[1] Univ Oslo, Dept Dermatol, Oslo Univ Hosp, Rikshosp,Fac Med, N-0027 Oslo, Norway
[2] Univ Oslo, Inst Gen Practice & Community Med, N-0027 Oslo, Norway
[3] Harvard Univ, Beth Israel Deaconess Med Ctr, Sch Med, Boston, MA 02215 USA
[4] Univ Oslo, Dept Biostat, Inst Basic Med Sci, N-0027 Oslo, Norway
[5] Tibet Univ, Coll Med, Lhasa, Tibet, Peoples R China
[6] Univ Oslo, Inst Psychiat, N-0027 Oslo, Norway