1. Institute of Social and Preventive Medicine (ISPM), University of BernFinkenhubelweg 11BernCH‐3012 Switzerland
2. Department of PediatricsUniversity of BernFreiburgstrasse 4BernCH‐3010 Switzerland
3. Department of Pediatrics, Oncology and Hematology UnitGeneva University HospitalRue Willy‐Donzé 6CH‐1205Genève Switzerland
4. Department of Health Sciences and Health PolicyUniversity of LucerneFrohburgstrasse 3, P.O. Box 4466LucerneCH‐6002 Switzerland