SERUM LACTATE: A COMORBIDITY-INDEPENDENT PREDICTOR OF MORTALITY IN EMERGENCY DEPARTMENTS

Abstract

Predicting clinical deterioration in the Emergency Department (ED) remains a diagnostic challenge. While serum lactate is a well-established marker for tissue hypoperfusion in sepsis, its utility as a prognostic marker independent of a patient's chronic health status requires further validation in undifferentiated acute presentations.

Aim: The study aimed to evaluate the role of serum lactate as an independent predictor of 30-day mortality in ED patients presenting with dyspnea, altered sensorium, and fever.

Methods: A prospective observational study was conducted on 64 patients at KVG Medical Hospital between June 2024 and March 2025. Patients were stratified into four risk groups based on admission serum lactate levels: Normal (<2.0 mmol/L), Mild (2.0–4.0 mmol/L), High (>4.0 mmol/L), and Critical (>8.0 mmol/L). Clinical outcomes were analyzed against demographic profiles and comorbidity status (including diabetes and hypertension) using Fisher’s exact test.

Results: A statistically significant association was observed between elevated serum lactate and mortality ($p < 0.0001$). Patients in the High and Critical risk groups demonstrated a mortality rate of 95.45%. Notably, 50% of mortality cases occurred in patients with no prior comorbidities. Lactate levels $>6$ mmol/L were identified as a critical threshold significantly associated with death, regardless of the patient's age or underlying chronic disease burden.

Conclusion: Serum lactate serves as a robust, comorbidity-independent predictor of mortality in the ED. Elevated levels warrant immediate aggressive intervention, as they signal a high risk of premature death even in previously healthy individuals.