Assessment of the accuracy of salivary cotinine readings from NicAlert strips against a liquid chromatography tandem mass spectrometry assay in self-reported non-smokers who passed carbon monoxide but failed NicAlert validation.

BACKGROUND AND AIMS

NicAlert produces semi-quantitative assessments of cotinine levels in saliva or urine for verification of smoking abstinence. This study aimed to assess the accuracy of NicAlert readings against a liquid chromatography tandem mass spectrometry assay in smokers who had passed expired-air carbon monoxide (CO) verification but failed NicAlert verification.

DESIGN

Comparison of NicAlert readings against readings from a reference assay using liquid chromatography tandem mass spectrometry.

SETTING

Geneva, Switzerland.

PARTICIPANTS

Self-reported non-smokers (n = 92) who in previous testing had CO of 0-3 parts per million (indicating no recent smoking) and reported not using any nicotine product, but had NicAlert readings ≥ 1 (indicating smoking).

MEASUREMENTS

NicAlert produces readings of 0, 1 and 2+, which are reported by the manufacturer to correspond to saliva cotinine concentrations of 0-10 ng/ml (indicating not smoking), 10-30 ng/ml and 30+ ng/ml, respectively. Liquid chromatography tandem mass spectrometry was used as the reference.

FINDINGS

For 82 participants with a NicAlert reading of 1, only two of the liquid chromatography tandem mass spectrometry values were within the purported range of 10-30 ng/ml; 71 were below 4 ng/ml and half the values were below 0.5 ng/ml. Two of the eight participants with NicAlert readings of 2 had laboratory values within the designated range. Neither of the two participants with NicAlert readings of 3 had a cotinine value within the designated range.

CONCLUSIONS

In people who had passed carbon monoxide verification, NicAlert readings yielded a very high false-positive rate in detecting levels of cotinine indicative of smoking.