Declarations
Competing interests: All authors have completed theunified competing interest form and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years, no other relationships or activities that could appear to have influenced the submitted work.
The lead author (the manuscript’s guarantor) affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted.
Ethical approval: not required
Details of funding: Not applicable
Statement of independence of researchers from funders: Not applicable
Patient involvement statement. Not applicable.
Data sharing statement: Not applicable.
