Relationship between lactate-albumin ratio and all-cause mortality in chronic kidney disease without continuous renal replacement therapy in the intensive care unit ward: a retrospective analysis of the MIMIC-IV database

The relationship between the lactate-albumin ratio (LAR) and all-cause mortality in chronic kidney disease (CKD) has not been previously reported. Considering that continuous renal replacement therapy (CRRT) in patients with CKD can influence changes in LAR ratio, this study aimed to explore the relationship between LAR levels and all-cause mortality in patients with CKD without CRRT in intensive care unit (ICU) and assessed the association between LAR and outcome. For patients with CKD with no CRRT application in the medical information mart for intensive care IV (MIMIC-IV) database and admitted to the ICU ward, the first test results within 24 h of the ICU admission were extracted, and patients were selected based on exclusion criteria. The primary endpoint was all-cause mortality rates at 30 days, 90 days, and 365 days. Cox proportional hazard models and restricted cubic splines (RCS) were used to study the relationship between LAR and mortality rates at 30 days, 90 days, and 365 days. Kaplan–Meier curves were used to estimate survival probabilities across different levels of LAR ratio, and subgroup analysis with interaction tests was conducted to evaluate the robustness of the findings. After applying the inclusion and exclusion criteria, 987 patients were included in this study. In the univariate and multivariate Cox analysis, the LAR was statistically significant. Concurrently, based on the CKD stage (Kidney Disease Improving Global Outcomes 2012 CKD guideline), it was divided into CKD 1–2, CKD 3–4, and CKD 5, named early, middle, and late stages. Among them, the mortality rate of the middle stage was the most significant. The 30-day, 90-day, and 365-day mortality rates among patients with CKD with no CRRT were 38.9%, 41.6%, and 41.8%, respectively. Analyzing LAR as a continuous variable, we revealed an increase in 30-day, 90-day, and 365-day mortality rates of 30% (hazard ratio [HR] = 1.30, 95% confidence intervals [CI]: 1.18–1.43, P < 0.001), 32% (HR = 1.32, 95% CI: 1.20–1.45, P < 0.001), and 32% (HR = 1.32, 95% CI: 1.21–1.45, P < 0.001) in Model III, respectively. RCS indicated a positive, nonlinear correlation between LAR ratio and mortality rates at 30 days, 90 days, and 365 days. LAR is a significant and independent predictor of mortality in ICU patients with CKD not receiving CRRT. After multivariable adjustment, each unit increase in LAR was associated with an approximately 30% increase in 30-day mortality risk (HR 1.30, 95% CI 1.18–1.43, p < 0.001), highlighting its potential as a potent prognostic marker.