1. Associate Professor, Department of Medicine, College of Medicine, King Saud University and King Khalid University Hospital, P. O. Box 2925, Riyadh 11461, Saudi Arabia
2. Assistant Professor, Department of Medicine, College of Medicine, King Saud University and King Khalid University Hospital, P. O. Box 2925, Riyadh 11461, Saudi Arabia
3. Registrar, Department of Medicine, College of Medicine, King Saud University and King Khalid University Hospital, P. O. Box 2925, Riyadh 11461, Saudi Arabia