1. Rigshospitalet, University Hosital of Copenhagen, Denmark.
2. Skejby Sygehus, Aarhus, Denmark.
3. Odense University Hospital, Odense, Denmark.
4. Aalborg Hospital, Aalborg, Denmark.
5. Kolding Hospital, Denmark.
6. Herning Hospital, Denmark.
7. Department of Clinical Epidemiology, Århus University Hospital, Århus, Denmark.