Income-related inequality in quality-adjusted life expectancy in Korea at the national and district levels.

BACKGROUND: The aim of this study was to measure differences in quality-adjusted life expectancy (QALE) by income in Korea at the national and district levels. METHODS: Mortality rates and EuroQol-5D (EQ-5D) scores were obtained from the National Health Information Database of the National Health Insurance Service and the Korea Community Health Survey, respectively. QALE and differences in QALE among income quintiles were calculated using combined 2008-2014 data for 245 districts in Korea. Correlation analyses were conducted to investigate the associations of neighborhood characteristics with QALE and income gaps therein. RESULTS: QALE showed a graded pattern of inequality according to income, and increased over time for all levels of income and in both sexes, except for low-income quintiles among women, resulting in a widened inequality in QALE among women. In all 245 districts, pro-rich inequalities in QALE were found in both men and women. Districts with higher QALE and smaller income gaps in QALE were concentrated in metropolitan areas, while districts with lower QALE and larger income gaps in QALE were found in rural areas. QALE and differences in QALE by income showed relatively close correlations with socioeconomic characteristics, but relatively weak correlations with health behaviors, except for smoking and indicators related to medical resources. CONCLUSIONS: This study provides evidence of income-based inequalities in health measured by QALE in all subnational areas in Korea. Furthermore, QALE and differences in QALE by income were closely associated with neighborhood-level socioeconomic characteristics.

Long-term trends in smoking prevalence and its socioeconomic inequalities in Korea, 1992-2016.

BACKGROUND: The aim of this study was to investigate long-term trends in smoking prevalence and its socioeconomic inequalities in Korea. METHODS: Data were collected from 10 rounds of the Social Survey of Statistics Korea between 1992 and 2016. A total of 524,866 men and women aged 19 or over were analyzed. Age-adjusted smoking prevalence was calculated according to three major socioeconomic position indicators: education, occupational class, and income. The prevalence difference, prevalence ratio, slope index of inequality (SII), and relative index of inequality (RII) were calculated to examine the magnitude of inequality in smoking. RESULTS: Smoking prevalence among men decreased from 71.7% in 1992 to 39.7% in 2016, while smoking prevalence among women decreased from 6.5% in 1992 to 3.3% in 2016. Socioeconomic inequalities in smoking prevalence according to the three socioeconomic position indicators were found in both men and women throughout the study period. In general, absolute and relative socioeconomic inequalities in smoking, measured by prevalence difference and prevalence ratio for education and occupational class, widened during the study period among Korean men and women. In men, the SII for income increased from 7.6% in 1999 to 10.8% in 2016 and the RII for income also increased from 1.11 in 1999 to 1.31 in 2016. In women, the SII for income increased from 0.1% in 1999 to 2.4% in 2016 and the RII for income increased from 1.39 in 1999 to 2.25 in 2016. CONCLUSION: Pro-rich socioeconomic inequalities in smoking prevalence were found in men and women. Socioeconomic inequalities in smoking have increased in parallel with the implementation of tobacco control policies. Tobacco control policies should be developed to decrease socioeconomic inequalities in cigarette use in Korea.

Comparison of Prevalence- and Smoking Impact Ratio-Based Methods of Estimating Smoking-Attributable Fractions of Deaths.

BACKGROUND: Smoking is a major modifiable risk factor for premature mortality. Estimating the smoking-attributable burden is important for public health policy. Typically, prevalence- or smoking impact ratio (SIR)-based methods are used to derive estimates, but there is controversy over which method is more appropriate for country-specific estimates. We compared smoking-attributable fractions (SAFs) of deaths estimated by these two methods. METHODS: To estimate SAFs in 2012, we used several different prevalence-based approaches using no lag and 10- and 20-year lags. For the SIR-based method, we obtained lung cancer mortality rates from the Korean Cancer Prevention Study (KCPS) and from the United States-based Cancer Prevention Study-II (CPS-II). The relative risks for the diseases associated with smoking were also obtained from these cohort studies. RESULTS: For males, SAFs obtained using KCPS-derived SIRs were similar to those obtained using prevalence-based methods. For females, SAFs obtained using KCPS-derived SIRs were markedly greater than all prevalence-based SAFs. Differences in prevalence-based SAFs by time-lag period were minimal among males, but SAFs obtained using longer-lagged prevalence periods were significantly larger among females. SAFs obtained using CPS-II-based SIRs were lower than KCPS-based SAFs by >15 percentage points for most diseases, with the exceptions of lung cancer and chronic obstructive pulmonary disease. CONCLUSIONS: SAFs obtained using prevalence- and SIR-based methods were similar for males. However, neither prevalence-based nor SIR-based methods resulted in precise SAFs among females. The characteristics of the study population should be carefully considered when choosing a method to estimate SAF.

