Hong-Jun Cho

Hidden female smokers in Asia: a comparison of self-reported with cotinine-verified smoking prevalence rates in representative national data from an Asian population

Background The low smoking prevalence in Asian women may be due to under-reporting. We therefore investigated gender difference in self-reported and cotinine-verified smoking prevalence rates in Korea Methods We analysed data from 5455 individuals (2387 men and 3068 women) in the 2008 Korean National Health and Nutrition Examination Survey. A urniary cotinine concentration of 50 ng/ml was the cut-off distinguishing smokers from non-smokers. Sensitivity analysis was done using different cut-offs of 25, 75 and 100 ng/ml. Results Cotinine-verified smoking rates were 50.0% for men and 13.9% for women, or 5.3% point and 8.0% point higher in absoulte terms, respectively, than the self-reported rates for men and women. Ratios of cotinine-verified to self-reported smoking rates were 2.36 for women and 1.12 for men. Of the 1620 cotinine-verified smokers, 12.1% of men and 58.9% of women classified themselves as non-smokers. Women who live with a spouse or parents tend to under-report their smoking more than those who live alone or with others. Conclusion Since the number of self-reported female smokers was less than half of cotinine-verified smokers, current anti-smoking policies based on self-reported smoking prevalence rates in Korea should be further directed towards hidden female smokers. Also, biochemical verification needs to be considered with national tobacco surveys in Asian countries.

Explaining age-specific inequalities in mortality from all causes, cardiovascular disease and ischaemic heart disease among South Korean male public servants: relative and absolute perspectives

Objective: To examine age-specific patterns in the ability of major cardiovascular risk factors to explain relative and absolute socioeconomic inequalities in mortality from all causes, cardiovascular disease (CVD), and ischaemic heart disease (IHD). Design: Prospective cohort study. Setting: South Korea. Subjects: 575 377 male public servants aged 30–64 with 16 998 deaths between 1995 and 2003. Main outcomes: All-cause, CVD, and IHD mortality. Results: Four cardiovascular risk factors (cigarette smoking, blood pressure, fasting serum glucose, and serum total cholesterol) were significantly associated with mortality risk. Changing relationships in socioeconomic distribution of risk factors with age were observed. The magnitude of reduction in percent change in absolute risk was greater than that in relative risk. While the risk factors explained only 15.2% of excess RR for all-cause mortality in low-income men aged 30–44, the absolute excess risk of all-cause mortality was reduced by 48.3% when the risk factors were removed from the whole population. This pattern was generally true for all causes, CVD, and IHD, and true for all age groups and risk factors examined. Cigarette smoking and hypertension were the leading contributors in explaining relative and absolute inequality in mortality. Conclusion: Policy efforts to eliminate major cardiovascular risk factors in the general population may have a significant effect on reducing the absolute burden of socioeconomic inequality in mortality. Policy efforts to attenuate socioeconomic inequality in cardiovascular risk factors need to be directed to younger age groups in South Korea.

General and abdominal obesity in South Korea, 1998-2007: gender and socioeconomic differences.

OBJECTIVE To examine national trends in prevalence and socioeconomic inequalities in both general (measured by body mass index) and abdominal obesity (measured by waist circumference) by gender and socioeconomic position (SEP) indicators. METHODS Data were from four rounds of nationally representative cross-sectional surveys for Korean men and women aged 25-64 (6,286 in 1998, 4,839 in 2001, 4,181 in 2005, and 2,006 in 2007). We calculated age-adjusted prevalence rates of overweight and abdominal obesity by gender and SEP indicators (education, occupational class, employment status and income) and examined trends of prevalence and its inequalities. RESULTS Overweight and abdominal obesity has significantly increased in Korean men (P for linear trend <0.01), not in women. For men, high SEP was associated with overweight and abdominal obesity, but the magnitude of socioeconomic differences in obesity measures generally remained unchanged during the study period. Among women, low SEP was associated with overweight. Interestingly, increasing inequalities in abdominal obesity according to education and income were found in women. CONCLUSIONS Clear gender differences were noted in (1) time trends of overweight and abdominal obesity, (2) relationships between the obesity measures and various SEP indicators, and (3) linear time trends of socioeconomic differentials in obesity.

