Footnotes

• Contributors MR and AB conceived the study, developed the search strategy, contributed to data collection, abstraction and interpretation. MR drafted the first manuscript. ADI and PC contributed to data collection, interpretation and provided critical revisions to the manuscript. All authors approved the final version of the manuscript.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests None declared.

• Provenance and peer review Not commissioned; internally peer reviewed.

• Patient consent for publication Not required.