[1] Norwegian Univ Sci & Technol, Fac Med & Hlth Sci, Dept Mental Hlth, N-7491 Trondheim, Norway
[2] Norwegian Univ Sci & Technol, Fac Med & Hlth Sci, Dept Publ Hlth & Nursing, Trondheim, Norway
[3] Norwegian Ctr E Hlth Res, Tromso, Norway
[4] Trondheim Reg & Univ Hosp, St Olavs Hosp, Norwegian Advisory Unit Complex Symptom Disorders, Trondheim, Norway