1. VA San Diego Healthcare System, San Diego, CA, USA
2. University of California San Diego, San Diego, CA, USA
3. VA Palo Alto Healthcare System, Palo Alto, CA, USA
4. Stanford University School of Medicine, Palo Alto, CA, USA
5. Edith Nourse Rogers Memorial Veterans Hospital, Bedford, MA, USA
6. Boston University Schools of Public Health and Medicine, Boston, MA, USA