The impact of governmental antismoking policy on socioeconomic disparities in cigarette smoking in South Korea.

INTRODUCTION With enactment of the 1995 Health Promotion Act, the Korean government has developed numerous antismoking policies, including smoke-free buildings and zones, a public media campaign, and tobacco taxation. The present study examined whether governmental antismoking policy during the past decade was associated with reduced socioeconomic differentials in cigarette smoking in South Korea. METHODS Data from 99,980 men and 105,193 women aged 25-64 years were analyzed from four rounds of Social Statistical Surveys of Korea between 1995 and 2006. Socioeconomic position (SEP) indicators were education, occupational class, employment status, and household income. Age-adjusted prevalence of smoking was calculated. Prevalence ratios and the relative index of inequality (RII) were estimated using log-binomial regression analysis. RESULTS Absolute socioeconomic differentials in age-adjusted prevalence of smoking increased between 1995 and 2006. Increases were found in both men and women. Prevalence ratios and RIIs also showed widening relative inequalities in smoking in all four SEP indicators in men. For women, increases in RIIs for education and income were statistically significant. The magnitude of change in prevalence ratios and RIIs by SEP indicators between 1999 and 2003 was statistically significant, whereas the difference between 2003 and 2006 was not. DISCUSSION Despite reducing overall cigarette smoking rates in males, the governmental antismoking policies of South Korea did not reduce socioeconomic inequalities in smoking in both genders. However, the recent tobacco taxation policy is likely to dampen the ever-increasing trends in smoking inequalities. More progressive antismoking policies to reduce socioeconomic inequalities in smoking are warranted in South Korea.

Decomposition of socio-economic differences in life expectancy at birth by age and cause of death among 4 million South Korean public servants and their dependents

BACKGROUND Differences in life expectancy at birth across social classes can be more easily interpreted as a measure of absolute inequalities in survival. This study quantified age- and cause-specific contributions to life expectancy differences by income among 4 million public servants and their dependents in South Korea (9.1% of the total Korean population). METHODS Using 9-year mortality follow-up data (208,612 deaths) on 4,055,150 men and women aged 0-94 years, with national health insurance premiums imposed proportionally based on monthly salary as a measure of income, differences in life expectancy at birth by income were estimated by age- and cause-specific mortality differences using Arriagas decomposition method. RESULTS Life expectancy at birth gradually increased with income. Differences in life expectancy at birth between the highest and the lowest income quartile were 6.22 years in men and 1.74 years in women. Mortality differentials by income among those aged ≥50 years contributed most substantially (80.4% in men and 85.6% in women) to the socio-economic differences in life expectancy at birth. In men, cancers (stomach, liver and lung), cardiovascular diseases (stroke), digestive diseases (liver cirrhosis) and external causes (transport accidents and suicide) were important contributors to the life expectancy differences. In women, the contribution of ill-defined causes was most important. Cardiovascular diseases (stroke and hypertensive disease) and external causes (transport accidents and suicide) also contributed to the life expectancy differences in women while the contributions of cancers and digestive diseases were minimal. CONCLUSIONS Reductions in socio-economic differentials in mortality from stroke and external causes (transport accidents and suicide) among middle-aged and older men and women would significantly contribute to equalizing life expectancy among income groups. Policy efforts to reduce mortality differentials in major cancers (stomach, liver and lung) and liver cirrhosis are also important for eliminating Korean mens socio-economic inequalities in life expectancy.

