Association Between Lactate-to-Albumin Ratio and 28-Day All-Cause Mortality in Critical Care Patients with COPD: Can Both Arterial and Peripheral Venous Lactate Serve as Predictors?

Abstract

Background: Lactate-to-albumin ratio (LAR) has been reported as a useful predictor for multiple critical illnesses. However, the association between LAR and mortality in patients with chronic obstructive pulmonary disease (COPD) remains unclear. This study aims to clarify the correlation between LAR and 28-day all-cause mortality in patients with COPD and to investigate whether LAR calculated using arterial lactate (AL) or peripheral venous lactate (PVL) can serve as predictive indicators.

Methods: A total of 1428 patients from the Medical Information Mart for Intensive Care (MIMIC) IV database (version 2.2) and 2467 patients from the eICU Collaborative Research Database (eICU-CRD, version 2.0) were included in this study. Propensity score matching (PSM) method was conducted to control confounders. Cox proportional hazards model, Kaplan-Meier survival method, subgroup analysis and receiver operating characteristic (ROC) analysis were performed to assess the predictive ability of LAR. To verify our hypothesis, data from the two databases were analyzed individually.

Results: After adjusting for covariates, LAR calculated using either AL (MIMIC IV, HR = 1.254, 95% CI, 1.013-1.552, P = 0.038) or PVL (eICU-CRD, HR = 1.442, 95% CI, 1.272-1.634, P < 0.001) was independently associated with 28-day all-cause mortality in COPD patients. Kaplan-Meier analysis showed that patients with higher LAR value had significantly higher all-cause mortality (all P < 0.05). This association was consistent across subgroup analyses. In addition, the ROC analysis suggested that LAR calculated using PVL may have better predictive performance compared to using AL.

Conclusion: LAR calculated using both AL and PVL can independently predict the 28-day all-cause mortality after ICU admission in patients with COPD and higher level of LAR is related to higher mortality risk.

Keywords: 28-day; all-cause mortality; chronic obstructive pulmonary disease; cohort; lactate-to-albumin ratio; prognosis factors.

Figure 1

(A) Cut-off value of LAR for 28-day mortality in patients with COPD calculated using X-tile in MIMIC. (B) Cut-off value of LAR for 28-day mortality in patients with COPD calculated using X-tile in eICU.

Figure 2

(A) Standardized mean differences (SMD) between the original and matched cohorts in MIMIC. (B) Standardized mean differences (SMD) between the original and matched cohorts in eICU.

Figure 3

(A) Kaplan Meier curve of high and low LAR (calculated using arterial lactate) groups (MIMIC, before PSM, log-rank P < 0.001). (B) Kaplan Meier curve of high and low LAR (calculated using arterial lactate) groups (MIMIC, after PSM, log-rank P = 0.028). (C) Kaplan Meier curve of high and low LAR (calculated using peripheral venous lactate) groups (eICU, before PSM, log-rank P < 0.001). (D) Kaplan Meier curve of high and low LAR (calculated using peripheral venous lactate) groups (eICU, after PSM, log-rank P < 0.001).

Figure 4

Forest plot for the subgroup analysis of the association between 28-d mortality and LAR (calculated using arterial lactate) using the MIMIC IV database.

Figure 5

Forest plot for the subgroup analysis of the association between 28-d mortality and LAR (calculated using peripheral venous lactate) using the eICU-CRD database.