The performance of saliva test strips for determining ethanol levels, as compared to gas chromatography and breathalyser methods

Abstract

We set out to determine the performance of the Testi Technologies enzymatic assay saliva ethanol test strips of three different detection levels: 0 g/L, 0.2 g/L and 0.5 g/L, using as the reference method a gas chromatography analyser (GC). Alcohol levels were measured in 104 volunteers at up to three points in time, using up to three test strips per measurement, while gathering blood samples and breathalyser readings in parallel. The plasma alcohol concentrations (PAC) were determined from the plasma samples using GC. The qualitative results of the test strips were compared to the quantitative results from the reference method, as well as the breathalyser readings, and the amount of true and false positive and true and false negative results were classified using predetermined cut-off levels. The best performing test strips were the 0 g/L and the 0.2 g/L strips. The 0 g/L strips had a sensitivity and specificity of 1.00, as false negatives and false positives were not detected. The 0.2 g/L strips had a sensitivity and specificity [95% confidence interval (CI)] of 0.98 (0.96 − 1.00) and 0.83 (0.62 − 1.00) respectively, an accuracy of 0.97 (0.95 − 0.99), and a diagnostic odds ratio of 205.00 (35.33 − 1189.66). The test strips perform their intended purpose of screening for alcohol consumption well, with their great sensitivity as a defining property compared to other testing methods. For them to be able to be implemented in a clinical setting however, further refinement of the tests’ characteristics would be required.

Keywords:

• Alcohol (ethanol)
• saliva test
• enzymatic assay
• gas chromatography
• breathalyser

Acknowledgements

We would like to thank Paula Reponen, Jaana Holappa-Girginkaya, Marja Nissinen and their students Sari Hägg, Heli Limma, Saara Korkala and Elina Niskala from Oulu University of Applied Sciences for handling the volunteer recruiting, experimental setup and sample gathering portions of this study.

Disclosure statement

This study was performed in cooperation with Testi Technologies Inc, who supplied the test strips used in the experiment. GC-analysis and interpretation of all results was performed independently of the test strip manufacturer.