Accordingly, a cystatin C-based AKI staging system was developed and its performance studied in critically ill patients.<h4>Methods</h4>AKI stages according to Kidney Disease: Improving Global Outcomes (KDIGO) creatinine criteria were converted to corresponding cystatin C-based stages using 14-day mortality in 9424 critically ill patients from 3 Swedish hospitals followed for 5.6 years (median interquartile range: 2.8-7.2). The gene discussed is CST3; the disease is acute kidney injury.