Figure 3
From: Assessment of smoking status based on cotinine levels in nasal lavage fluid
Distribution of NLF cotinine across all subjects. NLF cotinine level of 1 ng/mL was lowest concentration as a cutoff point to distinguish nonsmokers from smokers with the best combined levels of sensitivity (91%) and specificity (99%). Similar cutoff levels were obtained in men and women (not shown). NLF cotinine levels lower than 1 ng/mL were observed in 100% of the self-reported non-exposed nonsmokers and in more than 90% of self-reported nonsmokers ETS.