1. Rheumatology Unit, The Queen Elizabeth Hospital, 28 Woodville Road, Woodville South, SA 5011, Australia
2. University of Adelaide, Adelaide, SA 5005, Australia
3. Arthritis South Australia, 118 Richmond Road, Marleston, SA 5033, Australia
4. Department of Social and Behavioral Sciences, Harvard School of Public Health, 677 Huntington Avenue, Kresge Building 7th Floor, Boston, MA 02115, USA
5. Population Research & Outcomes Unit, University of Adelaide, Adelaide, SA 5005, Australia