1. Department of Physical Medicine and Rehabilitation, University of Michigan Health System, Ann Arbor, MI, USA
2. Haig et al. Consulting, Ann Arbor, MI, USA
3. Department of Emergency Medicine, University of Michigan Health System, Ann Arbor, MI, USA
4. Blue Cross Blue Shield of Michigan, Detroit, MI, USA
5. Center for Statistical Consultation and Research, University of Michigan, Ann Arbor, MI, USA