1. Institute for Health Research, Kaiser Permanente Colorado, Aurora, Colorado.
2. Department of Pharmacy, Kaiser Permanente Colorado, Denver, Colorado.
3. Regional Laboratory, Colorado Permanente Medical Group, Denver, Colorado.
4. Department of Rheumatology, Colorado Permanente Medical Group, Lafayette, Colorado.
5. Quality and Safety Systems Branch, Division of Laboratory Systems, Centers for Surveillance, Epidemiology, and Laboratory Services, Centers for Disease Control and Prevention, Atlanta, Georgia.