Article History
Accepted: 28 July 2018
First Online: 7 August 2018
Compliance with ethical standards
:
: All authors declare that they have no conflict of interest.
: The study was approved by the Health Research Ethics Committee of Stellenbosch University, Cape Town (HREC# S14/08/163) and all participants provided written informed consent before commencing. All procedures were performed in accordance with the ethical standards of the institutional committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.