Age- and cause-specific contributions to income difference in life expectancy at birth: findings from nationally representative data on one million South Koreans

Changes in contributions of age- and cause-specific mortality to the widening life expectancy gap between North and South Korea, 1990-2019: An analysis of the Global Burden of Disease Study 2019

Background

Life expectancy gaps between North and South Korea have increased but contributions to these gaps remain poorly understood. Using data from the Global Burden of Disease Study (GBD) 2019, we examined how much death from specific diseases contributed to these gaps in different age groups over three decades.

Methods

Data for death numbers and population by sex and 5-year age groups in both North and South Korea from 1990 to 2019 were extracted from the GBD 2019 to calculate life expectancy. Joinpoint regression analysis was conducted to investigate changes in life expectancy in North and South Korea. We used decomposition analysis to partition differences in life expectancy within and between the two Koreas into changes in age- and cause-specific death contributions.

Results

Life expectancy increased in two Koreas from 1990 to 2019, but North Korea experienced a marked decline in life expectancy during the mid-1990s. The life expectancy gaps between the two Koreas were greatest in 1999, with a difference of 13.3 years for males and 14.9 years for females. The main contributors to these gaps were higher under-5 mortality from nutritional deficiencies for males (4.62 years) and females (4.57 years) in North Korea, accounting for about 30% of the total gap in life expectancy. After 1999, the life expectancy gaps reduced but persisted with differences of about ten years by 2019. Notably, chronic diseases contributed to about 8 out of 10 years of life expectancy gap between the two Koreas in 2019. Differential cardiovascular disease mortality in the older groups was the main contributor to the life expectancy gap.

Conclusions

The contributors to this gap have shifted from nutritional deficiencies in children younger than five years to cardiovascular disease among elderly people. Efforts for strengthening social and healthcare systems are needed to curb this large gap.

A longitudinal study of the association between visual impairment and income change using a national health screening cohort

We evaluated the influence of visual impairment (VI) on income change using the longitudinal database of a Korean National Health Insurance Service cohort. A total of 5292 participants ≥ 40 years old and registered as visually impaired persons were selected at a 1:4 ratio with 45,081 non-VI participants matched for age, sex, and income level. The income level of both the VI and non-VI groups increased over time. In the VI group, the income levels 3, 4 and 5 years were higher than the initial value, while the income levels from 1 through 5 years were increased each year in the non-VI group. The rate of change in income between time and VI were significant. In the subgroup analysis considering age, sex, and severity of VI, the rate of change in income were significant in < 65 years old subgroups. Regarding the severity of VI, a significant interaction was found for the mild-to-moderate VI subgroup. Although both the VI and non-VI groups showed increased income levels over 5 years, the degree of income increase in the VI group was relatively lower than that in the non-VI group. This finding was prominent in the middle-age subgroup. These results strongly suggested that VI induced an income inequality.

The Association between Herpes Zoster and Increased Cancer Risk: A Nationwide Population-Based Matched Control Study

Background: Herpes zoster (HZ) is strongly associated with decreased immune function, a factor of cancer development. Previous studies suggested inconsistent results regarding the association between HZ and increased cancer risk. We aimed to analyze the association between HZ and specific cancer risk. Methods: Of 134,454 patients diagnosed with HZ between 2002 and 2015, 81,993 HZ patients were matched 1:1 with non-HZ individuals by age, sex, and Charlson comorbidity index. Both groups were examined at 1, 3, and 5 years for cancer diagnosis. A Cox proportional hazard regression model was used to estimate cancer risk in both groups. The postherpetic neuralgia (PHN) and non-HZ groups were compared for specific cancer risk. Results: The HZ group showed a slightly decreased overall cancer risk compared with the non-HZ group (hazard ratio [HR] 0.94, 95% confidence interval [CI] 0.90–0.97, p = 0.002). The HRs for specific cancer risk were 0.41 (95% CI, 0.33–0.50, p < 0.001); 0.86 (95% CI, 0.81–0.91, p < 0.001); 0.87 (95% CI, 0.78–0.97, p = 0.014); 0.80 (95% CI 0.73–0.87, p < 0.001); 1.20 (95% CI, 1.07–1.34, p = 0.001); and 1.66 (95% CI, 1.35–2.03, p < 0.001) for cancers of the lips, mouth, and pharynx; digestive system; respiratory system; unknown secondary and unspecified sites; thyroid and endocrine glands; and lymphoid and hematopoietic systems, respectively. The HZ with PHN group showed higher HR for specific cancer risk, such as lymphoid and hematopoietic systems (95% CI, 1.27–2.39, p < 0.001). Conclusion: HZ was associated with increased or decreased incidence of specific cancers. PHN further increased the risk of developing certain cancers in HZ patients.

