1. a Gender & Health Research Unit , Medical Research Council , PO Box 19070, Tygerberg 7405, Cape Town , South Africa
2. b Gender & Health Research Unit , Medical Research Council , Pretoria , South Africa
3. c Biostatistics Unit , Medical Research Council , Cape Town , South Africa
4. d Johns Hopkins University School of Nursing , Baltimore , MD , USA
5. e Department of Forensic Medicine, Faculty of Health Sciences , Walter Sisulu University , Mthatha , South Africa