Received: 25 July 2018
Accepted: 3 September 2019
First Online: 7 September 2019
Ethics approval and consent to participate
: The study was approved by the Human Research Ethics Committee of the University of the Witwatersrand (Clearance Number M 15 1108). This was a retrospective record review of de-identified data so consent to participate was not required.
: Not applicable.
: The authors declare that they have no competing interests.