1. Centre for Evidence-Based Medicine Odense (CEBMO), University of Southern Denmark and Odense University Hospital, Odense, Denmark.
2. Tobacco Control Research Group, Department for Health, University of Bath, Bath, United Kingdom.
3. Centre for Evidence-Based Medicine Odense (CEBMO) and Cochrane Denmark, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.
4. Open Patient data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark.
5. Department of Infectious Diseases, Hvidovre Hospital, Hvidovre, Denmark.