Protocol and sources
The study was developed and completed in compliance with the PRISMA guidelines.10 The following electronic databases were searched: PubMed, MEDLINE (via Ovid) and Embase (via Ovid). The databases were searched from date of first publication until January 2021. We used MeSH and free text terms in conjunction to increase sensitivity to potentially relevant studies. For details of the search performed, see Supporting Information Appendix S1. Endnote software (X8; Clarivate Analytics, Philadelphia, PA, USA) was used to export and organise the abstracts, and subsequently remove duplicate publications.