wei et al.	2018	Low
Yanagisawa et al.	2020	Low
Yu et al.	2017	Low
Yukawa et al.	2018	Low