Biochemically-verified Smoking Rate Trends and Factors Associated with Inaccurate Self-reporting of Smoking Habits in Korean Women

Background: Lung cancer is a major cause of Korean female mortality and is clearly associated with smoking. The Korean National Health and Nutrition Examination Survey (KNHANES IV-2,3), which included both self-reports of smoking and urinary cotinine data, revealed a significant discrepancy between the prevalence of self-reported and biochemically-verified female smokers. The factors associated with accurate self-reporting of current smoking status remain poorly understood, however. Materials and Methods: We assessed the prevalence of smoking in KNHANES using both self-report and urinary cotinine data. Subsequently, using univariate and multivariate tests, we assessed whether age, intensity of smoking, marital status, relationship with cohabitants, education, occupation, residential area, or annual household income were associated with inaccurate self-reporting in Korean females. We also investigated whether the prevalence of inaccurate self-reports changed over the survey period, 2008-2009. Results: The prevalence of self-reported smoking was 47.8% in males and 6.6% in females. By contrast, the prevalence of smoking as assessed by urinary cotinine levels was 52.2% in males and 14.5% in females. Of the 746 females with urinary cotinine levels >50ng/ml, 407 (56.0%) provided inaccurate self-reports. In a multivariate model, age group(40-49: OR 3.54, 95%CI 1.42-8.86, p=0.007; ref :20-29), cotinine intensity(OR 0.999, 95%CI 0.998-0.999, p