Risk of bias of studies.
| Study | Adequate Sequence Generation | Allocation Concealment | Blinding | Incomplete Outcome Data Addressed | Free of Selective Reporting | Free of Other Bias |
|---|---|---|---|---|---|---|
| De Boer 200844 | Unclear | Unclear | Unclear | Unclear | Unclear | Yes |
| Kong 200745 | Yes | No | Unclear | Yes | Unclear | No |
| Lim 200846 | Yes | Yes | Yes | Yes | Unclear | No |
| Marco 200747 | Yes | Yes | Yes | Yes | Unclear | Yes |
| Yelnik 200748 | Yes | Unclear | Unclear | Yes | Unclear | No |
| Singh 200949 | Yes | Yes | Yes | Yes | Yes | No |
↵“Unclear”: enough information was not available to make a determination regarding that criterion.