Article History
Received: 21 May 2019
Accepted: 7 September 2019
First Online: 18 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 certificate M180709), This was a de-identified analysis of an existing database, and so consent to participate was not required.
: Not applicable.
: The authors declare that they have no competing interests.