1. Neurology, Public Health and Disability Unit, Neurological Instiute C. Besta, IRCCS Foundation, Milan, Italy;
2. Department of Neuroimmunology and Neuromuscular Diseases, Neurological Institute C. Besta, IRCCS Foundation, Milan, Italy;
3. Unit of Neuroepidemiology, Neurological Institute C. Besta, IRCCS Foundation, Milan, Italy;
4. Scientific Directorate, Neurological Institute C. Besta, IRCCS Foundation, Milan, Italy;
5. Scientific Research Area, Italian Foundation of Multiple Sclerosis, Genoa, Italy