Effects of physical comorbidities on disability progression in multiple sclerosis.

Zhang T, Tremlett H, Zhu F, Kingwell E, Fisk JD, Bhan V, Campbell T, Stadnyk K, Carruthers R, Wolfson C, Warren S, Marrie RA; CIHR Team in the Epidemiology and Impact of Comorbidity on Multiple Sclerosis.