[1] Univ Calif San Francisco, Healthforce Ctr, Philip R Lee Inst Hlth Policy Studies, Dept Family & Community Med, San Francisco, CA 94143 USA
[2] Univ N Carolina, Dept Hlth Policy & Management, Gillings Sch Global Publ Hlth, Chapel Hill, NC 27515 USA
[3] Dartmouth Coll, Geisel Sch Med, Dartmouth Inst Hlth Policy & Clin Practice, Hanover, NH 03755 USA
[4] Yale Univ, Sch Publ Hlth, New Haven, CT USA