Health & body · 2014
How well did personal breathalysers detect people at or above the driving limit?
One of three devices detected just 26.3% of participants who were at or above the limit according to a police breathalyser. The other two detected about 90% or more, though all estimates were uncertain.
Details
Researchers assessed the diagnostic accuracy of three personal breathalysers sold to the public and marketed to test whether it was safe to drive after drinking. In a prospective comparative diagnostic accuracy study, they compared two single-use breathalysers and one digital multiuse breathalyser (the index tests) with a police breathalyser (the reference test). The study took place in establishments licensed to serve alcohol in a UK city. Of 222 people recruited, 208 were included in the main analysis. Eligible participants were at least 18 years old, had consumed alcohol and did not intend to drive in the following 6 hours.
The researchers measured and for detecting a breath alcohol concentration at or above the UK legal driving limit of 35 µg/100 mL. According to the police breathalyser, 18% of participants (38/208) were at or above that limit. The digital multiuse device had a sensitivity of 89.5% (95% confidence interval [CI] 75.9%–95.8%) and a specificity of 64.1% (95% CI 56.6%–71.0%). The two single-use devices had sensitivities of 94.7% (95% CI 75.4%–99.1%) and 26.3% (95% CI 11.8%–48.8%), and specificities of 50.6% (95% CI 40.4%–60.7%) and 97.5% (95% CI 91.4%–99.3%), respectively. A self-reported alcohol consumption threshold of 5 UK units or fewer had higher sensitivity than all the personal breathalysers.
The researchers concluded that the device with 26% sensitivity would falsely reassure approximately three in four people who were over the limit by the reference standard, at least on the evening of drinking. The other tested devices had sensitivity of 90% or higher, as rounded in the conclusion. All estimates were subject to uncertainty. There is no clearly defined minimum sensitivity for this safety-critical application. The researchers concluded that current regulatory frameworks do not ensure high sensitivity for devices marketed to consumers for a decision with potentially catastrophic consequences.
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