Toward a Unified Definition of Progression Independent of Relapse Activity in Multiple Sclerosis.

Portaccio E, Betti M, De Meo E, Pastò L, Prestipino E, Lugaresi A, Cocco E, De Luca G, Patti F, Torri Clerici VLAM, Ferraro D, Brescia Morra V, Salemi G, Vianello M, Cerqua R, Inglese M, Pasanisi MB, Perini P, Romano S, Pozzilli C, Tortorella C, Di Sapio A, Annovazzi P, Simone M, Iaffaldano P, Rocca MA, Filippi M, Trojano M, Amato MP; Italian Multiple Sclerosis and Related Disorders Register.