Funding for this research was provided by:
Medical Research Council (MC_UU_12017/13)
Scottish Government Chief Scientist Office (SPHSU13)
Article History
Received: 11 May 2020
Accepted: 20 November 2020
First Online: 4 December 2020
Ethics approval and consent to participate
: We use secondary data and ethics approval was not required.
: Not applicable.
: The authors declare that they have no competing interests.