1 Divisio n of Rheumatology, Department of Medicine.
2 Department of Pathology.
3 Division of Hematology and Oncology, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia.
4 Chester County Rheumatology, West Chester.
5 Division of Clinical Epidemiology, Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.