[1] Ctr Pain Hlth & Lifestyle, New Lambton Hts, NSW, Australia
[2] Univ Sydney, Sch Publ Hlth, Sydney, NSW, Australia
[3] Keele Univ, Inst Primary Care & Hlth Sci, Arthrit Res UK Primary Care Ctr, Keele, Staffs, England
[4] St George Hosp, South Staffordshire & Shropshire NHS Fdn Trust, Stafford, Staffs, England
[5] Hunter New England Local Hlth Dist, Hunter New England Populat Hlth, Wallsend, Tyne & Wear, Australia
[6] Univ Newcastle, Hunter Med Res Inst, Sch Med & Publ Hlth, Newcastle, NSW, Australia