[1] Univ Minnesota, Sch Publ Hlth, Div Epidemiol & Community Hlth, 1300S 2nd St, Minneapolis, MN 55455 USA
[2] Univ Minnesota, Sch Publ Hlth, Div Biostat, Minneapolis, MN 55455 USA
[3] Princeton Univ, Univ Hlth Serv, Princeton, NJ 08544 USA
[4] Fred Hutchinson Canc Res Ctr, Vaccine & Infect Dis Div, 1124 Columbia St, Seattle, WA 98104 USA
[5] Univ Washington, Dept Biostat, Sch Publ Hlth, Seattle, WA 98195 USA
[6] McGill Univ, Dept Epidemiol Biostat & Occupat Hlth, Fac Med, Montreal, PQ, Canada