1. Department of Anesthesia & Intensive Care, Odense University Hospital, Odense C, Denmark, and Institute for Clinical Research Anesthesiology, University of Southern Denmark, Odense C
2. Department of Public Health, University of Southern Denmark
3. Department of Paediatrics, Lillebaelt Hospital, Kolding, and Epidemiology, Institute of Public Health, University of Southern Denmark
4. University of Southern Denmark, Odense C, Denmark, and Consultant Pediatric Anesthesiologist, Department of Anesthesia & Intensive Care, Odense University Hospital, Odense C, Denmark
5. Department of Health Management and Policy, College of Public Health, University of Iowa, Iowa City, Iowa.