Sensation seeking as a potential screening tool for suicidality in adolescence.

BACKGROUND: Although suicide could be an adverse health problem related to sensation seeking, this relationship has not been rigorously evaluated. The purpose of this study was to evaluate the relationship between sensation seeking and suicidality (suicidal ideation and plan) among adolescents and to test the influence of depressive symptom on this relationship. METHODS: We surveyed 2,017 adolescents in seven middle and high schools located in urban and rural areas in 2012. A self-report questionnaire included items about demographic characteristics, sensation seeking, depressive symptom, and suicide plans. We evaluated the influence of sensation seeking on suicide plan using multiple logistic regression and causal mediation analysis. RESULTS: Sensation seeking was related to suicide ideation and plan. Sensation seeking was associated with a 13 % greater likelihood of a suicide plan during the past 12 months as the score increased by 1. After controlling for depressive symptom, the effect of sensation seeking was reduced, but still significantly increased the risk (adjusted odds ratio: 1.10; 95 % CI: 1.04-1.16). When depressive symptom was included as a potential mediator, depressive symptom exerted an indirect effect on suicide planning that constituted 37 % of the total effect of sensation seeking. There was no significant interaction between sensation seeking and either demographic variables or depressive symptom. CONCLUSIONS: Sensation seeking can contribute to developing a suicide plan directly and indirectly via depressive symptom. Sensation seeking could be used to identify high-risk adolescents and provide proper interventions.

Disability-adjusted Life Years (DALYs) for Mental and Substance Use Disorders in the Korean Burden of Disease Study 2012.

The purpose of this study was to estimate the national burden of mental substance disorders on medical care utilization in Korea using National Health Insurance System (NHIS) data and updated disability weight, in terms of disability-adjusted life years (DALYs). For each of the 24 disorders, the incident years lived with disability (YLDs) was calculated, using NHIS data to estimate prevalence and incidence rates. The DisMod-II software program was used to model duration and remission. The years of life lost (YLLs) due to premature death were calculated from causes of death statistics. DALYs were computed as the sum of YLDs and YLLs, and time discounting and age weighting were applied. The year examined was 2012, and the subjects were divided into 9 groups according to age. In 2012, the Korean burden of mental and substance use disorders was 945,391 DALYs. More than 98% of DALYs were from YLDs, and the burden in females was greater than that in males, though the burden in males aged less than 19 years old was greater than that in females. Unipolar depressive disorders, schizophrenia, and anxiety disorders were found to be major diseases that accounted for more than 70% of the burden, and most DALYs occurred in their 30-59. Mental and substance use disorders accounted for 6.2% of the total burden of disease and were found to be the 7th greatest burden of disease. Therefore, mental and substance use disorders need to be embraced by mainstream health care with resources commensurate with the burden.

Disability-Adjusted Life Years (DALYs) for Injuries Using Death Certificates and Hospital Discharge Survey by the Korean Burden of Disease Study 2012.

A system for assessing the burdens imposed by disease and injury was developed to meet healthcare, priority setting, and policy planning needs. The first such system, the Global Burden of Disease (GBD), was implemented in 1990. However, problems associated with limited data and assumed disability weightings remain to be resolved. The purpose of the present study was to estimate national burdens of injuries in Korea using more reliable data and disability weightings. The incidences of injuries were estimated using the Korean National Hospital Discharge Survey and the mortality data from the Korean National Statistical Office in 2010. Additionally, durations of injuries and age at injury onset were used to calculate disability-adjusted life years (DALY) using disability weightings derived from the Korean Burden of Disease (KBD) study. Korea had 1,581,072 DALYs resulting from injuries (3,170 per 100,000), which was 22.9% higher than found by the GBD 2010 study. Males had almost twice as heavy an injury burden as females. Road injury, fall, and self-harm ranked 1st, 2nd, and 3rd in terms of burden of injury in 2010. Total injury burden peaked in the forties, while burden per person declined gradually from early adulthood. We hope that this study contributes to the reliable evaluation of injury burden and a better understanding of injury-related health status using nation-specific, dependable data.

