1. RAND Health, Santa Monica, California,
2. RAND Health, Santa Monica, California
3. RAND Health, Santa Monica, and in the Division of General Internal Medicine, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California
4. RAND Health, Santa Monica; VA Greater Los Angeles Healthcare System; and the Division of General Internal Medicine and Health Services Research, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California