1 Institute of Health and Society, Faculty of Medicine, University of Oslo, Box 1078 Blindern, Oslo, Norway. Electronic address: eivind.engebretsen@medisin.uio.no.
2 Institute of Health and Society, Faculty of Medicine, University of Oslo, Box 1078 Blindern, Oslo, Norway.
3 Partners in Health, Boston, MA, USA.
4 Department of Global Health and Social Medicine, Harvard Medical School, Harvard University, Boston, MA, USA.
5 Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.