Association Between Serum Lactate Levels and Mortality in Acute Poisoning Cases: A Prospective Observational Study

Abstract

Background: Acute poisoning represents a significant global health concern with substantial morbidity and mortality. Early prognostication is crucial for appropriate resource allocation and aggressive management. Serum lactate, a marker of tissue hypoperfusion and hypoxia has shown promise as a predictor of outcomes in various critical illnesses. This study aimed to evaluate the association between serum lactate levels and mortality in patients with acute poisoning.

Methodology: A prospective observational study was conducted on 324 patients with acute poisoning admitted to the emergency department of a tertiary care hospital between January 2024 and December 2024. Serum lactate levels were measured at admission and 6 hours post-admission. Demographic data, poisoning characteristics, clinical parameters, and outcome measures were recorded. Receiver operating characteristic (ROC) curve analysis was performed to determine optimal lactate cutoff values for predicting mortality. Multivariate logistic regression was used to identify independent predictors of mortality.

Results: The overall mortality rate was 12.3% (40/324). The mean initial serum lactate level was significantly higher in non-survivors compared to survivors (7.9 ± 3.2 mmol/L vs. 2.8 ± 1.9 mmol/L, p<0.001). Lactate clearance at 6 hours was significantly lower in non-survivors (15.3 ± 8.7% vs. 38.6 ± 15.2%, p<0.001). ROC curve analysis yielded an area under curve (AUC) of 0.86 (95% CI: 0.79-0.93) for initial lactate levels, with an optimal cutoff value of 4.5 mmol/L (sensitivity 84.6%, specificity 79.3%). Multivariate analysis identified initial serum lactate ≥4.5 mmol/L (OR 5.87, 95% CI: 2.31-14.92, p<0.001) and lactate clearance <20% at 6 hours (OR 4.23, 95% CI: 1.82-9.84, p=0.001) as independent predictors of mortality, after adjusting for age, toxin type, time to presentation, and Glasgow Coma Scale score.

Conclusion: Elevated serum lactate levels at admission and poor lactate clearance at 6 hours are significantly associated with increased mortality in acute poisoning cases. Serum lactate could serve as a valuable prognostic biomarker for risk stratification and early intervention in poisoning management.