The data of women who participated in 2008 Seoul CHS were used. The survey methodology has been previously detailed.¹⁶⁾ The survey was performed between September and November 2009 and the target population of the survey was anyone ≥19-years-of-age residing in Seoul during the survey period. The trained interviewers visited the samples of households and conducted face-to-face interviews on all adults in the households. Total participants of the survey were 21,928 individuals. Among them, 9,096 individuals were women aged 25-64 years. Seven women who did not answer any smoking questions were excluded from the present study. Finally, the data of 9,089 women were available for the final analyses.

Study subjects were classified into ever smokers if they reported that they had smoked at least 100 cigarettes during their lifetime and non-smokers if they reported that they had never smoked or had smoked fewer than 100 cigarettes in their lifetime. Ever smokers were subclassified into current smokers, who currently smoked, and ex-smokers, who did not currently smoke. Smoking initiation rate was defined as the proportion of the individuals who had started smoking at least one cigarette among the total study subjects. Smoking cessation rate was calculated by dividing the number of individuals who had quit smoking by the number of ever smokers.

Education level, total family income and occupation were investigated as socioeconomic indicators. Education level was classified as less than or achievement of graduation of middle school, graduation from high school and more than or achievement of graduation of college. For economic status, household equivalent income was calculated by dividing total family income by the square root of the number of family members. The calculated household equivalent income was categorized as tertiles (high, middle, and low). Occupation was classified into three occupational groups of non-manual workers, manual workers and the others by the Korean Standard Classification of Occupation revised in 2007. While 1) managers, 2) professionals and related workers, 3) clerks were included in non-manual workers, 4) service workers, 5) sales workers, 6) skilled agricultural, forestry and fishery workers, 7) craft and related trade workers, 8) equipment, machine operating and assembling workers, and 9) elementary workers were included in manual workers. Additionally, soldiers, students, homemakers, and unemployed were classified as others. Marital status was categorized into three groups: married, unmarried, and others (divorced, separated, or widowed). Drinking status was classified into two groups by frequency of alcohol intake: <1 time a month or ≥1 time a month.

Every analysis was performed by taking into account sample weights, stratification and primary sampling units from CHS. Data were expressed as percentage ± standard error. Logistic regression analyses were used to obtain odds ratios (ORs) and 95% confidence interval (CI) of each socioeconomic indicators on initiation and cessation of smoking. There was likely no problem concerning multicollinearity because all values of the variance inflation factor for independent variables in the regression models were <2.0. All statistical analyses were performed with PASW ver. 18.0 (SPSS Inc., Chicago, IL, USA) and P-values < 0.05 was considered statistically significant.

The mean age of the study subjects was 42.2 ± 1.1 years (range, 25 to 64 years). Sociodemographic characteristics of the study subjects with smoking status are shown in Table 1. The initiation rate and the cessation rate of smoking in total subjects were 6.4 ± 0.3% and 27.3 ± 2.0%, respectively. Both smoking initiation and cessation rate was highest in 25-34 age group.

OR and 95% CI of each socioeconomic indicator on smoking initiation are presented in Table 2. Compared to women who graduated from college, women who did not graduate from college had a higher likelihood of smoking initiation (high school: OR, 1.35, 95% CI, 1.04 to 1.75; ≤middle school: OR, 1.72, 95% CI, 1.17 to 2.51). Smoking initiation was significantly higher in women who had manual jobs (OR, 1.65; 95% CI, 1.20 to 2.27) or other jobs (OR, 1.37; 95% CI, 1.01 to 1.87) than in women who had non-manual jobs. Age-adjusted OR of the low income group (1.74; 95% CI, 1.35 to 2.24) compared to the high income group was statistically significant. However, significance was not apparent following adjustment by marital status, alcohol intake, education level and occupation. Smoking initiation rate was higher in younger women and unmarried, divorced, separated and widowed women. Smoking initiation rate in women whose frequency of alcohol intake was ≥1 time/mo was more than twice as great as women whose frequency of alcohol intake was <1 time/mo.

Data on OR and 95% CI of each socioeconomic indicators on smoking cessation are presented in Table 3. Compared to women who graduated from college, women who did not graduate from college had a lower likelihood of smoking cessation (high school: OR, 0.30, 95% CI, 0.20 to 0.44; ≤middle school: OR, 0.38, 95% CI, 0.22 to 0.66). Smoking cessation rate was not significantly different between manual workers and non-manual workers, but was higher in women who had other jobs (OR, 1.51; 95% CI, 1.03 to 2.21) than in women who had non-manual jobs. There was not a significant relationship between household income level and smoking cessation. The smoking cessation rate was higher in younger women and married women. Smoking cessation rate in women whose frequency of alcohol intake was <1 time/month was about 1.7-times higher than that in women whose frequency of alcohol intake was ≥1 time/month.