1. Department of Medicine, William Beaumont Hospital, Royal Oak, USA.
2. Division of Rheumatology, Department of Medicine, University of Michigan Medical School, Ann Arbor, USA.
3. Division of Rheumatology, Department of Medicine, University of Michigan Medical School, Ann Arbor, and School of Public Health, University of Michigan Medical School, Ann Arbor, USA.
4. Division of Rheumatology, Department of Medicine, University of Michigan Medical School, Ann Arbor, USA. khannad@med.umich.edu