Income differences in screening, incidence, postoperative complications, and mortality of thyroid cancer in South Korea: a national population-based time trend study

Background

The incidence of thyroid cancer (TC) has increased rapidly over the past few decades in Korea. This study investigated whether the TC epidemic has been driven by overdiagnosis.

Methods

We calculated the TC screening rate from mid-2008 through mid-2014, and the incidence, postoperative complication, and mortality rates of TC between 2006 and 2015, using data from the Korea Community Health Survey, the National Health Insurance Database, and the cause-of-death data of Statistics Korea. Trends in age-standardized rates of all indicators were examined, along with income gaps therein. Analyses were conducted for lung cancer and stroke as negative control outcomes.

Results

The incidence rate of TC increased from 46.6 per 100,000 to 115.0 per 100,000 between 2006 and 2012, and then decreased to 63.5 per 100,000 in 2015. Despite these remarkable changes in incidence, mortality did not fluctuate during the same period. High income was associated with high rates of screening, incidence, and postoperative complications, while low income showed an association with a high mortality rate. Analyses using negative control outcomes showed that high income was associated with low rates of both incidence and mortality, which contrasted with the patterns of TC. The recent decreases in TC incidence and postoperative complications, which reflect societal concerns about the overdiagnosis of TC, were more pronounced in high-income individuals than in low-income individuals.

Conclusions

The time trends in income gaps in screening, incidence, postoperative complications, and mortality of TC, as well as negative control outcomes, provided corroborating evidence of TC overdiagnosis in Korea.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07597-4.

Age- and cause-specific contributions to the life expectancy gap between Medical Aid recipients and National Health Insurance beneficiaries in Korea, 2008-2017

Recipients of Medical Aid, a government-funded social assistance program for the poor, have a shorter life expectancy than National Health Insurance beneficiaries in Korea. This study aims to explore the contributions of age and major causes of death to the life expectancy difference between the two groups. We used the National Health Information Database provided by the National Health Insurance Service individually linked to mortality registration data of Statistics Korea between 2008 and 2017. Annual abridged life tables were constructed and Arriaga’s life expectancy decomposition method was employed to estimate age- and cause-specific contributions to the life expectancy gap between National Health Insurance beneficiaries and Medical Aid recipients. The life expectancy difference between National Health Insurance beneficiaries and Medical Aid recipients was 14.5 years during the period of 2008–2017. The age groups between 30 and 64 years accounted for 78.7% and 67.5% of the total life expectancy gap in men and women, respectively. Cancer was the leading cause of death contributing to excess mortality among Medical Aid recipients compared to National Health Insurance beneficiaries. More specifically, alcohol-attributable deaths (such as alcoholic liver disease, liver cancer, liver cirrhosis, and alcohol/substance abuse), suicide, and cardiometabolic risk factor–related deaths (such as cerebrovascular disease, ischemic heart disease, and diabetes) were the leading contributors to the life expectancy gap. To decrease excess deaths in Medical Aid recipients and reduce health inequalities, effective policies for tobacco and alcohol regulation, suicide prevention, and interventions to address cardiometabolic risk factors are needed.

