[1] Harvard Univ, Sch Med, Boston, MA 02215 USA
[2] Harvard Pilgrim Hlth Care, Eth Program, Dept Ambulatory Care & Prevent, Boston, MA 02215 USA
[3] Tufts Univ, Dept Philosophy, Medford, MA 02155 USA
[4] Tufts Univ, Sch Med, Dept Social Med, Boston, MA 02111 USA