Lactate-To-Albumin Ratio and Mortality in Critically Ill Patients with Pneumonia: Insights From the MIMIC-IV Database
Thanh Luan Nguyen, Cong Dang Tran, Phan Ngoc An Huynh, Trang Nguyen Hoai Dinh, Ngoc Nhu Y Nguyen, Van Hoang Nam Ho, Hoang Ngoc Thao DuongObjectives
To evaluate the association of the lactate-to-albumin ratio (LAR) with short- and long-term mortality in critically ill patients with pneumonia.
Methods
We conducted a retrospective cohort study using the Medical Information Mart for Intensive Care IV (MIMIC-IV, version 3.1) database, including adult patients with pneumonia admitted to the intensive care unit (ICU). LAR was calculated using lactate and albumin measurements obtained around ICU admission and categorized into tertiles. The primary outcome was 60-day mortality, and the secondary outcome was 180-day mortality. Restricted cubic spline analysis, multivariable Cox regression, and receiver operating characteristic curve analysis were performed to evaluate the association between LAR and mortality. The incremental prognostic value of LAR added to the SOFA score was assessed using discrimination and reclassification measures.
Results
A total of 5,610 patients were included and stratified into tertiles of LAR after restricted cubic spline analysis demonstrated a nonlinear association between LAR and mortality (P for nonlinearity <0.001 for both outcomes). Mortality increased progressively across LAR tertiles. For 60-day mortality, rates were 26.3% in T1, 34.9% in T2, and 48.1% in T3. For 180-day mortality, corresponding rates were 33.6%, 42.9%, and 54.4%, respectively (all p<0.001). In multivariable Cox proportional hazards models, higher LAR tertiles were associated with increased mortality, with hazard ratios (HRs) for 60-day mortality of 1.20 (95% confidence interval [CI], 1.06–1.35) for T2 and 1.54 (95% CI, 1.37–1.73) for T3, compared with T1. Similar associations were observed for 180-day mortality, with HRs of 1.20 (95% CI, 1.08–1.33) and 1.50 (95% CI, 1.34–1.67), respectively. LAR demonstrated better discriminative performance than lactate and comparable performance to albumin. Adding LAR to SOFA increased the area under the curve from 0.660 to 0.687 (absolute change, 0.027; 95% CI, 0.019–0.036), with a continuous net reclassification improvement of 0.245 (95% CI, 0.194–0.296).
Conclusions
Higher LAR was associated with increased short-term and long-term mortality in critically ill patients with pneumonia. Prospective multicenter studies are needed to validate the prognostic value and clinical utility of LAR.