[1] MGH, Inst Technol Assessment, Boston, MA 02114 USA
[2] Harvard Univ, Sch Med, Boston, MA 02115 USA
[3] Stanford Univ, Palo Alto, CA 94304 USA
[4] Harvard Univ, Sch Med, Dept Ambulatory Care & Prevent, Boston, MA 02115 USA
[5] Dana Farber Canc Inst, Dept Med Oncol, Boston, MA 02115 USA
[6] Harvard Pilgrim Hlth Care, Boston, MA USA