Inequality in Life Expectancy in Korea according to Various Categorizations of the National Health Insurance Premiums as a Marker of Income

The purpose of this study was to examine the degree to which the magnitude of income inequality in life expectancy according to different categorization across beneficiary types under the National Health Insurance Service (NHIS) in Korea. We used population and death data in 2017 from the National Health Information Database of the NHIS. Income quintile groups were classified in four ways according to beneficiary type (employee insured, self-employed insured, and Medical Aid beneficiaries). Standard life table procedures were used to calculate life expectancy. The life expectancy gap between the lowest and highest income quintiles was the largest when the entire population was divided into quintiles without distinguishing among types of beneficiaries. In conclusion, we suggest that income quintile indicators in NHIS data, measured without distinguishing among types of beneficiaries, may best represent the magnitude of health inequalities in Korean society. This indicator could be used for future research on health inequalities, as well as for monitoring health inequalities in Korea.

What has contributed to the large sex differentials in lifespan variation and life expectancy in South Korea?

To date, research on sex differentials in lifespan variation and life expectancy has mainly been conducted in Western countries and there is a dearth of data from South Korea. This study aimed to further the understanding of mortality transition and life expectancy in South Korea, and the associated trajectories of age-at-death variation, through an analysis of life disparity by gender. Using complete life tables for South Korea for 1970-2015, sex differentials (female-male differences) in life disparity and life expectancy at birth were estimated, and sex differentials in life expectancy were decomposed by age and cause of death. The results showed that sex differentials in life expectancy at birth have not reduced significantly in the last 45 years (1970: 7.1 years; 2015: 6.2 years). Life disparity has reduced more rapidly for females than males, and the difference increased from -0.1 year in 1981 to -1.6 years in 2015. Sex differentials in life expectancy and life disparity in South Korea were higher during 1970-2015 than in several Western countries with high life expectancy. The elderly age group (60 and above) contributed 50% of the total sex difference in life expectancy at birth in 1970, and this increased to 70% in 2015. The contribution of the age group 15-59 years reduced significantly over the period. Decomposition of life expectancy at birth by cause revealed that diseases of the circulatory system (2.2 years), followed by external causes (1.3 years), were the most important causes of the sex differences in life expectancy at birth in 1983, and in 2015 neoplasms (2.2 years) and external causes (1.1 years) explained half of the total sex differences. There has been a significant shift in the age-specific pattern of the contribution towards each cause of death. Overall, sex differentials in life disparity and life expectancy at birth have remained significant in South Korea in the last 45 years.

Life expectancy and inequalities therein by income from 2016 to 2018 across the 253 electoral constituencies of the National Assembly of the Republic of Korea

OBJECTIVE

We calculated life expectancy and inequalities therein by income for the period of 2016-2018 across the 253 electoral constituencies of the 20th National Assembly election in Korea.

METHODS

We obtained population and death data between 2016 and 2018 from the National Health Information Database and constructed abridged life tables using standard life table procedures according to sex and income quintiles for the electoral constituencies of the 20th National Assembly election held in 2016.

RESULTS

Life expectancy across the 253 constituencies ranged from 80.51 to 87.05 years, corresponding to a gap of 6.54 years. The life expectancy difference by income across the 253 constituencies ranged from 2.94 years to 10.67 years. In each province, the difference in life expectancy by income across electoral constituencies was generally greater than the inter-constituency differences. Constituencies in capital and metropolitan areas showed a higher life expectancy and a lower life expectancy difference by income than constituencies in rural areas.

CONCLUSIONS

Pro-rich inequalities in life expectancy by income existed in every electoral constituency in Korea. Both intra-constituency and inter-constituency socioeconomic inequalities in health should be highlighted in future policy-making in the National Assembly.

Regional Variation of Hospitalization Rates for Asthma in Korea: Association with Ambient Carbon Monoxide and Health Care Supply

This study was performed to investigate the relationship between the hospitalization rate for asthma and the ambient carbon monoxide (CO) by examining regional variation of the hospitalization rates for asthma in Korea and its factors. The hospital inpatient claims for asthma were acquired from the National Health Insurance database in 2015. A multivariate linear regression was performed with the hospitalization rate for asthma as a dependent variable. The annual ambient concentration of CO showed a negative association with the hospitalization rates for asthma while that of sulfur dioxide showed a positive association. The number of primary care physicians showed a negative association with the hospitalization rates for asthma while the number of beds in hospitals with less than 300 beds showed a positive association. The negative association of the ambient concentration of CO with the hospitalization rates for asthma showed results upon further investigation.

