Trends in socio-economic differentials in cigarette smoking behaviour between 1990 and 1998: a large prospective study in Korean men

Objectives. To investigate the magnitude and time trends in socio-economic differentials in cigarette smoking behaviour. designs. A prospective observational study of male civil servants followed-up for 8 years. g. All civil service offices in Korea. ipants. A total of 322,991 male civil servants aged 30–49 years on whom information on monthly salary was available and who had reported cigarette smoking behaviour between 1990 and 1998. s. Smoking prevalence was 60.1% in 1990 and was inversely associated with salary level. The difference in smoking prevalence between the highest and the lowest salary groups gradually widened from 13.0% in 1990 to 16.1% in 1998. The relative index of inequality (RII) as a measure of socio-economic inequality in smoking behaviour was 1.91 [95% confidence interval (CI) 1.86–1.97] in 1990 and increased between 1990 and 1998. The RII for smoking cessation was 0.60 in 1990 (95% CI 0.58–0.62) and gradually decreased as time lapsed. sions. An increasing trend in socio-economic inequality in smoking behaviour was observed in this study.