An exploratory study of ascitic fluid lactate as prognostic factor of mortality in cirrhotic patients with spontaneous bacterial peritonitis

Abstract

Background: The diagnostic value of ascitic fluid lactate (AF lactate) was previously evaluated in spontaneous bacterial peritonitis (SBP) but its prognostic value was not established.

Aim: To assess the prognostic value of AF lactate in SBP.

Methods: We prospectively studied 63 consecutive patients with SBP. Fifty patients with acute-on-chronic liver failure (ACLF) or acute decompensation (AD) (ACLF/AD group) without SBP and 30 with stable decompensated cirrhosis (DC) were included as controls. In SBP, mortality was recorded at 30, 90 and 180 days.

Results: Arterial and AF lactate were significantly higher in SBP compared to other groups. Analyzing the SBP group alone, AF lactate accurately differentiated survivors from nonsurvivors in all time points. The prognostic performance of AF lactate was improved over time, with the area under the receiver operating characteristic computed at 0.894, 0.927 and 0.934 at 30, 90 and 180 days, respectively. The cutoff level of 2 mmol/L was associated with 100, 100 and 94.7% sensitivity, 57.9, 73.3 and 80% specificity, 61, 80.5 and 87.8% positive predictive value and 100, 100 and 90.9% negative predictive value, respectively. Arterial lactate, neutrophil-to-lymphocyte ratio (NLR) and Model for End-Stage Liver Disease (MELD) score predicted outcomes less accurately than AF lactate. Patients with AF lactate >2 mmol/L had a worse prognosis compared to patients with ≤2 mmol/L (log-rank P < 0.001). No case with AF lactate ≤2 mmol/L died within 90 days postSBP diagnosis. In Cox multivariate analysis at all time points, only AF lactate and NLR were independent predictors of mortality.

Conclusion: An AF lactate level of 2 mmol/L has a high ability to differentiate survivors from nonsurvivors in the first 180 days postSBP. Its prognostic value outperformed arterial-lactate, NLR and MELD.