[1] Quebec Heart & Lung Inst, Quebec City, PQ, Canada
[2] St Georges Univ London, Populat Hlth Res Inst, London, England
[3] Natl Univ Ireland Galway, Sch Nursing & Midwifery, Galway, Ireland
[4] St Georges Univ London, Populat Hlth Res Inst, London, England