1. Amgen Inc., One Amgen Center Drive, Thousand Oaks, CA 91320-1799, USA
2. Wade Outcomes Research and Consulting, 358 South 700 East, Suite B432, Salt Lake City, UT 84102, USA
3. Q.D. Research, Inc., 8789 Auburn Folsom Road, Suite C501, Granite Bay, CA 95746, USA
4. Division of Rheumatology and Clinical Immunology, University of Maryland School of Medicine, 10 S. Pine Street, MSTF 8-34, Baltimore, MD 21201, USA