1. The Pulmonary Center; Boston University School of Medicine; Boston MA USA
2. Center for Health Quality, Outcomes and Economic Research; ENRM VA Hospital; Bedford MA USA
3. Department of Research and Evaluation; Kaiser Permanente Southern California; Pasadena CA USA
4. Outcomes Group; VA Hospital; White River Junction VT USA
5. The Dartmouth Institute for Health Policy & Clinical Practice; Dartmouth Medical School; Hanover NH USA
6. Department of Health Policy & Management; Boston University School of Public Health; Boston MA USA