Factors associated with the suicide rates in Korea

The suicide rate in the Republic of Korea remains among the highest in the world, which needs to be examined in various aspects. This study investigated factors associated with the suicide rates in Korea. The suicide rates of 251 districts in Korea in 2015 and their relationships with the prevalence of heavy drinking, health care provision, and religion as well as demographic characteristics were examined with a Pearson correlations and a multiple linear regression analysis. The suicide rate in Korea was 26.5 per 100,000 persons in 2015. The regression analysis showed that the income level of the region, as represented by the average national health insurance premium, had a negative association with the suicide rate and that the prevalence of heavy drinking and the percentage of the population aged 65 and above had positive associations with the suicide rate. While the unemployment rate and the proportion of Catholics showed negative relationships with the suicide rate in the correlation matrix, the association was statistically insignificant in the regression analysis. Special attention should be given to excessive drinking and socio-economically disadvantaged conditions in taking measures to prevent suicide.

Trends in life expectancy among medical aid beneficiaries and National Health Insurance beneficiaries in Korea between 2004 and 2017

BACKGROUND

Medical Aid beneficiaries in Korea are more likely to have poor health status and to receive insufficient healthcare services, but their life expectancy has not been compared with that of National Health Insurance beneficiaries.

METHODS

We used the National Health Information Database in Korea to obtain aggregate data on the numbers of population and deaths according to calendar year (2004 to 2017), sex, age group, and insurance eligibility (Medical Aid or National Health Insurance). Between 2004 and 2017, a summed total of 697,503,634 subjects (combining numbers of subjects for 14 years) and 3,536,778 deaths, including 22,417,216 Medical Aid beneficiaries and 499,604 associated deaths, were used to construct annual abridged life tables.

RESULTS

In 2017, the life expectancy of Medical Aid beneficiaries was 70.9 years, while that of National Health Insurance beneficiaries was 83.7 years. Between 2004 and 2017, life expectancy for Medical Aid beneficiaries increased by 8.7 years in men and 6.1 years in women, while life expectancy for National Health Insurance beneficiaries increased by 5.2 years in men and 4.5 years in women. The life expectancy difference between National Health Insurance beneficiaries and Medical Aid beneficiaries was especially great among men across all study periods. The life expectancy difference was 15.8 years for men and 8.9 years for women in 2017.

CONCLUSIONS

The life expectancy of Medical Aid beneficiaries was shorter than that of National Health Insurance beneficiaries. The government should implement policies to deliver more adequate health care to Medical Aid beneficiaries.

The Life Expectancy Gap between Registered Disabled and Non-Disabled People in Korea from 2004 to 2017

This study aimed to estimate and compare life expectancy at birth among people with and without officially registered disabilities in Korea between 2004 and 2017. We used the National Health Information Database in Korea to obtain aggregate data on the numbers of population and deaths according to calendar year (2004 to 2017), sex, age groups, and officially registered disability status. A total of 697,503,634 subjects and 3,536,778 deaths, including 33,221,916 disabled subjects (829,464 associated deaths), were used to construct life tables. Between 2004 and 2017, life expectancy for people with disabilities increased by 9.1 years in men and 8.3 years in women, while life expectancy for the non-disabled increased by 5.5 years in men and 4.6 years in women. The average life expectancy difference between non-disabled and disabled people was 18.2 years during the study period, decreasing from 20.4 years in 2004 to 16.4 years in 2017. In 2017, the life expectancy of people with the most severe grade of disabilities was 49.7 years, while the life expectancy of people with the least severe grade of disabilities was 77.7 years. The government should implement more effective policies to protect the health of people with officially registered disabilities.

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.

Factors Affecting Activity Limitation in the Elderly: Data Processed from the Korea National Health and Nutrition Examination Survey, 2016

Objectives

The aim of this study was to compare the sociodemographic characteristics, depression, and the health-related quality of life outcome, among the Korean elderly population, with and without activity limitation.

