Saliva cotinine levels in smokers and nonsmokers

The authors collected by mail self-reported data on smoking habits and sali va samples that were analyzed for cotinine concentration in 222 smokers and 97 nonsmokers. Participants were members of the University of Geneva (Swit zerland) in 1995. The 207 cigarette-only smokers smoked on average 10.7 cig arettes/day and had a median concentration of cotinine of 113 ng/ml. The co tinine concentration was moderately associated with the number of cigarette s smoked per day (+14 ng/ml per additional cigarette, p < 0.001, R-2 = 0.45 ) and was 54 ng/ml higher in men than in women after adjustment for cigaret tes per day and for the Fagerstrom Test for Nicotine Dependence. The cotini ne level was not associated with the nicotine yield of cigarettes (r = 0.08 ). In nonsmokers, the median concentration of cotinine was 2.4 ng/ml. The c otinine concentration was 1.5 times higher in nonsmokers whose close friend s/spouses were smokers than in nonsmokers whose close friends/spouses were nonsmokers (p = 0.05). A cutoff of 7 ng/ml of cotinine distinguished smoker s from nonsmokers with a sensitivity of 92.3% and a specificity of 89.7%; a cutoff of 13 ng/ml provided equally satisfactory results (sensitivity, 86. 5%; specificity, 95.9%). This study provides evidence for the construct val idity of both questionnaires and saliva cotinine for the assessment of acti ve and passive exposure to tobacco smoke.