1. Department of Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
2. Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark
3. Department of Dermatology, Aarhus University Hospital, Aarhus N, Denmark
4. Department of Dermatology, University of California, San Francisco
5. Department of Medical Statistics, London School of Hygiene and Tropical Medicine, London, United Kingdom
6. Centre for Longitudinal Studies, Department of Social Science, University College London, London, United Kingdom
7. Health Data Research UK, London, United Kingdom