[1] Oslo & Akershus Univ, Coll Appl Sci, Dept Nursing, Fac Hlth Sci, N-0130 Oslo, Norway
[2] Oslo & Akershus Univ, Coll Appl Sci, Fac Social Sci, N-0130 Oslo, Norway
[3] London Sch Hyg & Trop Med, Dept Hlth Serv Res & Policy, London WC1H 9SH, England
[4] Univ Oslo, Dept Social Anthropol, Fac Social Sci, N-0317 Oslo, Norway