Funding for this research was provided by:
University College London
Article History
Received: 3 July 2019
Accepted: 26 November 2019
First Online: 10 January 2020
Compliance with ethical guidelines
:
: J. Leung, A. Ng and K. Gurusamy declare that they have no competing interests.
: This is a study on research methodology of guidelines, thus no inclusion of people for the study. All the studies cited by the guidelines also did not include any people for the study.