1. Center for Health Quality, Outcomes, and Economic Research, Edith Nourse Rogers Memorial Veterans Hospital, Bedford, Mass and Section of General Internal Medicine, Boston Medical Center, Boston, Mass and Boston University Schools of Medicine and Public Health, Boston, Mass,
2. Management Decision and Research Center, Boston VAMC, Boston, Mass and Boston University Schools of Medicine and Public Health, Boston, Mass
3. Center for Health Quality, Outcomes, and Economic Research, Edith Nourse Rogers Memorial Veterans Hospital, Bedford, Mass and Boston University Schools of Medicine and Public Health, Boston, Mass
4. Section of General Internal Medicine, Boston Medical Center, Boston, Mass and Boston University Schools of Medicine and Public Health, Boston, Mass