1. Section of Gastroenterology and Hepatology, Dartmouth–Hitchcock Medical Center, Lebanon, New Hampshire, USA.
2. Department of Medicine, Dartmouth Geisel School of Medicine, Hanover, New Hampshire, USA.
3. Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, Massachusetts, USA.
4. Department of Physical Medicine and Rehabilitation, Massachusetts General Hospital, Boston, Massachusetts, USA.
5. Department of Physical Medicine and Rehabilitation, Brigham and Women's Hospital, Boston, Massachusetts, USA.
6. Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Boston, Massachusetts, USA.
7. Galen Medical Group, Chattanooga, Tennessee, USA.
8. Division of Gastroenterology and Hepatology, Oregon Health and Sciences University, Portland, Oregon, USA.