The Usefulness of Base Deficit (BD) as a Predictor of Severity in Organophosphorus (OP) Poisoning: A Retrospective Single-center Observational Study

Objective: Organophosphates are chemical agents that originate from derivatives of phosphoric, phosphonic, or phosphinic acid compounds. They are one of the leading causes of death by intentional self-harm worldwide. The objective of the study is to evaluate the utility of Base Deficit as a prognostic indicator of OP poisoning and assess its predictive accuracy for in-hospital mortality. Methodology: This retrospective single-center observational study analyzed data from adult patients who presented to the emergency department with the history of organophosphorus compound ingestion over a 2-year 6-month period. Relevant clinical history, physical examination details, and biochemical investigations were collected from electronic medical records and entered into appropriate sections on a pre-designed proforma. Patients with a history of co-ingestion of other compounds or carbamates, chronic kidney disease, pre-hospital cardiac arrest, or those discharged against medical advice were excluded. Results: Data from 122 patients were analyzed. They were stratified into quartiles based on their base deficit values. The most common OP compound ingested was found to be Chlorpyrifos (n=41, 33.6%). The average duration of hospital stay documented in this study was 16 days, and the in-hospital case fatality rate was 15.38%. In univariate logistic regression, both base deficit (BD) and APACHE II scores were significantly associated with in-hospital mortality. Receiver Operating Characteristic (ROC) analysis showed that when BD was more than 6.42, it predicted mortality with a 73.7% sensitivity and 70.9% specificity, and when APACHE II scores were above 14.5, sensitivity was 73.7% and specificity was 75.7%. Used in conjunction, these markers enhanced predictive accuracy. Further, multivariate regression analysis confirmed base deficit as an independent predictor of in-hospital mortality (aOR 1.25, p = 0.031). A combined model of base deficit and APACHE II score showed improved predictive performance (AUC = 0.86), supporting their use in early clinical risk stratification. Conclusion: Our study shows that base deficit is a valuable and accessible marker for early risk stratification in OP poisoning. Particularly when combined with APACHE II scoring, it can guide timely clinical decisions and resource allocation, especially in resource-limited settings.