1. University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA (HJ)
2. The Hospital for Sick Children, Toronto and University of Toronto, Toronto, Ontario, Canada (PP)
3. Erasmus MC, Rotterdam, the Netherlands (EK)
4. University of Minnesota School of Public Health, Minneapolis, MN, USA (FA-E, EE)
5. Erasmus MC, Rotterdam, The Netherlands and Harvard T.H. Chan School of Public Health, Boston, MA, USA (MGMH)