[1] Univ British Columbia, Sch Populat & Publ Hlth, Vancouver, BC, Canada
[2] British Columbia Ctr Dis Control, Data & Analyt Serv, Vancouver, BC, Canada
[3] Univ British Columbia, Fac Med, Ctr Dis Control, Vancouver, BC, Canada
[4] Univ British Columbia, Div Gastroenterol, Vancouver, BC, Canada
[5] Ohio Univ, Heritage Coll Osteopath Med, Dept Social Med, Dublin, OH USA
[6] St Pauls Hosp, Ctr Adv Hlth, Vancouver, BC, Canada