[1] Queens Univ Belfast, Sch Nursing & Midwifery, Belfast BT9 5AF, Antrim, North Ireland
[2] Univ Toulouse 3, INSERM, Fac Med, F-31062 Toulouse, France
[3] Univ Newcastle, Inst Hlth & Soc, Newcastle Upon Tyne, Tyne & Wear, England
[4] Univ Klinikum Schleswig Holstein, Klin Kinder & Jugendmed, Lubeck, Germany
[5] Univ Gothenburg, Queen Silvia Childrens Hosp, Gothenburg, Sweden
[6] Univ Grenoble 1, SIIM Pole Exploitat, Grenoble, France
[7] Azienda Sanitaria Locale Viterbo, Viterbo, Italy
[8] Enable Ireland, Cork, Ireland
[9] Natl Inst Publ Hlth, Copenhagen, Denmark
[10] Univ Newcastle, Sch Clin Med Sci, Newcastle Upon Tyne, Tyne & Wear, England
[11] Univ Newcastle, Royal Victoria Infirm, Sir James Spence Inst, Newcastle Upon Tyne, Tyne & Wear, England