1. University of Dundee Medical School, Dundee, United Kingdom;Ninewells Hospital, Dundee, United Kingdom;
2. Frenchay Hospital, Bristol, United Kingdom;
3. St Vincent's University Hospital, Dublin, Ireland;
4. Nottingham City Hospital, Nottingham, United Kingdom; University of Nottingham, Nottingham, United Kingdom;
5. Aberdeen Royal Infirmary, Aberdeen, United Kingdom;
6. Hammersmith Hospital, London, United Kingdom;
7. University of Aberdeen Health Services Research Unit, Aberdeen, United Kingdom;
8. Inverclyde Royal Hospital, Greenock, United Kingdom;
9. United Kingdom Cochrane Centre, Oxford, United Kingdom;
10. Leeds General Infirmary, Leeds, United Kingdom;University of Leeds, Leeds, United Kingdom