Disability-adjusted Life Years for 313 Diseases and Injuries: the 2012 Korean Burden of Disease Study.

This study is part of a 5-year research project on the national burden of diseases, injuries, and risk factors in Korea. Using disability-adjusted life years (DALYs), a metric introduced by the 1990 Global Burden of Disease (GBD) project, we performed a comprehensive and detailed assessment of the magnitude and distribution of both fatal and non-fatal health problems in the Korean population. The concept and general approach were consistent with the original GBD study, with some methodological modifications to make the study more suitable for Korea. We computed DALYs for 313 causes in both sexes and nine age groups using the entire population's medical records and newly generated Korean disability weights. In 2012, the dominant disease burden was non-communicable diseases, which accounted for 85.21% of total DALYs, while injuries accounted for 7.77% and communicable, maternal, neonatal, and nutritional disorders for 7.02%. Of the total DALYs, 88.67% were from years lived with disability and 11.32% were from years of life lost due to premature mortality. Diabetes mellitus was the leading cause of DALYs, followed by low back pain, chronic obstructive pulmonary disease, ischemic heart disease, ischemic stroke, cirrhosis of the liver, falls, osteoarthritis, motorized vehicle with three or more wheels, and self-harm. The results reported here identify key health challenges and opportunities for future health interventions and policy changes, and provide information that will help assess the major public health issues in Korea, a nation faced with one of the world's most rapidly ageing populations.

The population attributable fraction of low education for mortality in South Korea with improvement in educational attainment and no improvement in mortality inequalities.

BACKGROUND: The educational attainment of Koreans has greatly increased, which was expected to reduce the magnitude of the population attributable fraction (PAF) of mortality associated with low education levels. However, increase in the relative risk (RR) of mortality among those with lower educational levels actually increased the PAF. The purpose of this study was to examine the change in the PAF of lower educational levels for mortality in Korea, where educational attainment has improved and is associated with the exacerbation of inequalities in mortality levels. METHODS: National census data were used to derive educational levels. The mortality-associated RR of lower educational levels was calculated by reference to national census and death certificate data from 1995, 2000, 2005, and 2010. PAFs were calculated for all-cause mortality, malignant neoplasms, cerebrovascular disease, heart disease, and suicide by gender and age group (30-44 and 45-59 years). RESULTS: The PAF of low educational level in terms of total mortality has decreased since 1995 in both genders. This trend was more prominent among those aged 30-44 years. However, the PAFs of suicide in younger females (30-44 years) and of cerebrovascular disease in older males (45-59 years) have increased. The RRs of all-cause mortality and those of the four leading causes of death in those with the lowest educational levels have increased, especially in females aged 30-44 years. CONCLUSIONS: The consistent and sharp increase in the attainment of education has contributed to the reduction in the PAFs of lower education for mortality, despite the fact that mortality inequalities have not improved. Efforts to reduce health inequalities must promote healthy public policy and address public health policies.

Risks of Lung Cancer due to Radon Exposure among the Regions of Korea.

Radon is likely the second most common cause of lung cancer after smoking. We estimated the lung cancer risk due to radon using common risk models. Based on national radon survey data, we estimated the population-attributable fraction (PAF) and the number of lung cancer deaths attributable to radon. The exposure-age duration (EAD) and exposure-age concentration (EAC) models were used. The regional average indoor radon concentration was 37.5 95 Bq/m(3). The PAF for lung cancer was 8.3% (European Pooling Study model), 13.5% in males and 20.4% in females by EAD model, and 19.5% in males and 28.2% in females by EAC model. Due to differences in smoking by gender, the PAF of radon-induced lung cancer deaths was higher in females. In the Republic of Korea, the risk of radon is not widely recognized. Thus, information about radon health risks is important and efforts are needed to decrease the associated health problems.

Employment status and mortality among Korean men over a 13-year period.

