Predictors of ethylene glycol ingestion cases called into a regional poison center

Poison center consultations for potential toxic alcohol poisonings are challenging because blood levels are typically not immediately available. The primary objective of this study was to determine whether readily obtainable laboratory values can be used to accurately and rapidly diagnose these poisonings. Over a 15-month period, patients with a history of toxic alcohol ingestion or a metabolic acidemia (pH ≤ 7.30 or serum bicarbonate ≤ 18 mEq/L) that prompted a poison center consultation were enrolled. A predictive logistic regression model was used to assess the combined ability of serum pH, calcium, osmolar gap, and anion gap levels to predict a final diagnosis of toxic alcohol poisoning. There were 102 subjects included in the analysis. A total of 44% (45/102) patients had a final diagnosis of ethylene glycol (EG) poisoning. Higher levels of calcium, osmolar gap, and anion gap were independently associated with statistically significant or marginally significant increases in the odds of a final diagnosis of EG poisoning. The c-index was estimated at 0.81, indicating that the model showed a reasonable ability to discriminate EG cases from others. The final model had a sensitivity and specificity of 78% and 89%, respectively, and positive and negative predictive values of 84% and 83% respectively. The combination of elevated calcium, osmolar gap, and anion gap is associated with a high likelihood of EG poisoning, but clinician gestalt is still essential for its diagnosis. Further refinement of the model is needed.