Financial & competing interests disclosure
Charlotte Warren-Gash holds a MRC Clinical Research Training Fellowship. Liam Smeeth is supported by a Wellcome Trust Senior Research Fellowship in Clinical Science. Andrew Hayward is supported by the Camden Primary Care Trust. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
No writing assistance was utilized in the production of this manuscript.