1. Pain Research Unit, Churchill Hospital; Cochrane Pain, Palliative and Supportive Care Group; Oxford UK
2. University of Washington; Anesthesiology and Pain Medicine; Seattle Washington USA
3. Seattle Children's Research Institute; Center for Child Health, Behavior, and Development; 2001 8th Avenue, Suite 400 Seattle Washington USA
4. University of Bath; Centre for Pain Research; Claverton Down Bath UK