Evaluating the use of APACHE II Score in Acute Organophosphorus Poisoning: A Prospective and Retrospective Observational Study

Background: Organophosphorus compounds (OPCs) are widely used pesticides and a major cause of poisoning-related mortality in India. Severe toxicity results from acetylcholinesterase inhibition leading to cholinergic crisis. Reliable prognostic markers are essential for early risk stratification. The Acute Physiology and Chronic Health Evaluation II (APACHE II) score is extensively used in ICUs, but its utility in OPC poisoning remains incompletely defined. Aim: To evaluate the predictive accuracy of the APACHE II score in assessing severity and clinical outcomes of organophosphorus poisoning. Methods: A prospective and retrospective observational study was conducted in the Department of Medicine, Jorhat Medical College & Hospital, including 75 adults with confirmed OPC poisoning. Clinical parameters, laboratory variables, and APACHE II score calculated within 24 hours of ICU admission were analyzed. Outcomes were compared between survivors and non-survivors. Results: Of 75 patients, 52% survived and 48% died. Most were males (64%) and 18–30 years old. Triazophos (26.7%) and acephate (20%) were the most frequent agents. Significant predictors of mortality included elevated temperature (p=0.010), lower GCS (p=0.048), high respiratory rate (p=0.005), metabolic acidosis (pH; p=0.019), elevated creatinine (p=0.033), hyponatremia (p=0.011), and higher APACHE II score (p=0.009). No significant association was noted with age, MAP, heart rate, hematocrit, or time to admission. Conclusion: APACHE II is a reliable prognostic tool in organophosphorus poisoning, correlating significantly with mortality risk. Temperature dysregulation, respiratory distress, acidosis, and electrolyte abnormalities emerged as key clinical predictors. Early scoring may facilitate timely triage and targeted interventions.