[1] Univ Regensburg, Inst Epidemiol & Prevent Med, Dept Med Sociol, Dr Gessler Str 17, D-93051 Regensburg, Germany
[2] Vrije Univ Amsterdam Med Ctr, Dept Epidemiol & Biostat, EMGO Inst Hlth & Care Res, Amsterdam, Netherlands
[3] Univ East Anglia, Norwich Med Sch, Norwich, Norfolk, England
[4] Brown Univ, Warren Alpert Med Sch, Dept Dermatol, Providence, RI 02912 USA
[5] Univ Heidelberg Hosp, Dept Clin Social Med, Heidelberg, Germany
[6] Guys & St Thomas NHS Fdn Trust, St Johns Inst Dermatol, London, England
[7] Kings Coll London, London, England
[8] Brighton & Sussex Med Sch, Div Publ Hlth & Primary Care, Falmer, England