engleski

Estimation of urinary cotinine cut-off value to discern pregnant at term cigarette smokers from non-smokers

Prenatal exposure to cigarette smoking has been extensively studied as one of the factors that may have adverse health outcomes later in life. Reliance on self-reported smoking behaviour may lead to understatements of nicotine exposure due to negative social connotations related to maternal smoking. To overcome the uncertainty of self-reporting, cotinine, the major metabolite of nicotine in urine, is widely used as a reliable biomarker of tobacco smoke exposure. Since half- life of cotinine is much shorter in pregnant (8.8 h) vs. non-pregnant women (16.6 h), cut-off level to classify non-smokers and active smokers must be established for pregnancy. The aim of this study was to determine a cut-off value to discern pregnant non-smokers from pregnant smokers. Spot urine samples from pregnant women self-reported as non-smokers (n = 117 ; never smoked or smoked >12 months before the last pregnancy) or smokers (n = 39, smoking any time during pregnancy or within 12 months before last pregnancy) were collected in the maternity ward before delivery. Cotinine was extracted from urine by headspace solid phase microextraction and quantified using gas chromatography-mass spectrometry. A receiver operating characteristic (ROC) curve analysis showed that the optimal cut-off value of urinary cotinine to discern pregnant non-smokers from smokers was 24.1 μg/L (42.6 μg/g creatinine). Misclassification rate for current smokers who reported no smoking was 5.1 %. The presented cut- off value for urinary cotinine ensures a more accurate categorisation of the smoking habit among pregnant women than by self-reporting. The study was funded by the Croatian Science Foundation (grant HRZZ-IP-2016-06-1998).

biomarker of cigarette smoking ; gas chromatography-mass spectrometry ; ROC curve ; solid phase microextraction ; spot urine.

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