Methods

The data used was drawn from the raw data of the seventh Korea National Health and Nutrition Examination Survey (N = 8,150). There were 1,632 records for individuals aged 65 or older extracted from the seventh Korea National Health and Nutrition Examination Survey database, 199 of those had missing responses (n = 1,433). Differences within the sociodemographic characteristic, the Patient Health Questionnaire-9, and the EuroQol-5 Dimension were analyzed using logistic regression analysis according to the presence or absence of activity limitation.

Results

The prevalence of activity limitation among the elderly individuals surveyed was 19.9%. In the unadjusted regression analysis, the odds ratios of all independent variables (age, gender, education level, type of region, family income, the Patient Health Questionnaire-9, all 5 domains of the EuroQol-5 Dimension) between the elderly individuals with and without activity limitation, were significant. Although, in the adjusted logistic regression analysis, it was observed that the only factors that were significantly associated with activity limitation were the Patient Health Questionnaire-9, EuroQol-5 Dimension, type of region, and family income.

Conclusion

These findings demonstrated that activity limitation in elderly individuals is associated with the sociodemographic characteristics of family income and type of region of residence, as well as depression and the health-related quality of life outcome.

Why is Life Expectancy in Busan Shorter than in Seoul? Age and Cause-Specific Contributions to the Difference in Life Expectancy between Two Cities

PURPOSE

Seoul and Busan are the two largest cities in Korea. However, life expectancy (LE) in Busan is shorter than in Seoul and among the total Korean population. This study was conducted to decompose age- and cause-specific contributions to the LE difference between Seoul and Busan.

MATERIALS AND METHODS

We obtained population and mortality data for Seoul and Busan between 2015 and 2017 from Statistics Korea. We applied Arriaga's decomposition method to life table data to estimate age- and cause-specific contributions to the LE difference between Seoul and Busan.

RESULTS

During 2015-2017, LE in Busan was shorter than in Seoul by 2.22 years. Roughly two-thirds of the LE gap between Seoul and Busan was due to excess mortality among elderly people in Busan. The ≥85 age group alone contributed to approximately 20% of the LE gap, while no meaningful contribution was made by the 1-24 age groups. Cardiovascular disease accounted for over 40% of the total LE gap between Seoul and Busan, and this factor was more prominent in women. The top 15 leading specific causes of deaths explained nearly the entire LE difference between Seoul and Busan.

CONCLUSION

The difference in LE between Seoul and Busan was due to higher mortality rate in Busan than in Seoul, especially in the elderly population and from cardiovascular diseases. Information on age- and cause-specific contributions to the LE difference between Seoul and Busan may guide health policy-makers to plan strategies for reducing the gap in LE.

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.

Objective and subjective financial status and mortality among older adults in China

The association between financial status and mortality in older adults is well documented. However, it is unclear whether the association may vary by objective and subjective indicators of financial status. To examine this issue, we used the latest four waves (2005, 2008/2009, 2011/2012, and 2014) of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) of community-residing adults aged 65 and older (n = 25,954). Financial status was assessed using eight objective, subjective, and culturally-oriented measures to capture various dimensions of financial resources at older ages. Multivariate hazard models were used to examine how different indicators of financial status were associated with subsequent mortality in all older adults and by age, gender, and urban-rural residence. Results showed that higher financial status-either objective or subjective-was associated with lower risks of mortality. Subjective assessments of financial status had stronger associations with mortality than objective assessments. The patterns were generally similar between young-old (aged 65-79) and the oldest-old (aged 80+), between women and men, and between rural and urban areas. Together, the findings offer new evidence to help improve the socioeconomic gradient in mortality among older adults in China.

Do Reduced Copayments Affect Mortality after Surgery due to Stroke? An Interrupted Time Series Analysis of a National Cohort Sampled in 2003-2012

BACKGROUND

The South Korean government introduced a policy in 2 phases, in September 2005 and in January 2010, for reducing copayments for patients with critical diseases, including stroke, to prevent excessive medical expenditures and to ease economic barriers. Previous studies of the effect of this policy were focused primarily on cancer. Therefore, we investigated the relationship between this policy and 1-year mortality after surgery among patients with stroke.

METHODS

We used data from the Korean National Health Insurance sampling cohort (n = 2173 in 2003-2012) and performed an interrupted time series analysis.

