[1] Cleveland Clin Fdn, Mellen Ctr Multiple Sclerosis, Cleveland, OH USA
[2] Cleveland Clin, Dept Neurol, Cleveland, OH USA
[3] Case Western Reserve Univ, Dept Populat & Quantitat Hlth Sci, Cleveland, OH USA
[4] Cleveland Clin, Lou Ruvo Ctr Brain Hlth, Las Vegas, NV USA