1. UK Cochrane Centre; National Institute for Health Research Summertown Pavilion, Middle Way Oxford Oxfordshire UK OX2 7LG
2. Monash Institute of Health Services Research; Australasian Cochrane Centre; Monash Medical Centre Locked Bag 29 Clayton Victoria Australia 3168
3. Institute of Social and Preventive Medicine; Department of Social Medicine; Finkenhubelweg 11 Bern Switzerland 3012