[1] Harvard Univ, Sch Med, Dept Ambulatory Care & Prevent, Boston, MA 02215 USA
[2] Harvard Univ, Pilgrim Hlth Care, Boston, MA 02215 USA
[3] St Josephs Hosp, Ctr Evaluat Med, Hamilton, ON, Canada
[4] McMaster Univ, Hamilton, ON, Canada
[5] Univ Massachusetts, Med Ctr, Meyers Primary Care Inst, Worcester, MA USA
[6] Fallon Healthcare Syst, Worcester, MA USA
[7] Harvard Univ, Sch Med, Dept Hlth Care Policy, Boston, MA 02115 USA
[8] Brigham & Womens Hosp, Div Cardiovasc, Boston, MA 02115 USA
[9] Healthcare Educ & Res Fdn, St Paul, MN USA