Accuracy of an enzymatic assay device for serum ethanol measurement

Objective: To determine the accuracy of an enzymatic assay of serum to meas ure blood ethanol levels in the emergency department. Methods: A blinded, p rospective 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 sampl e 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 an d Pearson's correlation. Sensitivity and specificity calculations were dete rmined for the QED device to detect a blood ethanol >100 mg/dL. Results: Si xty-six patients were enrolled. The kappa value for QED compared to lab blo od ethanol was 0.93. The Pearson's correlation coefficient was 0.94, The QE D, in general, tended to overestimate blood ethanol slightly. The QED was 1 00% sensitive and 82% specific in detecting a blood ethanol > 100 mg/dL. Co nclusions: Analysis of serum using a QED A350' is a sensitive and accurate index of low to moderate increases in blood ethanol appropriate to emergenc y department, but not legal, interpretation.