 Method: This cohort study uses Swedish national healthcare registers to investigate the epidemiology of acute kidney injury. The Swedish Intensive Care Register SIR provides the population base, with data extraction between 2005 and 2011. The information obtained is cross-matched by the Swedish board for health and welfare Social Styrelsen with other national registries. All data are returned anonymized and individual patients can not be identified in any way. Additionally analysis is performed on a group and not on an individual basis. The key to this data is held by Swedish board for health and welfare. The other national registries include the Swedish Cause of Death Register Dödsregister, the Swedish renal register Svensknjurregistret and the in and out-patients registers Öppen- slutenvårdsregister these are used to obtain data on all cause mortality, co-morbidities, Pre and Post ICU CKD and ESRD. Epidemiological methods are used to analyse the data. 