1. Center for Healthcare Organization and Implementation Research, VA Bedford Healthcare System, Bedford, Massachusetts, USA.
2. The Pulmonary Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
3. Pulmonary and Critical Care Medicine Section, VA Boston Healthcare System, Boston, Massachusetts, USA.
4. Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA.
5. VA Connecticut Healthcare System, West Haven, Connecticut, USA.
6. Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, USA.