Funding for this research was provided by:
NIHR School for Primary Care Research (390)
Received: 7 October 2019
Accepted: 4 February 2020
First Online: 13 March 2020
Ethics approval and consent to participate
: Not applicable as this is a synthesis of existing literature.
: Not applicable as this is drawing on previously published data that we appropriately reference in the paper.
: The authors declare that they have no competing interests.