Accuracy of an Enzymatic Assay Device for Sermn Ethanol Measurement

Abstract

Objective: To determine the accuracy of an enzymatic assay of serum to measure blood ethanol levels in the emergency department. Methods: A blinded, prospective study of emergency department patients for whom a blood ethanol was ordered and performed. After skin prep with betadine, two blood samples were drawn into separate sodium fluoride-containing vacutainers. One sample was sent to the hospital laboratory for blood ethanol analysis. The other was centrifuged for 5 minutes and the serum was then assayed using the QED A350′ Saliva Alcohol Test. Values were then compared by kappa statistic and Pearson's correlation. Sensitivity and specificity calculations were determined for the QED device to detect a blood ethanol > 100 mg/dL. Results: Sixty-six patients were enrolled. The kappa value for QED compared to lab blood ethanol was 0.93. The Pearson's correlation coefficient was 0.94. The QED, in general, tended to overestimate blood ethanol slightly. The QED was 100% sensitive and 82% specific in detecting a blood ethanol > 100 mg/dL. Conclusions: Analysis of serum using a QED A350′ is a sensitive and accurate index of low to moderate increases in blood ethanol appropriate to emergency department, but not legal, interpretation.