[1] RAND Corp, RAND Hlth, Pittsburgh, PA USA
[2] RAND Corp, RAND Hlth, Arlington, VA USA
[3] ABT Associates Inc, Cambridge, MA 02138 USA
[4] Univ N Carolina, Dept Epidemiol, Gillings Sch Global Publ Hlth, Chapel Hill, NC USA
[5] Univ N Carolina, Sch Med, Dept Med, Chapel Hill, NC USA
[6] RAND Corp, RAND Hlth, Santa Monica, CA USA
[7] Univ Minnesota, Dept Med, Minneapolis, MN 55455 USA
[8] HealthPartners Res Fdn, Minneapolis, MN USA
[9] Univ Massachusetts, Sch Med, Dept Med, Div Prevent & Behav Med, Worcester, MA USA
[10] Drexel Univ, Sch Publ Hlth, Dept Epidemiol & Biostat, Philadelphia, PA 19104 USA
[11] Harvard Univ, Brigham & Womens Hosp, Sch Med, Dept Prevent Med, Boston, MA 02115 USA
[12] Univ Calif Los Angeles, Dept Med, Div Gen Internal Med & Hlth Serv Res, Los Angeles, CA 90024 USA