OBJECTIVES: This study explored the effect of employment status on mortality over a 13-year period in Korean men. METHODS: Data were used from the Korean Labor and Income Panel Study from 1999 to 2012. This study started with 2,737 subjects and included employed men in good health, aged 30-69 years. Deaths were tracked for 13 years from 2000 to 2012. Employment status classifications were: (1) regular employees, (2) precarious employees, (3) petty bourgeoisie, and (4) employers. Hazard ratios (HRs) were calculated using a Cox proportional hazards model, and were adjusted for age, education, income, and occupation, with regular employees as the reference category. To examine the effect of employment status and include employment history, the risk ratios of mortality were measured using the Poisson regression model, considering the duration of each employment and using 0 years as the reference category. RESULTS: Over the course of the 13-year study, being a precarious employee (HR, 1.84) or petty bourgeoisie (HR, 1.87) at a particular point in time had a negative effect on mortality when compared with regular employees. Furthermore, working as precarious employees or petty bourgeoisie had no positive effect on mortality. A positive effect was observed, however, on the overall mortality risk for regular employees. CONCLUSIONS: These results suggest that a healthy social policy is needed for precarious employees and petty bourgeoisie to avoid disadvantages in the workplace and the social safety net.

Pulmonary Tuberculosis is Associated with Elevated Risk of Lung cancer in Korea: The Nationwide Cohort Study.

Objective: Although previous studies suggest that previous pulmonary tuberculosis was associated with increased risk of lung cancer. It remains controversial whether pulmonary tuberculosis is a risk factor for lung cancer. Our study was aimed to examine the association between pulmonary tuberculosis and lung cancer risk in Korean. Methods: The Korean National Health and Nutrition Examination Survey database was linked with the Korean National Cancer Incidence Database to examine the occurrence of pulmonary tuberculosis and lung cancer. The linked databases were also merged with causes of death database of Statistics Korea. The Cox-proportional hazards model was used to estimates the hazard risk of lung cancer for Korean adults aged ≥40 years with pulmonary tuberculosis. Results: Of 20,252 total participants, 2,640 (13.0%) had old pulmonary tuberculosis (a medical history of pulmonary tuberculosis or radiologically inactive tuberculosis). After adjusting for all covariates, the hazard ratio of lung cancer among patients with old pulmonary tuberculosis was 3.24 (95% CI, 1.87‒5.62) compared to the control group. According to smoking status, the hazard ratios of lung cancer for never smokers, ex-smokers, and current smokers among participants with old pulmonary tuberculosis were 3.52 (95% CI, 1.17‒10.63), 2.16 (95% CI, 0.89‒5.24), and 3.71 (95% CI, 1.49‒9.22) compared to the control group, respectively. Conclusions: Korean adults with old pulmonary tuberculosis have a higher risk of lung cancer, compared to general population without pulmonary tuberculosis.

A publicly well-accepted measure versus an academically desirable measure of health inequality: cross-sectional comparison of the difference between income quintiles with the slope index of inequality.

OBJECTIVES: The difference between income quintiles in health is relatively well accepted by the general public as a measure of health inequality. However, the slope index of inequality (SII) in health reflects the patterns of all social groups, including the middle 60%, and it could therefore be considered more academically desirable. If these two measures are closely correlated, the widespread use of the difference between income quintiles in health would be better supported. This study was conducted to compare differences between income quintiles in life expectancy (LE) and healthy life expectancy (HLE) with the SII. DESIGN: Cross-sectional comparison using correlational analysis of district level income differences in LE and HLE with associated SII. SETTING: All 252 subnational districts of Korea. PARTICIPANTS: A total of 342 439 895 subjects (171 287 729 men, 171 152 166 women) and 1 753 476 deaths (970 928 men, 782 548 women) between 2008 and 2014 were analysed. PRIMARY AND SECONDARY OUTCOME MEASURES: Difference in LE and HLE by income quintile and associated SII. RESULTS: The Pearson correlation coefficients between differences between income quintiles and the SII were generally high: 0.97 (95% CI 0.96 to 0.98) for LE in men and women combined and 0.96 (95% CI 0.94 to 0.97) for HLE in men and women combined. In most districts, the SII was greater than the difference between income quintiles. CONCLUSION: Differences between income quintiles were closely correlated with the SII. The widespread use of differences between income quintiles in health as a measure of health inequality may be preferable for communicating results of health inequality measurements to the public.

Trends in inequality in life expectancy at birth between 2004 and 2017 and projections for 2030 in Korea: multiyear cross-sectional differences by income from national health insurance data.