RESULTS

Approximately 26% of the patients died within 1 year after surgery. The time trends after reducing copayments from 10% to 5% (phase 2) were inversely associated with risk of 1-year mortality (relative risk = .855, 95% confidence interval: .749-.975; P = .0196). In addition, this inverse association was greater in patients with low incomes, of older ages, and with higher Charlson comorbidity indices.

CONCLUSIONS

The introduction of a policy for reducing copayments to ease excessive cost burdens for patients with stroke was positively associated with a reduced risk of 1-year mortality after surgical treatment due to stroke. On the basis of our results, health policy makers should make an effort to identify vulnerable populations and to overcome economic barriers for providing effective alternatives to ensure patients receive optimal health care.

Comparison of District-level Smoking Prevalence and Their Income Gaps from Two National Databases: the National Health Screening Database and the Community Health Survey in Korea, 2009-2014

BACKGROUND

We compared age-standardized prevalence of cigarette smoking and their income gaps at the district-level in Korea using the National Health Screening Database (NHSD) and the Community Health Survey (CHS).

METHODS

Between 2009 and 2014, 39,049,485 subjects participating in the NHSD and 989,292 participants in the CHS were analyzed. The age-standardized prevalence of smoking and their interquintile income differences were calculated for 245 districts of Korea. We examined between-period correlations for the age-standardized smoking prevalence at the district-level and investigated the district-level differences in smoking prevalence and income gaps between the two databases.

RESULTS

The between-period correlation coefficients of smoking prevalence for both genders were 0.92-0.97 in NHSD and 0.58-0.69 in CHS, respectively. When using NHSD, we found significant income gaps in all districts for men and 244 districts for women. However, when CHS was analyzed, only 167 and 173 districts for men and women, respectively, showed significant income gaps. While correlation coefficients of district-level smoking prevalence from two databases were 0.87 for men and 0.85 for women, a relatively weak correlation between income gaps from the two databases was found.

CONCLUSION

Based on two databases, income gaps in smoking prevalence were evident for nearly all districts of Korea. Because of the large sample size for each district, NHSD may provide stable district-level smoking prevalence and its income gap and thus should be considered as a valuable data source for monitoring district-level smoking prevalence and its socioeconomic inequality.

Prevalence of Overweight and Income Gaps in 245 Districts of Korea: Comparison Using the National Health Screening Database and the Community Health Survey, 2009-2014

BACKGROUND

We compared age-standardized overweight prevalence and their income gaps at the level of district in Korea using the National Health Screening Database (NHSD) and the Community Health Survey (CHS).

METHODS

We analyzed 39,093,653 subjects in the NHSD and 926,580 individuals in the CHS between 2009 and 2014. For the comparison of body mass index (BMI) distributions, data from 26,100 subjects in the Korea National Health and Nutrition Examination Survey (KNHANES) were also analyzed. We calculated the age-standardized overweight prevalence and its interquintile income gap at the district level. We examined the magnitudes of the between-period correlation for age-standardized overweight prevalence. The differences in overweight prevalence and its income gap between the NHSD and the CHS were also investigated.

RESULTS

The age-adjusted mean BMI from the CHS was lower than those from the NHSD and the KNHANES. The magnitudes of the between-period correlation for overweight prevalence were greater in the NHSD compared to the CHS. We found that the district-level overweight prevalence in the NHSD were higher in all districts of Korea than in the CHS. The correlation coefficients for income gaps in overweight prevalence between the two databases were relatively low. In addition, when using the NHSD, the district-level income inequalities in overweight were clearer especially among women than the inequalities using the CHS.

CONCLUSION

The relatively large sample size for each district and measured anthropometric data in the NHSD are more likely to contribute to valid and reliable measurement of overweight inequality at the district level in Korea.

