[1] Sydney Childrens Hosp, Pain Res Unit, Randwick, NSW 2031, Australia
[2] Univ New S Wales, Sch Psychol, Sydney, NSW, Australia
[3] Sydney Childrens Hosp, Ctr Childrens Canc & Blood Disorders, Randwick, NSW 2031, Australia
[4] Univ Saskatchewan, Dept Psychol, Saskatoon, SK S7N 0W0, Canada
[5] Univ Saskatchewan, Dept Pediat, Saskatoon, SK S7N 0W0, Canada