Value of the RIFLE classification for acute kidney injury in diffuse proliferative lupus nephritis

Background. There are many studies on the RIFLE classification to evaluate the occurrence rate and/or outcome of acute kidney injury (AKI) in ICU patients, but there are no studies on the RIFLE classification to evaluate the outcome of AKI in lupus patients. Methods. This retrospective study analysed the short-term outcomes of 79 diffuse proliferative lupus nephritis patients according to the RIFLE classification. Results. A total of 46% of patients were No AKI, 23% AKI-R, 16% AKI-I and 15% AKI-F according to the maximum RIFLE class reached on the first day of admission. The percentage of progression of AKI to the more severe RIFLE class was 6% for AKI-R, 23% for AKI-I and 75% for AKI-F (P < 0.0001), and there was an increased odds ratio (OR) of progression rate with more severe RIFLE category (OR 7.7, 95% CI 2.3-25.7, P < 0.001). The recovery rate at the end of a 24-week follow-up was 100% for AKI-R, 92% for AKI-I and 33% for AKI-F (P < 0.0001). The mean time to recovery for the groups AKI-R, AKI-I and AKI-F was 4, 11 and 20 weeks, respectively (P < 0.0001). The area under the ROC curve for progression to chronic kidney disease (CKD) was 0.96 (95% CI 0.91-1.0, P < 0.001). Conclusion. The RIFLE classification is predictive of progression and short-term prognosis of AKI in diffuse proliferative lupus nephritis.