Determination of a saliva cotinine cut‐off to distinguish pregnant smokers from pregnant non‐smokers

Abstract

Background. Objective validation of smoking status is necessary. Earlier studies have used saliva cotinine concentrations between 14.2 and 30 ng/ml as cut-off values to distinguish pregnant smokers from non-smokers. However, these cut-offs derive from studies including men and non-pregnant women. This constitutes a problem, as recent studies have reported an accelerated metabolism in pregnant smokers. The aim of this study was to determine the optimum cut-off cotinine level distinguishing pregnant smokers from pregnant non-smokers. Methods. An observational study of 620 pregnant women, 359 self-reported smokers and 261 self-reported non-smokers, with complete data on smoking status and saliva cotinine. The study was conducted at a large university hospital in Copenhagen, Denmark. Saliva was sampled at the first antenatal visit to the midwife and analyzed for cotinine level by gas chromatography. Participants completed a questionnaire immediately after the first visit. Results. A saliva cotinine cut-off level of 13 ng/ml, corresponding to a sensitivity of 0.99 and specificity 0.98, was found to be the optimum cut-off value separating pregnant smokers from non-smokers. The sum of the sensitivity and specificity was at its maximum, 1.981. A 95% bootstrap confidence interval for the optimum cut-off was (8 Á14 ng/ml). Conclusion. From the present data we recommend that in future studies on smoking cessation and pregnancy a cut-off level of 13 ng/ml should be applied to distinguish between pregnant smokers and non-smokers.

Nicotine and metabolites in meconium as evidence of maternal cigarette smoking during pregnancy and predictors of neonatal growth deficits

“…It is well established that self-reported tobacco use often is misrepresented by pregnant women (England et al, 2007;Gray, LaGasse, et al, 2009). The 10 ng/ml oral fluid cutoff to differentiate smokers from nonsmokers is slightly lower than previous reports by Hegaard, Kjaergaard, Moller, Wachmann, and Ottesen (2007), 13 ng/ml; Owen and McNeill (2001),14 ng/ml; and Boyd et al (1998), 30 ng/ml but correspond to levels probable for regular nicotine use, as suggested by Etzel (1990) and Parazzini et al (1996). Furthermore, the 10 ng/ml cutoff was recommended by the Society for Research on Nicotine and Tobacco Subcommittee on Biochemical Verification (Benowitz et al, 2002).…”

Fetal growth restriction triggered by polycyclic aromatic hydrocarbons is associated with altered placental vasculature and AhR-dependent changes in cell death

“…Self-reporting of smoking behavior in pregnant women has been shown to impart a certain degree of bias (30,35), because some women who smoke falsely report a "nonsmoking" status (54). In addition, although testing for carbon monoxide and cotinine (a metabolite of nicotine) levels can more accurately reflect exposure to tobacco smoke, these tests have been shown to be problematic in pregnant women (42,80) because of their higher capacity for nicotine metabolism (24). These issues underscore the need for a satisfactory animal model to elucidate the affected molecular pathways upon PAH exposure before and during gestation.…”

Benefits of Incentives for Breastfeeding and Smoking cessation in pregnancy (BIBS): a mixed-methods study to inform trial design

“…123 Saliva levels are thought to mirror plasma levels, with a cut-off of 13 ng/ml quoted for pregnant smokers in a recent study. 124 Urine cotinine levels are in theory more problematic in that the cotinine level should be corrected for dilution by measuring creatinine in the urine. In practice, the dilution effect may not be important and laboratories differ, with a cut-off of around 44.7 ng/ml.…”