[1] Vanderbilt Univ, Sch Med, Inst Med & Publ Hlth, Vanderbilt Epidemiol Ctr,Dept Med,Div Gen Interna, Nashville, TN 37203 USA
[2] Univ S Carolina, Norman J Arnold Sch Publ Hlth, Dept Epidemiol & Biostat, Columbia, SC 29208 USA
[3] Shanghai Canc Inst, Dept Epidemiol, Shanghai, Peoples R China