Study objective: The validity of self reported smoking in population surveys remains an important question.An associated question is what would be the value of measuring serum cotinine concentrations in such surveys to obtain validated smoking data.Design: Cross sectional analysis of data on self reported smoking and serum cotinine among a random population sample of 5846 persons aged 25 to 64 years, who participated in the FINRISK-92 survey.
Of those participants who reported to have smoked at any time during their life but not during the previous month, 6.3% of men and 5.2% of women had a serum cotinine concentration of at least 10 ng/ml.
Among never smokers 2.5% of men and 2.7% of women had detectable level of cotinine in their serum.
The validity of self reporting was similar among subjects from different areas, ages, and socioeconomic groups.
Conclusions: In a sample of the general population in Finland the validity of self reported smoking is high, and most of the few self reported non-smokers who had cotinine in their serum had only low or moderate levels.
Only a minor fraction of the generated cotinine is excreted by the kidneys, but cotinine is further metabolised to more polar water soluble substances.
According to recent human data the major metabolite found in urine is hydroxylated cotinine.The proportion of reported non-smokers with a cotinine level of at least 14 ng/ml was 4.2%.The misclassification was larger among subjects who were black, had a high school education or less, or were former smokers.The aim of our paper is to study the validity of self reported smoking in a cardiovascular risk factor population survey by comparing self reports with results of measurements of cotinine levels in serum.Nicotine metabolises rapidly and extensively, primarily in the liver.N-oxidation of nicotine to nicotine-1'-N-oxide occurs in humans.