1. Department of Pediatrics and Rainbow Babies and Children’s Hospital, Case Western Reserve University School of Medicine, Cleveland, Ohio;
2. Vanderbilt University School of Medicine and Monroe Carell Jr Children’s Hospital at Vanderbilt, Nashville, Tennessee;
3. Division of Allergy, Immunology, and Pulmonary Medicine, Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri;
4. Department of Medicine, Brigham and Women’s Hospital and Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts;
5. Heart and Vascular Institute, Cleveland Clinic Foundation, Cleveland, Ohio;
6. Department of Paediatric Respiratory Medicine, Great Ormond Street Hospital, London, United Kingdom;
7. North Middlesex Hospital National Health Service Trust, London, United Kingdom;
8. Evelina Children’s Hospital, Guy’s and St Thomas Hospital, London, United Kingdom;
9. Department of Paediatrics, Imperial College and Imperial College Healthcare National Health Service Trust, London, United Kingdom;
10. Independent statistician, Chicago, Illinois; and
11. University College London Institute of Child Health, London, United Kingdom