1. Center for Clinical Epidemiology and Biostatistics, School of Medicine, University of Pennsylvania, Philadelphia, PA;
2. North Florida/South Georgia Veterans Health System (NF/SG VHS), Gainesville, FL;
3. Department of Health Outcomes and Policy, College of Medicine, University of Florida, Gainesville, FL;
4. Samuel S. Stratton VA Medical Center, Albany, NY; and Department of Physical Medicine and Rehabilitation, Albany Medical College, Albany, NY