1. Department of Physical Therapy School of Health Professions, University of Alabama at Birmingham Birmingham Alabama USA
2. Physical Medicine and Rehabilitation, School of Medicine Johns Hopkins University Baltimore Maryland USA
3. Department of Physical Therapy University of Nevada, Las Vegas Las Vegas Nevada USA
4. Department of Nursing Johns Hopkins Hospital Baltimore Maryland USA
5. Department of Physical Medicine and Rehabilitation Johns Hopkins Hospital Baltimore Maryland USA
6. Department of Biostatistics Johns Hopkins Bloomberg School of Public Health Baltimore Maryland USA
7. Division of Pulmonary and Critical Care Medicine School of Medicine, Johns Hopkins University Baltimore Maryland USA