[1] Med Univ Lubeck, Dept Social Med, D-23552 Lubeck, Germany
[2] Tech Univ Munich, Dept Dermatol & Allergy, D-8000 Munich, Germany
[3] Univ Munich, Inst Epidemiol, GSF, Natl Res Ctr Environm & Hlth, Munich, Germany
[4] Univ Munich, Inst Med Data Proc Biomet & Epidemiol, Munich, Germany