Using the National Health Information Database of the National Health Insurance Service in Korea for Monitoring Mortality and Life Expectancy at National and Local Levels

This study explores whether the National Health Information Database (NHID) can be used to monitor health status of entire population in Korea. We calculated the crude mortality rate and life expectancy (LE) at birth across the national, provincial, and municipal levels using the NHID eligibility database from 2004 to 2015, and compared the results with the corresponding values obtained from the Korean Statistical Information Service (KOSIS) of Statistics Korea. The study results showed that the ratio of crude mortality rate between the two data was 0.99. The absolute difference between the LE of the two data was not more than 0.5 years, and did not exceed 0.3 years in gender specific results. The concordance correlation coefficients (CCC) between the crude mortality rates from NHID and the rates from KOSIS ranged 0.997-0.999 among the municipalities. For LE, the CCC between the NHID and KOSIS across the municipalities were 0.990 in 2004-2009 and 0.985 in 2010-2015 among men, and 0.952 in 2004-2009 and 0.914 in 2010-2015 among women, respectively. Overall, the NHID was a good source for monitoring mortality and LE across national, provincial, and municipal levels with the population representativeness of entire Korean population. The results of this study indicate that NHID may well contribute to the national health promotion policy as a part of the health and health equity monitoring system.

Future life expectancy in 35 industrialised countries: projections with a Bayesian model ensemble

BACKGROUND

Projections of future mortality and life expectancy are needed to plan for health and social services and pensions. Our aim was to forecast national age-specific mortality and life expectancy using an approach that takes into account the uncertainty related to the choice of forecasting model.

METHODS

We developed an ensemble of 21 forecasting models, all of which probabilistically contributed towards the final projections. We applied this approach to project age-specific mortality to 2030 in 35 industrialised countries with high-quality vital statistics data. We used age-specific death rates to calculate life expectancy at birth and at age 65 years, and probability of dying before age 70 years, with life table methods.

FINDINGS

Life expectancy is projected to increase in all 35 countries with a probability of at least 65% for women and 85% for men. There is a 90% probability that life expectancy at birth among South Korean women in 2030 will be higher than 86·7 years, the same as the highest worldwide life expectancy in 2012, and a 57% probability that it will be higher than 90 years. Projected female life expectancy in South Korea is followed by those in France, Spain, and Japan. There is a greater than 95% probability that life expectancy at birth among men in South Korea, Australia, and Switzerland will surpass 80 years in 2030, and a greater than 27% probability that it will surpass 85 years. Of the countries studied, the USA, Japan, Sweden, Greece, Macedonia, and Serbia have some of the lowest projected life expectancy gains for both men and women. The female life expectancy advantage over men is likely to shrink by 2030 in every country except Mexico, where female life expectancy is predicted to increase more than male life expectancy, and in Chile, France, and Greece where the two sexes will see similar gains. More than half of the projected gains in life expectancy at birth in women will be due to enhanced longevity above age 65 years.

INTERPRETATION

There is more than a 50% probability that by 2030, national female life expectancy will break the 90 year barrier, a level that was deemed unattainable by some at the turn of the 21st century. Our projections show continued increases in longevity, and the need for careful planning for health and social services and pensions.

FUNDING

UK Medical Research Council and US Environmental Protection Agency.

Suicide rates across income levels: Retrospective cohort data on 1 million participants collected between 2003 and 2013 in South Korea

Background

The relation of income and socioeconomic status with suicide rates remains unclear. Most previous studies have focused on the relationship between suicide rates and macroeconomic factors (e.g., economic growth rate). Therefore, we aimed to identify the relationship between individuals' socioeconomic position and suicide risk.

Methods

We analyzed suicide mortality rates across socioeconomic positions to identify potential trends using observational data on suicide mortality collected between January 2003 and December 2013 from 1,025,340 national health insurance enrollees. We followed the subjects for 123.5 months on average. Socioeconomic position was estimated using insurance premium levels. To examine the hazard ratios of suicide mortality in various socioeconomic positions, we used Cox proportional hazard models.

Results

We found that the hazard ratios of suicide showed an increasing trend as socioeconomic position decreased. After adjusting for gender, age, geographic location, and disability level, Medicaid recipients had the highest suicide hazard ratio (2.28; 95% CI, 1.87–2.77). Among the Medicaid recipients, men had higher hazard ratios than women (2.79; 95% CI, 2.17–3.59 vs. 1.71; 95% CI, 1.25–2.34). Hazard ratios also varied across age groups. The highest hazard ratio was found in the 40–59-year-old group (3.19; 95% CI, 2.31–4.43), whereas the lowest ratio was found in those 60 years and older (1.44; 95% CI, 1.09–1.87).

