1. Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden;
2. Department of Nephrology, Sahlgrenska University Hospital, Gothenburg, Sweden;
3. Department of Statistics, Umeå University, Umeå, Sweden;
4. Department of Pediatrics, Sunderbyn Hospital, Luleå, Sweden;
5. Department of Internal Medicine, Ryhov County Hospital, Jönköping, Sweden;
6. Department of Public Health and Clinical Medicine, Epidemiology and Public Health Sciences, Umeå University, Umeå, Sweden;
7. Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.