1 Division of Rheumatology, Department of Medicine, Rush University School of Medicine, Chicago, IL 60612, USA.
2 Department of Biostatistics, Bioinformatics & Biomathematics, Georgetown University, Washington, DC 20057, USA.
3 Department of Rheumatology, Hospital Clinic Universitari de Barcelona, Institut d´investigacions Biomèdiques August Pi i Sunyer, Barcelona 08036, Spain.
4 Division of Rheumatology, Department of Medicine, Rush University School of Medicine, Chicago, IL 60612, USA. Electronic address: tedpincus@gmail.com.