Study timeline
| Review stage | Element | Status |
| Review question | PEOS determined | Completed November 2020 |
| Register review | PROSPERO | Completed December 2020 |
| Search strategy | Literature search in electronic databases and reference lists | Ongoing |
| Study selection | Title, abstract and full-text review | Ongoing |
| Data extraction | Data extraction form | Ongoing |
| Risk of bias | See figure 1 | Ongoing |
| Certainty of evidence | GRADE | Planned |
| Analysis | Narrative/meta-analysis (sensitivity and sub-group analysis as appropriate) | Planned |
| Publication | Journals and conferences (international and national) | Planned |
GRADE, Grading of Recommendations Assessment, Development and Evaluation; PEOS, Population-Exposure-Outcome-Study; PROSPERO, Prospective Register of Systematic Reviews.