1. Rheumatology Department, University of Málaga (UMA), Málaga, Spain
2. Grup de Recerca de Reumatologia, Institut de Recerca, Hospital Vall d'Hebron, Barcelona, Spain
3. Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, AL 35226, USA
4. Centre for Rheumatology, Division of Medicine, University College London, London, UK