Funding for this research was provided by:
patient donations (patient donations)
Received: 13 September 2019
Revised: 31 December 2019
Accepted: 3 February 2020
First Online: 14 February 2020
Compliance with ethical standards
: The authors declare that they have no competing interests.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.The study was approved by NHS Research Ethics Committee (REC Reference Number 15/LO/0086). All participants gave informed consent before taking part.
: Informed consent was obtained from all individual participants included in the study.