1. Division of Rheumatology, Department of Medicine, College of Medicine, King Khalid University Hospital, King Saud University, P.O. Box 2925, Riyadh 11461, Saudi Arabia
2. Division of Rheumatology, Department of Medicine, Qatif Central Hospital, Qatif, Saudi Arabia
3. Department of Pathology, College of Medicine, King Saud University, Riyadh, Saudi Arabia