1. School of Medical Sciences, Örebro University , Örebro , Sweden
2. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet , Sweden
3. Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet , Stockholm , Sweden
4. Division of Nephrology, Department of Medicine, Stanford University School of Medicine , USA
5. Division of Nephrology, RWTH Aachen University Hospital , Aachen , Germany