Funding for this research was provided by:
Health Service Executive, Republic of Ireland (HaPAI/2015/GM)
Public Health Agency Research and Development Office, Northern Ireland (STL/5187/15)
Received: 20 December 2018
Accepted: 25 April 2019
First Online: 14 May 2019
Ethics approval and consent to participate
: Ethical approval for NDNS RP was obtained from the Oxfordshire A Research Ethics Committee. All participants provided written informed consent [CitationRef removed, CitationRef removed].
: Not applicable.
: The authors declare that they have no competing interests.
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