1. Department of Community Medicine, Information and Health Decision Sciences, Faculty of Medicine, University of Porto, Porto, Portugal
2. Center for Health Technology and Services Research, Porto, Portugal
3. Basic and Clinical Immunology Unit, Department of Pathology, Faculty of Medicine, University of Porto, Porto, Portugal
4. Division of Rheumatology, Allergy, and Immunology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
5. Harvard Medical School, Boston, Massachusetts, USA
6. Department of Allergy, Southern California Permanente Medical Group, San Diego Medical Center, San Diego, California, USA