Prognostic significance of lactate/albumin ratio in respiratory failure and sepsis

Abstract

Introduction: Prognostic markers like SOFA and APACHE-II scores for sepsis and acute respiratory failure (ARF) are often complex for routine use. This study evaluated the lactate-albumin ratio (LAR) as a prognostic marker for in-hospital outcomes, mechanical ventilation, and inotrope requirement.

Methods: A prospective cohort study was conducted among ICU and Internal Medicine Unit patients at Manipal Teaching Hospital, approved by the Institutional Review Committee (approval number IRC/MCOMS/584). Arterial samples for ABG values (lactate, PaO2, PaCO2, HCO3, and FiO2) and venous samples for albumin, bilirubin and creatinine were collected on admission. Arterial lactate, serum albumin, LAR and SOFA scores were recorded and compared with in-hospital outcomes. Statistical analyses were performed using SPSS version 25, with ROC-AUC for assessing prognostic markers (LAR, lactate alone) and Delong's test for comparison.

Result: Among 115 sepsis cases, ROC-AUC of LAR for in-hospital mortality (cut-off 1.78), mechanical ventilation (1.28), and inotropes (1.07) were 0.914, 0.881, and 0.819, respectively. Among 99 ARF cases, ROC-AUC for mortality (1.98), ventilation (1.10), and inotropes (1.18) were 0.878, 0.958, and 0.876. Among 43 sepsis + ARF cases, ROC-AUC for mortality (2.14), ventilation (1.20), and inotropes (1.20) were 0.853, 0.874, and 0.849.

Conclusion: The lactate-albumin ratio was a better prognostic marker than albumin alone and SOFA score for predicting in-hospital mortality, need for mechanical ventilation and inotropes in sepsis, ARF and combined Sepsis and ARF patients whereas it was statistically equivalent to lactate alone in predicting in hospital outcome. Lactate-albumin ratio also indicated disease progression, where an increase in cut-off value was seen with progressed or severe disease.

Keywords: ARF; LAR; Lactate; albumin; hospital-outcome; mortality; predictor; sepsis.

Figure 1.

ROC – AUC curve for lactate albumin ratio, lactate alone, albumin alone and SOFA score for (a) mortality in sepsis; (b) need for mechanical ventilation in sepsis; (c) need for inotropes in sepsis; (d) mortality in ARF; (e) need for mechanical ventilation in ARF; (f) need for inotropes in ARF. (note: ROC-AUC of albumin is negatively associated with each of the hospital outcome). The values of AUC of each variable are mentioned in detail in Table 2 for ROC-AUC curve of (a), (b) and (c) for cases of sepsis where as in Table 3 for ROC-AUC curve of 1(e), 1(f) and 1(g) for cases of ARF.

Figure 2.

ROC-AUC curve for LAR, lactate alone, SOFA score, albumin alone in patient diagnosed with both sepsis and ARF cases for (a) mortality, (b) need of mechanical ventilation, (c) need of inotropes. (note: ROC-AUC of albumin is negatively associated with each of the hospital outcome). The values of AUC of each variable are mentioned in detail in Table 4.

Figure 3.

Progression of disease severity as per increasing cut-off value of LAR in (a) sepsis, (b) ARF, (c) both sepsis and ARF. The arrows in this figure demonstrate decreasing trend of cut off value of LAR as the disease severity decreases.