[1] Akershus Univ Hosp, Res Ctr, NO-1478 Lorenskog, Norway
[2] Univ Oslo, Inst Hlth & Soc, Dept Hlth Management & Hlth Econ, Oslo, Norway
[3] Univ Bergen, Dept Publ Hlth & Primary Hlth Care, Bergen, Norway
[4] Indiana Univ Sch Med, VA HSR&D Ctr Excellence, Roudebush VA Med Ctr, Indianapolis, IN 46202 USA
[5] Univ Oslo, Inst Clin Med, Lorenskog, Norway