1. Institute of General Practice and Community Medicine and Institute for Surgical Research; Oslo University Hospital; Oslo Norway
2. Department of Paediatrics; Oslo University Hospital and University of Oslo; Oslo Norway
3. Department of Community Medicine; University of Oslo; Oslo Norway
4. Tibet University Medical College; Lhasa China
5. Department for Public Health; Hedmark University College; Elverum Norway
6. Innlandet Hospital Trust; Hamar Norway