[1] Amer Legacy Fdn, Schroeder Inst Tobacco Res & Policy Studies, Washington, DC USA
[2] Georgetown Univ, Med Ctr, Div Pulm & Crit Care, Washington, DC 20007 USA
[3] Georgetown Univ, Med Ctr, Lombardi Comprehens Canc Ctr, Washington, DC 20007 USA
[4] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Hlth Behav & Soc, Baltimore, MD USA