1 University of Trento and Santa Chiara Hospital, Trento, Italy.
2 Rheumatology Department, Brest Teaching Hospital, Brest, France.
3 Division of Clinical Trials and Biostatistics, Department of Quantitative Health Sciences, and Division of Rheumatology, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA.
4 Division of Rheumatology, and Division of Epidemiology, Department of Health Sciences Research, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, USA. [email protected].