Measuring tobacco use in a prison population

Abstract

Introduction: Widespread tobacco use and high interest in quitting make prisons an ideal environment for smoking cessation interventions; however, little has been done to assist prisoners in their efforts to quit. Valid measurement of tobacco use is a prerequisite to evaluation of cessation programs, yet there has been only one published examination of tobacco use measures among prisoners. Methods: Tobacco use interviews were conducted with 200 male prisoners. Three measures of tobacco use, exhaled carbon monoxide (eCO), salivary cotinine measured by enzyme immunoassay (EIA), and salivary cotinine measured by liquid chromatography/tandem mass spectrometry (LC/MS/MS), were evaluated using self-reported tobacco use as the reference. Optimum cutpoints were identified by maximization of the Youden index. Results: Carbon monoxide breath testing, though the poorest performing of the three measures examined, still had excellent discrimination (cutpoint ≥ 4 ppm, sensitivity = 88.3%, specificity = 94.9%). Cotinine EIA performed better than eCO (cutpoint ≥ 10 ng/ml, sensitivity = 92.2%, specificity = 94.3%) but poorer than cotinine LC/MS/MS (cutpoint ≥ 9 ng/ml, sensitivity = 98.6%, specificity = 97.8%). Discussion: eCO had the poorest performance as a standalone test, though validity of the test may be improved with increased frequency of testing. False-negative results using cotinine EIA limit its utility as a standalone test, however, as part of a twostage screening process it may reduce the cost of testing. Cotinine LC/MS/MS, while most expensive, was the most accurate standalone measure of prisoners' tobacco use. © The Author 2010. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved.