Funding for this research was provided by:
Medical Research Council Canada (MR/K023187/1)
Text and Data Mining valid from 2019-09-06
Received: 5 June 2019
Accepted: 27 August 2019
First Online: 6 September 2019
Ethics approval and consent to participate
: Ethics approval for NDNS was obtained from the Oxfordshire Research Ethics Committee. No further ethical approval was required for the secondary analysis of anonymised data which is presented here.
: Not applicable.
: The authors declare that they have no competing interests.