1 Department of rheumatology, Pitié-Salpêtrière hospital, AP-HP, 75013 Paris, France; Department of internal medicine, institut mutualiste Montsouris, 75014 Paris, France. Electronic address: stephane.mitrovic@yahoo.fr.
2 Department of rheumatology, Pitié-Salpêtrière hospital, AP-HP, 75013 Paris, France.
3 Department of rheumatology, Pellegrin hospital, Bordeaux university hospital, 33000 Bordeaux, France.
4 Department of rheumatology, Pitié-Salpêtrière hospital, AP-HP, 75013 Paris, France; Sorbonne universités, UPMC university Paris 06, institut Pierre-Louis d'épidémiologie et de sante publique, GRC-UPMC 08 (EEMOIS), 75006 Paris, France.