[1] Minist Hlth, Natl Ctr Lab & Epidemiol, Viangchan, Laos
[2] Minist Hlth, Viangchan, Laos
[3] Minist Hlth, Lao Trop & Publ Hlth Inst, Viangchan, Laos
[4] Minist Hlth, Dept Hyg & Hlth Promot, Viangchan, Laos
[5] Oklahoma Med Res Fdn, 825 NE 13th St, Oklahoma City, OK 73104 USA
[6] Univ Oklahoma, Hlth Sci Ctr, Dept Family & Prevent Med, Oklahoma Tobacco Res Ctr,Stephenson Canc Ctr, Oklahoma City, OK 73104 USA