Prognostic Value of the Lactate-to-Albumin and C-Reactive Protein-to-Albumin Ratios in COVID-19–Associated ARDS

Background: Coronavirus disease 2019 (COVID-19) is frequently complicated by acute respiratory distress syndrome (ARDS), which is associated with high mortality. The lactate-to-albumin ratio (LAR) and C-reactive protein-to-albumin ratio (CAR) have been proposed as prognostic markers in critical illness, but their comparative performance in COVID-19–associated ARDS is not well established. Methods: We conducted a retrospective cohort study using the MIMIC-IV database, which contains data from Beth Israel Deaconess Medical Center, United States, including COVID-19 ICU admissions from 2020 to 2022. Adult COVID-19 patients with available PaO2/FiO2, lactate, albumin, and C-reactive protein measurements within the first 48 h of ICU admission were included. Receiver operating characteristic analysis, Kaplan–Meier survival analysis, and Cox proportional hazards regression were performed. Results: Of the 3620 patients screened, 66 met the inclusion criteria; 36 survived and 30 died. Non-survivors had significantly higher LAR and CAR values at ICU admission. In ROC analyses, LAR demonstrated moderate discrimination for 30-day mortality (AUC 0.706) and showed higher discriminatory performance than CAR in most subgroup analyses. Among ARDS patients, LAR showed moderate predictive ability (AUC 0.693), compared with CAR (AUC 0.655). In severe ARDS, both markers demonstrated improved discrimination (0.722 AUC for LAR and 0.797 for CAR). High LAR was associated with significantly higher 30-day mortality in all ARDS patients (60.5% vs. 24.0%; p = 0.0056) and severe ARDS patients (72.0% vs. 20.0%; p = 0.0022). Elevated CAR was also associated with increased mortality, particularly in severe ARDS (73.1% vs. 14.3%; p < 0.001). In multivariable Cox regression, LAR remained independently associated with 30-day mortality. Conclusions: LAR demonstrated independent prognostic value for 30-day mortality in critically ill COVID-19 patients with ARDS. CAR showed variable performance. These readily available biomarkers, particularly LAR, may aid early risk stratification although larger studies are needed to confirm these findings.