To understand the recovery rate of renal function, clinical features, and risk factors in elderly patients with sepsis-associated acute kidney injury (SA-AKI).

A retrospective analysis was made of the clinical data of SA-AKI patients who were no less than 75 years old from the Chinese PLA General Hospital, National Clinical Research Center for Geriatric Diseases, from January 2018 to December 2019. According to recovery of serum creatinine (Scr) at discharge, the patients were divided into recovery group (Scr≤125% baseline value at discharge), and non-recovery group (Scr>125% baseline value at discharge). AKI was defned according to the 2012 Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Persistent AKI was defined as no decrease of Scr (>baseline value) at 48 hours after the occurrence of AKI.

The 192 patients had a median age of 87 (84-90) years, and included 183 males (95.3%). At the time of discharge, the renal function was recovered in 78.1% (150/192) patients, and not recovered in 21.9%(42/192) patients. There were statistically significant differences between the recovery group and the non-recovery group in gender ratio (P<0.05), baseline Scr (P<0.01), and baseline eGFR (P<0.001). Compared with the recovery group, the non-recovery group showed higher Scr at diagnosis of AKI (P<0.05), higher peak Scr (P<0.001), higher rate of renal replacement therapy (P<0.05), higher rate of mechanical ventilation (P<0.001), and a higher proportion of persistent AKI (P<0.001). Multivariate logistic regression analysis revealed that there were statistically significant differences between the recovery group and the non-recovery group in baseline eGFR (70-79: OR=0.258, 95%CI: 0.088-0.757, P<0.05; 80-89: OR=0.132, 95%CI: 0.041-0.421, P=0.001; ≥90: OR=0.096, 95%CI: 0.015-0.627, P=0.014), in mechanical ventilation (OR=6.715, 95%CI: 2.665-16.918, P<0.001), and in persistent AKI (OR=6.706, 95%CI: 2.741-16.404, P<0.001).

The recovery rate of renal function in elderly patients with SA-AKI was 78%. The increased eGFR was a protective factor while mechanical ventilation and persistent AKI were risk factors for the recovery of the renal function.