1. Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, Minnesota.
2. Department of Nursing, Mayo Clinic, Rochester, Minnesota.
3. Department of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota.
4. Department of Biostatistics, Mayo Clinic, Rochester, Minnesota.
5. Department of Epidemiology, Mayo Clinic, Rochester, Minnesota.
6. Indiana University School of Medicine, Rehabilitation Hospital of Indiana, Indianapolis, Indiana.