1. Sutter Health Center for Health Systems Research, Walnut Creek, CA, USA
2. Kaiser Permanente Division of Research, Oakland, CA, USA
3. Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA USA
4. Department of Medicine, University of California San Francisco, San Francisco, CA, USA
5. Albert Einstein College of Medicine and the Montefiore Headache Center, Bronx, NY, USA
6. PRECISIONheor, Boston, MA, USA