OBJECTIVES: The current status, time trends and future projections of a national health equity target are crucial elements of national health equity surveillance. This study examined time trends in inequality by income in life expectancy (LE) at birth between 2004 and 2017 and made future projections for the year 2030 in Korea. DESIGN: Using individually linked mortality data, time trends in inequality by income in LE at birth were examined. The LE projection was made with the Lee-Carter model. SETTING: Total Korean population and death data derived from the National Health Information Database of the National Health Insurance Service. PARTICIPANTS: A total of 685 773 157 subjects and 3 486 893 deaths between 2004 and 2017 were analysed. PRIMARY AND SECONDARY OUTCOME MEASURES: Annual LE and the magnitude of inequality by income in LE between 2004 and 2030. RESULTS: Inequality by income in LE among the total Korean population increased during the past 14 years, and this inequality is projected to become even greater in the future. In 2030, the magnitude of inequality by income in LE is projected to increase by 0.25 years in comparison to the magnitude in 2017. The increase in LE inequality was projected to be more prominent among women, with a projected 1.08 year increase in LE inequality between 2017 and 2030. CONCLUSION: Aggressive policies should be developed to close the increasing LE gap in Korea. LE inequalities by income should be considered as a measurable target for health equity in the process of establishing the National Health Plan 2030 in Korea.

Mediating effects of metabolic factors on the association between fruit or vegetable intake and cardiovascular disease: the Korean National Health and Nutrition Examination Survey.

OBJECTIVE: We assessed the mediating effects of metabolic components on the relationship between fruit or vegetable intake and cardiovascular disease (CVD). DESIGN: Cross-sectional study. SETTING: This study was conducted using data from the 2013-2015 Korean National Health and Nutrition Examination Survey, which is a national representative cross-sectional survey to assess health and nutritional status in the Korean population. METHOD AND ANALYSIS: A total of 9040 subjects (3555 males and 5485 females) aged ≥25 years were included in the study. Physician-diagnosed CVD via self-report was used as the outcome. Fruit or vegetable intake was measured via a dish-based semiquantitative food frequency questionnaire and grouped into categories (<1 time/day, 1 time/day, 2 times/day and ≥3 times/day). Systolic blood pressure (SBP), cholesterol and fasting glucose were considered metabolic mediators, and the bootstrap method was used to assess mediating effect. RESULTS: About 1.8% of adults aged 25-64 years had CVD. According to the result of 'process' macro, the confounder-adjusted risk for CVD decreased by 14% (OR=0.86, 95% CI 0.74 to 0.98) as fruit, but not vegetable, intake was increased by one unit per day. After additional adjustment for three metabolic factors simultaneously, the OR was attenuated to 0.89 (95% CI 0.77 to 1.03). This result indicates that the indirect effect of three metabolic factors accounted for 21.4% of the relationship between fruit intake and CVD. SBP was a more important metabolic mediator than the other factors. The indirect effect by metabolic factors accounted for 30.0% when body mass index was additionally controlled as a mediator, and SBP still had an independent effect compared with the other mediators. CONCLUSIONS: Our results indicate that controlling SBP may lessen the CVD risk, and a diet rich in fruits can regulate SBP which, in turn, reduces CVD risk.

The 2017 Korean National Growth Charts for children and adolescents: development, improvement, and prospects.

Growth charts are curves or tables that facilitate the visualization of anthropometric parameters, and are widely used as an important indicator when evaluating the growth status of children and adolescents. The latest version of the Korean National Growth Charts released in 2007 has raised concerns regarding the inclusion of data from both breastfed and formula-fed infants, higher body mass index (BMI) values in boys, and smaller 3rd percentile values in height-for-age charts. Thus, new growth charts have been developed to improve the previous version. The 2006 World Health Organization Child Growth Standards, regarded as the standard for breastfed infants and children, were introduced for children aged 0-35 months. For children and adolescents aged 3-18 years, these new growth charts include height-for-age, weight-for-age, BMI-for-age, weight-for-height, and head circumference-for-age charts, and were developed using data obtained in 1997 and 2005. Data sets and exclusion criteria were applied differently for the development of the different growth charts. BMI-for-age charts were adjusted to decrease the 95th percentile values of BMI. Criteria for obesity were simplified and defined as a BMI of ≥95th percentile for age and sex. The 3rd percentile values for height-for-age charts were also increased. Additional percentile lines (1st and 99th) and growth charts with standard deviation lines were introduced. 2017 Korean National Growth Charts are recommended for the evaluation of body size and growth of Korean children and adolescents for use in clinics and the public health sector in Korea.