[1] Ottawa Hosp Res Inst, Clin Epidemiol Program, Ottawa, ON, Canada
[2] Univ Ottawa, Sch Epidemiol & Publ Hlth, Ottawa, ON, Canada
[3] Univ Coll Dublin, Hlth Sci Ctr, Sch Med, Belfield, Ireland
[4] Univ Ottawa, Lib Serv, Ottawa, ON, Canada
[5] Hosp Sick Children Res Inst, Child Hlth Evaluat Sci, Toronto, ON, Canada
[6] Ottawa Hosp Res Inst, 501 Smyth Rd,POB 201B, Ottawa, ON K1H 8L6, Canada