Association between lactate/albumin ratio and prognosis in critically ill patients with acute kidney injury undergoing continuous renal replacement therapy

Abstract

Background: The primary objective was to examine the association between the lactate/albumin ratio (LAR) and the prognosis of patients with acute kidney injury (AKI) undergoing continuous renal replacement therapy (CRRT).

Methods: Utilizing the Medical Information Mart for Intensive Care IV (MIMIC-IV, v2.0) database, we categorized 703 adult AKI patients undergoing CRRT into survival and non-survival groups based on 28-day mortality. Patients were further grouped by LAR tertiles: low (< 0.692), moderate (0.692-1.641), and high (> 1.641). Restricted cubic splines (RCS), Least Absolute Shrinkage and Selection Operator (LASSO) regression, inverse probability treatment weighting (IPTW), and Kaplan-Meier curves were employed.

Results: In our study, the patients had a mortality rate of 50.07% within 28 days and 62.87% within 360 days. RCS analysis revealed a non-linear correlation between LAR and the risk of mortality at both 28 and 360 days. Cox regression analysis, which was adjusted for nine variables identified by LASSO, confirmed that a high LAR (>1.641) served as an independent predictor of mortality at these specific time points (p < 0.05) in AKI patients who were receiving CRRT. These findings remained consistent even after IPTW adjustment, thereby ensuring a reliable and robust outcome. Kaplan-Meier survival curves exhibited a gradual decline in cumulative survival rates at both 28 and 360 days as the LAR values increased (log-rank test, χ2 = 48.630, p < 0.001; χ2 = 33.530, p < 0.001).

Conclusion: A high LAR (>1.641) was found to be an autonomous predictor of mortality at both 28 and 360 days in critically ill patients with AKI undergoing CRRT.

Keywords: Lactate/albumin ratio; MIMIC-IV database; acute kidney injury; continuous renal replacement therapy; prognosis.

Figure 1.

The flowchart showing the systematic process for selecting study participants.

Figure 2.

RCS Analyses of the correlation between lactate/albumin ratio (LAR) and the risk of 28-day (a) and 360-day (b) all-cause mortality in patients with acute kidney injury (AKI) undergoing continuous renal replacement therapy (CRRT).

Figure 3.

Clinical features were selected using LASSO regression with cross-validation. (a) The selection results for the optimal parameter λ (cross-validation). Two dotted lines represent two specific λ values: lambda.min (left) and lambda.lse (right). (b) The dynamic process chart of feature selection through LASSO regression. Each curve represents the trajectory of a single independent variable coefficient, with the vertical axis showing the value of the coefficient for the independent variable, the lower horizontal axis indicating log (λ), and the upper horizontal axis indicating the number of variables with non-zero coefficients present in the model at that time.

Figure 4.

Kaplan-Meier Survival curves for the cumulative survival rates at 28-day (a) and 360-day (b) across different levels of lactate/albumin ratio (LAR).

Figure 5.

Kaplan-Meier Survival curves for the cumulative survival rates at 28-day (a) and 360-day (b) after IPTW across different levels of lactate/albumin ratio (LAR).