Clinical Utility of a Saliva Alcohol Dipstick Estimate of Serum Ethanol Concentrations in the Emergency Department

Abstract

Rapid determination of serum ethanol concentrations can be a useful adjunct in evaluating patients with decreased levels of consciousness. Previous reports suggest that saliva ethanol concentrations measured by a colorimetric saliva dipstick assay correlate well with serum ethanol concentrations and could be useful in the emergency department. We compared saliva dipstick assay results with concurrent serum ethanol measurements in 67 emergency department patients with altered mental status. Color changes of the stick are calibrated to reflect serum ethanol concentrations of negative (no color change), 4.3 mmol/L, 10.8 mmol/L, 21.7 mmol/L, and ≥ 65.1 mmol/L. Emergency department staff were instructed to conduct the measurement according to the manufacturer's directions and round up equivocal results to the next highest concentration. Serum ethanol concentrations (mean ± SD) grouped by dipstick results were: negative, 5.2 ± 13.1 mmol/L; 4.3 mmol/L, 29.1 ± 18.0 mmol/L; 10.8 mmol/L, 46.6 ±27.6 mmol/L; 21.7 mmol/L, 47.0 ± 18.5 mmol/L; and 65.1 mmol/L, 62.4 ± 24.2 mmol/L. There were 12 false-negative and 2 false-positive results. Correlation between dipstick results and serum ethanol concentrations was rho = 0.611 (p<0.0005). The lack of accuracy of the saliva dipstick measurements and the high number of false-negative results make it a poor choice for determining alcohol use in the emergency department patient.