1. Epidemiology and Public Health Sciences, Department of Public Health and Clinical Medicine, UmeÅ University, UmeÅ, Sweden, Center for Clinical Research Dalarna, Falun, Sweden, Research Department, National Institute of Public Health - Sweden, Stockholm, Sweden,
2. Department of Health and Social Sciences, Dalarna University, Falun, Sweden
3. Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden
4. Epidemiology and Public Health Sciences, Department of Public Health and Clinical Medicine, UmeÅ University, UmeÅ, Sweden, Research Department, National Institute of Public Health - Sweden, Stockholm, Sweden
5. Epidemiology and Public Health Sciences, Department of Public Health and Clinical Medicine, UmeÅ University, UmeÅ, Sweden, Pediatrics, Department of Clinical Sciences, UmeÅ University, UmeÅ, Sweden