[1] Duke Clin Res Inst, Durham, NC USA
[2] Duke Univ, Sch Med, Dept Populat Hlth Sci, Durham, NC USA
[3] Duke Univ, Sch Med, Dept Neurol, Durham, NC USA
[4] McGill Univ, Sch Phys & Occupat Therapy, Montreal, PQ, Canada
[5] Texas A&M Univ, Dept Hlth Policy & Management, College Stn, TX USA
[6] PatientsLikeMe, Cambridge, MA USA
[7] Rutgers Robert Wood Johnson Med Sch, Dept Med, New Brunswick, NJ USA