Affiliation: | 1. Wilgeheuwel Hospital, University of the Witwatersrand, Johannesburg, South Africa;2. Roche Products (Pty) Ltd, University of the Witwatersrand, Johannesburg, South Africa;3. School of Public Health, University of the Witwatersrand, Johannesburg, South Africa;4. Division of Rheumatology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa |