1 Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA.
2 Departments of Neurology, Internal Medicine, and the Center for Neuroepidemiological and Clinical Neurological Research, Yale School of Medicine, New Haven, Connecticut, USA.
3 Neurology Service and Pain Research, Informatics, Multi-morbidities, and Education (PRIME) Health Services Research Center, VA Connecticut Healthcare System, West Haven, Connecticut, USA.
4 Department of Neurology, Division of Headache, Yale School of Medicine, New Haven, Connecticut, USA.