[1] Kings Coll London, Florence Nightingale Sch Nursing & Midwifery, London, England
[2] Univ N Carolina, Ctr Funct GI & Motil Disorders, Chapel Hill, NC 27599 USA
[3] Univ Minnesota, Sch Nursing, Minneapolis, MN 55419 USA
[4] St Thomas Hosp, Dept Ageing & Hlth, Guys & St Thomas Hosp NHS Fdn Trust, London SE1 7EH, England