Family Affluence Scale, other socioeconomic position indicators, and self-rated health among South Korean adolescents: findings from the Korea Youth Risk Behavior Web-based Survey (KYRBWS)

BackgroundPrevious mixed findings regarding socioeconomic differentials among adolescents can be partly attributed to problems in measuring socioeconomic position (SEP) among adolescents. Accordingly, the Family Affluence Scale (FAS) was developed and used in European countries, where it yielded good predictions of socioeconomic differentials in health. However, no prior study has examined whether this new measure for SEP among adolescents is applicable outside Europe.MethodsThe study subjects comprised 71,404 middle and high school students (37,204 boys and 34,200 girls) selected through stratified random cluster sampling of 400 middle schools and 400 high schools in Korea. The predictor variables included the FAS, parental education levels, self-rated school achievement, perceived household economic status, and cohabitation with parents. The outcome variable was self-rated health (SRH); age-adjusted odds ratios were calculated with SRH as an outcome variable.ResultsAbout 10% of the adolescents studied reported “poor” SRH. The correlation coefficients between each component of the FAS were modest (0.11–0.24). Lower FAS was related to a lower level in other SEP indicators and living without parents. All SEP indicators showed a positive relationship between lower SEP and worse SRH for both genders, with gradients being greater among boys than girls. The higher risk of poor SRH being reported by adolescents with low FAS was significantly decreased by adjustment for perceived household economic status.ConclusionSignificant differentials in SRH by many SEP indicators were found among Korean adolescents. The FAS garnered a high completion rate and appeared useful as a measure of SEP for studying adolescents outside of Europe.

Socioeconomic differentials in cause-specific mortality among 1.4 million South Korean public servants and their dependents

Background A growing number of investigations have explored the contribution of cause of death to socioeconomic inequalities in mortality in Europe and North America, but few such studies have been performed on Asian populations. Objectives To analyse the socioeconomic inequality of cause-specific death rates from both an absolute and relative perspective, and to evaluate the contribution of cause of death to total mortality inequality in South Korea. Methods Data were obtained from public servant health insurance beneficiary records. 1 403 297 subjects aged 35–64 years were followed for 9 years. Health insurance premium levels were used as a socioeconomic position indicator. The outcome variables were all-cause, 11 broad causes and 41 specific causes of death. Mortality differentials were examined using cause-specific age-adjusted mortality, relative indices of inequality, and slope inequality indices. Results Graded inverse associations between income and mortality were found for most, but not all, specific causes of death. The major contributors to income differentials in total mortality in men were liver disease (15.4%), stroke (12.8%), land transport accidents (10.0%), lung cancer (7.1%) and liver cancer (7.0%). In women, stroke (30.7%), diabetes (9.1%), land transport accidents (6.6%), liver cancer (6.0%) and liver disease (5.1%) were important. Conclusions The contribution of the cause of death to socioeconomic inequality in mortality in South Korea differed from Western countries. To develop a policy to reduce the magnitude of socioeconomic inequality, an understanding of the major causes of death that contribute to mortality inequality is required.

Changes in contribution of causes of death to socioeconomic mortality inequalities in Korean adults.

Objectives This study aimed to analyze long-term trends in the contribution of each cause of death to socioeconomic inequalities in all-cause mortality among Korean adults. Methods Data were collected from death certificates between 1990 and 2004 and from censuses in 1990, 1995, and 2000. Age-standardized death rates by gender were produced according to education as the socioeconomic position indicator, and the slope index of inequality was calculated to evaluate the contribution of each cause of death to socioeconomic inequalities in all-cause mortality. Results Among adults aged 25-44, accidental injuries with transport accidents, suicide, liver disease and cerebrovascular disease made relatively large contributions to socioeconomic inequalities in all-cause mortality, while, among adults aged 45-64, liver disease, cerebrovascular disease, transport accidents, liver cancer, and lung cancer did so. Ischemic heart disease, a very important contributor to socioeconomic mortality inequality in North America and Western Europe, showed a very low contribution (less than 3%) in both genders of Koreans. Conclusions Considering the contributions of different causes of death to absolute mortality inequalities, establishing effective strategies to reduce socioeconomic inequalities in mortality is warranted.