[1] Univ Washington, Dept Epidemiol, Seattle, WA 98195 USA
[2] Univ Sherbrooke, Dept Med, Sherbrooke, PQ J1K 2R1, Canada
[3] Univ Sherbrooke, Dept Clin Sci, Sherbrooke, PQ J1K 2R1, Canada
[4] McGill Univ, Jewish Gen Hosp, Ctr Clin Epidemiol & Community Studies, Montreal, PQ H3T 1E2, Canada