Urine Cotinine Concentrations for Assessing Tobacco Smoke Exposure in Korean: Analysis of the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV)

Abstract

PURPOSE: Cotinine is a major metabolite of nicotine and the level of urine cotinine is an indicator of tobacco smoke exposure, including passive smoke. The purpose of this study is to investigate the role of urine cotinine for assessing the smoking status of persons exposed to tobacco smoke in Korean. METHODS: During 2008, the second year of Korea National Health and Nutrition Examination Survey (KNHANES) IV, 500 survey areas were drawn from a census of population and housing by considering the proportion of each subgroup. Trained interviewers administered a questionnaire on smoking status and other health information. Urine cotinine levels were measured by gas chromatography mass spectrometry using Perkin Elmer Clarus 600T (PerkinElmer/Finland). All data were measured by standard manner and reviewed by central quality control center. Non -smokers were divided into three groups according to passive smoking exposure duration in the workplace: non-exposure, exposure duration is less than 1 hour and more than 1 hour. RESULTS: Urine cotinine levels were measured in 8,931 adults aged more than 18. Among them, 2535 were men (44.2%) and 3198 were women (53.8%). Smokers were 2268(39.6%) and non smokers were 3465(60.4%). The mean urine cotinine levels were 719.1ng/mL in smokers and 30.6ng/mL in non-smokers. In smokers, urine cotinine levels of smokers (mean value: 1214.4) were higher than exsmokers (mean value: 67.5). Among non-smokers, the mean urine cotinine levels were 29.6 in non-exposure, 60.0 in exposure duration less than 1 hour group and 99.2 ng/mL in exposure duration more than 1 hour group. Optimal urine cotinine concentrations for discriminating non-smokers from smokers were determined using receiver operator characteristic curve analysis. Optimal cut-off point was 39.5 ng/mL (sensitivity = 83.6%, specificity = 96.5%). Among non-smokers, optimal cut-off point for distinguishing non-exposure from passive exposure was 9.42 ng/mL (sensitivity = 53.0%, specificity = 57.1%). CONCLUSIONS: Urine cotinine concentration is a useful biomarker for discriminating non-smokers from smokers. CLINICAL IMPLICATIONS: Careful interpretation is necessary for assessing passive smoking status by urine cotinine concentration in Korean.