1. Moss Rehabilitation Research Institute, Elkins Park, Pennsylvania.
2. Department of Health Evidence and Policy and Center for Biostatistics, Icahn School of Medicine at Mount Sinai, New York, New York.
3. Department of Physical Medicine & Rehabilitation, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
4. Department of Rehabilitation Medicine, University of Washington, Seattle, Washington.
5. G.H. Sergievsky Center, Columbia University, New York, New York.
6. Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham, Birmingham, Alabama.
7. Harvard Medical School, Spaulding Rehabilitation Hospital, Massachusetts General Hospital, Boston, Massachusetts.