[1] Massachusetts Gen Hosp, Gen Med Unit, Div Gen Med, Tobacco Res & Treatment Ctr,Med Serv, Boston, MA 02114 USA
[2] Harvard Univ, Sch Med, Dept Med, Boston, MA 02115 USA
[3] Univ Massachusetts, Surg Res Ctr, Boston, MA 02125 USA
[4] Massachusetts Gen Hosp, Partners HealthCare Syst Inc, Inst Hlth Policy, Boston, MA 02114 USA