Characteristics for renal recovery after acute kidney injury in cohorts of elderly and non elderly: a multicenter retrospective cohort study

Background: Failure to recover renal function after acute kidney injury (AKI) is associated with an increase in long-term mortality. The characteristics of renal recovery in elderly and nonelderly cohorts are not clear. The purpose of this study was to explore the risk factors for renal nonrecovery among elderly and nonelderly patients with acute kidney injury (AKI). Methods: : A multicenter retrospective cohort of 583 critically ill patients with AKI was examined. All patients were divided into two cohorts, age < 63 and age ≥ 63 years old; on the basis of renal recovery at 30 days after AKI, the two patient cohorts were further divided into a renal recovery group and a renal nonrecovery group. Multivariate logistic regression was used to analyze the risk factors affecting renal recovery in the two cohorts. Results: : The 30-day renal recovery rate of patients aged < 63 years was 67.5% (191/283), multivariate analysis showed that the independent risk factors affecting renal nonrecovery in age < 63 years old included AKI stage, blood lactate level and hemoglobin level, the AUC for predicting renal nonrecovery was 0.876 (95% CI, 0.835-0.917). The 30-day renal recovery rate of patients aged ≥ 63 years was 32.3% (97/300), multivariate analysis showed that the independent risk factors for renal nonrecovery in age ≥ 63 years old included diabetes mellitus, surgery with general anesthesia, AKI stage, APACHE II score and hemoglobin level. The AUC for predicting renal nonrecovery was 0.863 (95% CI, 0.816-0.909). Conclusions: : The renal nonrecovery after AKI in patients aged ≥ 63 years was more strongly affected by multiple risk factors, such as diabetes mellitus, surgery with general anesthesia and APACHE II score, in addition to hemoglobin and AKI stage.