[1] Univ Hosp Northern Norway, Fac Hlth Sci, Dept Dermatol, Tromso, Norway
[2] Univ Copenhagen, Fac Hlth Sci, Roskilde Hosp, Dept Dermatol, Copenhagen, Denmark
[3] Karolinska Univ Hosp, Dept Dermatol, SE-14186 Stockholm, Sweden
[4] Karolinska Inst, Dept Med, Unit Infect Dis & Dermatol, SE-14186 Stockholm, Sweden
[5] Soder Sjukhuset, Dermatol Sect, Dept Clin Sci & Educ, Stockholm, Sweden
[6] Reg Hlth Author North Norway, Ctr Clin Documentat & Evaluat SKDE, Tromso, Norway
[7] St Olavs Hosp, Dept Dermatol, Trondheim, Norway
[8] Univ Tromso, Dept Epidemiol, Fac Hlth Sci, Tromso, Norway