1 VA HSR&D Center for the Study of Healthcare Innovation, Implementation and Policy, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA. emshannon@mednet.ucla.edu.
2 Division of General Internal Medicine and Health Services Research, David Geffen School of Medicine at University of California, Los Angeles, CA, USA. emshannon@mednet.ucla.edu.
3 VA HSR&D Center for the Study of Healthcare Innovation, Implementation and Policy, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA.
4 Veterans Emergency Management Evaluation Center, US Department of Veterans Affairs, North Hills, CA, USA.
5 Division of General Internal Medicine and Health Services Research, David Geffen School of Medicine at University of California, Los Angeles, CA, USA.