[1] McGill Univ, Dept Epidemiol Biostat & Occupat Hlth, Montreal, PQ, Canada
[2] London Sch Hyg & Trop Med, Dept Global Hlth & Dev, Social & Math Epidemiol Grp, London WC1, England
[3] London Sch Hyg & Trop Med, Gender Violence & Hlth Ctr, Dept Global Hlth & Dev, London WC1, England
[4] Johns Hopkins Univ, Sch Nursing, Dept Community Publ Hlth, Baltimore, MD USA