1. I.H. Page Center for Health Outcomes Research, Cleveland Clinic Foundation, Cleveland, Ohio, USA, Department of Neurology, Cleveland Clinic Foundation, Cleveland, Ohio, USA
2. Department of Neurology, SUNY University of New York at Buffalo, Buffalo General Hospital, Buffalo, USA
3. Department of Neurology, Cleveland Clinic Foundation, Cleveland, Ohio, USA
4. Department of Biostatistics and Epidemiology, Cleveland Clinic Foundation, Cleveland, Ohio, USA
5. I.H. Page Center for Health Outcomes Research, Cleveland Clinic Foundation, Cleveland, Ohio, USA
6. Dipartimento di Neuroscienze, Universita di Torino, Torino, Italy
7. Instituto Nazionale Neurologico C. Besta, Milan, Italy
8. Department of Neurology, Atkinson Morley's Hospital, Wimbledon, London, UK
9. Department of Neurology, Glostrup Hospital, University of Copenhagen, Denmark