We investigate the clinical utility of the lactate/albumin (L/A) ratio as an early prognostic marker of ICU mortality in a large cohort of unselected critically ill patients.
A retrospective single-center study using data from the Multiparameter Intelligent Monitoring Intensive Care III (MIMIC-III) database collected between 2001 and 2012. We screened adult patients (age ≥ 15) with measured lactate and albumin on the first day of ICU stay to evaluate the prognostic performance of the lactate and lactate/albumin (L/A) ratio for ICU mortality prediction.
The overall ICU mortality in the 6414 eligible ICU patients was 16.4%. L/A showed a receiver-operating characteristics area under the curve (ROC-AUC) value of 0.69 (95% CI: 0.67, 0.70) to predict ICU mortality, higher than lactate 0.67 (95%CI: 0.65, 0.69). Regardless of the lactate level, L/A yielded better ROC-AUC compared to the lactate level [normal lactate (<2.0 mmol/L): 0.63 vs 0.60; intermediate lactate (2.0 mmol/L ≤ lactate <4.0 mmol/L): 0.58 vs 0.56; high lactate (≥4.0 mmol/L): 0.67 vs 0.66]. L/A was a better prognostic marker for ICU mortality in patients with decreased lactate elimination [hepatic dysfunction: 0.72 vs 0.70; renal dysfunction 0.70 vs 0.68]. The L/A ratio ROC-AUC was better in patients with sepsis (0.68 vs 0.66) and those who developed severe sepsis or septic shock (0.68 vs 0.66).
The performance of L/A and lactate were equivalent in predicting ICU mortality and can be used as early prognostic markers for ICU patients with different initial lactate level and the presence of hepatic or renal dysfunction.

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