[1] Duke Univ Hosp, Neurol, Durham, NC USA
[2] Duke Univ, Margolis Ctr Hlth Policy, Durham, NC USA
[3] Duke Clin Res Inst, Durham, NC USA
[4] Univ Calif Los Angeles, Cardiol, Los Angeles, CA 90024 USA
[5] Harvard Med Sch, Neurol, Boston, MA 02115 USA
[6] AstraZeneca, Biopharmaceut Med, Sodertalje, Sweden
[7] Astrazeneca, Biopharmaceut Med, Cambridge, England
[8] Duke Univ, Sch Med, Orthoped Surg, Durham, NC USA