1. Department of Pediatrics, Heart Institute, University of Cincinnati College of Medicine, Cincinnati, OH
2. Heart Center at the Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL
3. Department of Pediatrics and Medical Social Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL
4. Division of Biostatistics and Epidemiology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH
5. Department of Clinical Epidemiology, University of Aarhus, Aarhus, Denmark