Lactate-to-albumin ratio index correlates with the occurrence and prognosis of acute kidney injury complicated by cardiac surgery

Background The lactate-to-albumin ratio (LAR), an emerging biomarker, has been recognized as an indicator of poor prognosis in various critical illnesses. However, the relationship between LAR and the incidence and prognosis of cardiac surgery-associated acute kidney injury (AKI) remains uncertain. This study aims to elucidate this relationship through a comprehensive analysis of a large cohort from the MIMIC database. Methods This study utilized a retrospective cohort design to analyze adult patients admitted to the intensive care unit (ICU) following cardiac surgery. Statistical methods such as logistic regression, restricted cubic spline (RCS) analysis, and subgroup analysis were employed to assess the predictive value of LAR for the occurrence of AKI and adverse outcomes after cardiac surgery. Results A total of 11,624 cardiac surgery patients were included, among which 5,965 developed acute kidney injury. The LAR index was significantly higher in the cardiac surgery population that developed AKI compared to those who did not. Logistic regression analysis indicated that LAR was significantly associated with in-hospital and ICU mortality, even after adjusting for potential confounders across multiple models. RCS analysis revealed a non-linear relationship between elevated LAR and increased risks of in-hospital and ICU mortality in patients with AKI following cardiac surgery. Correlation analyses demonstrated a significant association between LAR and length of stay in the hospital (LOS-H), length of stay in the ICU (LOS-ICU), and SOFA scores. ROC curve analysis indicated that the LAR index had good predictive value for mortality in the AKI population following cardiac surgery. Subgroup analyses consistently showed that elevated LAR was associated with increased risks of in-hospital and ICU mortality in older adults, females, and populations regardless of hypertension, chronic kidney disease, diabetes, or chronic heart failure. Conclusions Elevated LAR is associated with the incidence of cardiac surgery-associated acute kidney injury and the higher mortality risk in this population. Our findings highlight the previously unrecognized role of LAR in predicting mortality in patients with AKI following cardiac surgery, warranting further validation.