1. VA Connecticut Healthcare System, West Haven, CT, Department of Neurosurgery, Yale University, New Haven, CT,
2. Department of Internal Medicine and the Center for Clinical Effectiveness at the Institute for Health Policy and Health Services Research, University of Cincinnati Medical Center, Cincinnati, OH, Veterans Affairs Medical Center, Cincinnati, OH
3. Department of Health Policy and Management, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, Center for Research on Health Care, University of Pittsburgh, Pittsburgh, PA
4. Department of Medicine and the Division of General Internal Medicine, University of Pittsburgh, Pittsburgh, PA, Center for Research on Health Care, University of Pittsburgh, Pittsburgh, PA