1. University of Cape Town Groote Schuur Hospital; Department of Medicine; Main Road 7925 Observatory Cape Town Cape Town Western Cape South Africa
2. University of Stellenbosch; Department of Medicine, Division of Rheumatology; Cape Town Tygerberg South Africa 7500
3. School of Medicine; Division of Epidemiology and Public Health; University of Nottingham Nottingham UK NG7 2UH
4. Broadgreen Hospital; Department of Dermatology; Liverpool UK L14 3LB