1. Institute for Health Services Research in Dermatology and Nursing (IVDP), University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
2. Glasgow Centre for Population Health, Glasgow G40 2QH, UK
3. Department of Health Sciences, Faculty of Life Sciences, Hamburg University of Applied Sciences, 20999 Hamburg, Germany
4. Health Sciences Unit, Faculty of Social Sciences, Tampere University, 33100 Tampere, Finland
5. IBE—Institute for Medical Information Processing, Biometry and Epidemiology, Ludwig-Maximilians-Universität München, 81377 Munich, Germany