Association of the Lactate/Albumin Ratio with Mortality and Hypovolemia in Critically Ill Patients: A Retrospective Cohort Study

<b>Background/Objectives:</b> Previous research has demonstrated that the lactate/albumin ratio (L/A) may predict mortality among critically ill patients. Based on pathophysiological rationale, L/A may also correlate with volume status, however such an association has not been investigated extensively. This retrospective cohort study aimed to confirm the prognostic value of L/A and to assess the prognostic value of L/A and its relationship with hypovolemia severity in intensive care unit (ICU) patients. <b>Methods</b>: We analyzed data from consecutive adult patients admitted to the ICU. Admission L/A was evaluated in relation to 30-day mortality and indirect markers of volume status (mean arterial pressure on admission, median dose of norepinephrine and fluid intake within the first 24 h of ICU stay). <b>Results</b>: A total of 1421 patients were included. L/A ≥ 0.06 (estimated on the basis of ROC curve using the Youden index) was an independent predictor of 30-day mortality (HR = 1.423; 95%CI 1.183-1.712; <i>p</i> < 0.001). L/A moderately correlated with markers of absolute or relative hypovolemia, i.e., lower mean arterial pressure (r = -0.353, <i>p</i> < 0.001) on admission, higher norepinephrine dose (r = 0.506, <i>p</i> < 0.001) and greater fluid intake (r = 0.233, <i>p</i> < 0.001) within the first 24 h of ICU stay. Furthermore, L/A ≥ 0.06 on admission was an independent risk factor for the implementation of continuous renal replacement therapy (OR = 2.134; 95%CI 1.652-2.757; <i>p</i> = 0.001). <b>Conclusions</b>: L/A is not only a predictor of poor prognosis but also may be a valuable indirect marker of the extent of hypovolemia in critically ill patients. Further prospective studies are necessary to assess if this parameter should incline a decision for more aggressive fluid management in hypovolemic patients.