aDivision of Rheumatology, Department of Internal Medicine III; Medical University of Vienna

bLudwig Boltzmann Institute for Arthritis and Rehabilitation, Vienna, Austria

cDepartment of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands

Correspondence to Günter Steiner, PhD, Division of Rheumatology, Department of Internal Medicine III, Medical University of Vienna, Währinger Gürtel 18-20, A 1090 Vienna, Austria. Tel +43 1 40400 43010;. fax:+43 1 40400 4306; e-mail: [email protected]