MO335: Reaching SCR 4.0 mg/dL, the Magical Number for KDIGO-2012 AKI Stage 3. Is it Adequate for Stratifying Severity of Acute on Chronic Kidney Disease?

Abstract

Abstract BACKGROUND AND AIMS Reaching a SCr ≥ 4 is one criterion of classification for stage 3 in the KDIGO-2012 AKI guidelines. No previous study has challenged this arbitrary cut point by comparing its performance on how patients with pure AKI (pAKI) versus acute on chronic kidney disease (AoCKD) reach that ‘magical number’, and how it affects the prognosis. METHOD Retrospective study of patients with AKI, classified according to the KDIGO-2012 guidelines. We analysed a sub-group of patients that reached a maximum SCr ≥ 4 and divided them in pAKI (basal eGFR ≥ 60) and AoCKD (≥15–≤59). We evaluated epidemiological and clinical variables, and compared the clinical outcomes needed for HD, in-hospital mortality and HD dependence at discharge. As 21 (6%) of AoCKD individuals already had a basal SCr ≥ 4.0, they were excluded in the analysis. RESULTS A total of 492 individuals met the inclusion criteria: 341 (69%) in the AoCKD group. Individuals in this group were older and had a higher Charlson's index. Table 1A summarizes the comparison of clinical characteristics, all patients in the pAKI group reached a four SCr with a rate of SCr increments ≥ 3×. We found no statistically significant difference in in-hospital mortality and the need for HD. The AoCKD group was more dependent on HD at discharge (Table 1B). Figure 1 shows the rate of SCr increments by which individuals reached > 4.0 mg/dL. CONCLUSION We found that individuals in the AoCKD group differ in their basal characteristics from the pAKI group and need lesser increments in SCr to reach the magical number of 4.0 mg/dL to be classified in stage 3. May be, one size does not fit all, and individuals with prior CKD may benefit from a lower rate of SCr increase to stratify AKI severity. We consider that a pitfall in this staging criterion consists in the small portion of patients in the AoCKD group that have a basal SCr ≥ 4.0, with a skew to AKI-KDIGO stage 3.