[1] Oregon Hlth & Sci Univ, Dept Med, Smoking Cessat Ctr, Portland, OR 97239 USA
[2] Univ Nebraska Med Ctr, Pulm Div, Omaha, NE USA
[3] Univ Wisconsin, Sch Med & Publ Hlth, Ctr Tobacco Res & Intervent, Madison, WI USA
[4] Pfizer Global Res & Dev, Groton, CT USA