[1] Washington Univ, Sch Med, Div Biostat, St Louis, MO 63110 USA
[2] Washington Univ, Sch Med, St Louis, MO USA
[3] Univ Chile, Hosp Clin, Santiago, Chile
[4] Clin Alemana Santiago, Santiago, Chile
[5] Washington Univ, Sch Med, Dept Neurol, St Louis, MO USA
[6] Washington Univ, Sch Med, Dept Pathol & Immunol, St Louis, MO USA
[7] Washington Univ, Sch Med, Dept Phys Therapy, St Louis, MO USA