1 Arthritis Unit, Rheumatology Department, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS) and University of Barcelona, Barcelona, Spain. Electronic address: jagomez@clinic.cat.
2 Arthritis Unit, Rheumatology Department, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS) and University of Barcelona, Barcelona, Spain.