1. Institute for Health Research, Kaiser Permanente Colorado, Denver, CO 80231, USA
2. Department of Medicine, University of Colorado, Aurora, CO 80309, USA
3. Group Health Research Institute, Seattle, WA 98101, USA
4. Division of Research, Kaiser Permanente Northern California, Oakland, CA 94612, USA
5. Skaggs School of Pharmacy & Pharmaceutical Sciences, University of Colorado, Aurora, CO 80045, USA