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 bothself-reports of smoking and urinary cotinine data, revealed a significant discrepancy between the prevalence ofself-reported and biochemically-verified female smokers. The factors associated with accurate self-reporting ofcurrent smoking status remain poorly understood, however. Materials and
Methods: We assessed the prevalenceof smoking in KNHANES using both self-report and urinary cotinine data. Subsequently, using univariate andmultivariate 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 selfreportingin Korean females. We also investigated whether the prevalence of inaccurate self-reports changedover the survey period, 2008-2009.
Results: The prevalence of self-reported smoking was 47.8% in males and6.6% in females. By contrast, the prevalence of smoking as assessed by urinary cotinine levels was 52.2% inmales and 14.5% in females. Of the 746 females with urinary cotinine levels >50ng/ml, 407 (56.0%) providedinaccurate 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<0.001), marital status (married but without spouse: OR0.37, 95%CI 0.15-0.94, p=0.037; ref :never married), relationship with cohabitants (living with a spouse andunmarried child: OR 2.63, 95%CI 1.44-4.80, p=0.002; living with 2 generations except unmarried child: OR 2.53,95%CI 1.09-5.87, p=0.030; living with ≥3 generations: OR 3.25, 95%CI 1.48-7.10, p=0.003; ref :spouse only) andeducation(college or higher: OR 2.73, 95%CI 1.04-7.18, p=0.042; ref :elementary or less) were independentlyassociated with inaccurate self-reports.
Conclusions: The trend of smoking prevalence of Korean females is likelyto decrease. However, an elevated prevalence of inaccurate self-reports by females remains. Factors related tothe intensity of smoking and family status appear to influence whether a Korean female provides an accurateself-report when asked about smoking behavior.