Ethical Considerations
The ethical review was deemed unnecessary due to the nature of this
study (a systematic review). However, all data were confidentiality
observed and protected. All data used in this review were accessed and
evaluated only by the researchers and kept on personal
password-protected computers. The protocol for this systematic review
was registered in the International Prospective Register of Systematic
Reviews (PROSPERO) with a unique ID: CRD42021297129.