Conclusions

Our results illuminate the relationship between socioeconomic position and suicide rates and can be used to design and implement future policies on suicide prevention.

•

Suicide showed an increasing trend as income levels decreased.

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Suicide was most frequent in Medicaid recipients.

•

Suicide showed different trends across gender and age groups.

Forty years of economic growth and plummeting mortality: the mortality experience of the poorly educated in South Korea

BACKGROUND

South Korea has experienced rapid economic development and a substantial increase in life expectancy in an extremely short period. Whether this rapid development has been able to adequately address inequalities in health in South Korea may have important policy implications. This paper explores long-term trends in inequalities in mortality related to education in South Korea between 1970 and 2010.

METHODS

We used secondary data on population size and deaths in 1970 and 1980 from a previously published study, and census and death certificate data from Statistics Korea from 1990, 1995, 2000, 2005 and 2010. Trends in age-standardised mortality rates for men and women aged 25-64 according to education, as well as the rate ratio (RR), rate difference (RD), relative index of inequality (RII) and slope index of inequality (SII), were examined over the period 1970-2010.

RESULTS

Despite overall mortality declines of 70-80% in the past 4 decades, educational inequalities have increased or been stagnant. There was minimal decline in mortality since 1970 in South Koreans with only a primary or lower level of education. The RR and RD between tertiary education and primary or lower education increased over the study period, while the RII and the SII in both genders remained stable.

CONCLUSIONS

The South Korean experience over the past 40 years suggests that plummeting mortality rates and huge advances in education at the population level do not translate into reduced educational inequalities in mortality.

Validation of the Korean Genome Epidemiology Study Risk Score to Predict Incident Hypertension in a Large Nationwide Korean Cohort

BACKGROUND

This study aimed to validate the Korean Genome Epidemiology Study (KoGES) risk score to predict the 4-year risk of hypertension (HT) in a large nationwide sample, and compare its discrimination and calibration with the Framingham and blood pressure (BP)-only models.

METHODS AND RESULTS

This study analyzed 69,918 subjects without HT at baseline from the National Sample Cohort in the National Health Insurance Service database. We compared the Framingham, KoGES, and BP-only models for discrimination using area under the receiver-operating characteristic curves (AROC), calibration using goodness-of-fit tests, and reclassification ability using the continuous net reclassification improvement (NRI) and integrated discrimination improvement. Of 69,918 subjects, 18.6% developed HT during the follow-up. AROC was significantly higher for the KoGES (0.733) than for the Framingham (0.729) or BP-only (0.707) model. Recalibrated Framingham model underestimated HT incidence in all deciles (P<0.001). BP-only model overestimated risk in the lower deciles (P<0.001). KoGES model accurately predicted risk in all except the highest decile (χ(2)=14.85, P=0.062). The KoGES model led to a significant improvement in risk reclassification compared with the Framingham and BP-only models (NRI, 0.354; 95% confidence interval [CI], 0.343-0.365 and 0.542; 95% CI, 0.523-0.561, respectively).

CONCLUSIONS

In this validation study, the KoGES model demonstrated better discrimination, calibration, and reclassification ability than either the Framingham or BP-only model. The KoGES model may help identify Korean individuals at high risk for HT. (Circ J 2016; 80: 1578-1582).

Socioeconomic Inequality in mortality using 12-year follow-up data from nationally representative surveys in South Korea

Background

Investigations into socioeconomic inequalities in mortality have rarely used long-term mortality follow-up data from nationally representative samples in Asian countries. A limited subset of indicators for socioeconomic position was employed in prior studies on socioeconomic inequalities in mortality. We examined socioeconomic inequalities in mortality using follow-up 12-year mortality data from nationally representative samples of South Koreans.

Methods

A total of 10,137 individuals who took part in the 1998 and 2001 Korea National Health and Nutrition Examination Surveys were linked to mortality data from Statistics Korea. Of those individuals, 1,219 (12.1 %) had died as of December 2012. Cox proportional hazard models were used to estimate the relative risks of mortality according to a wide range of socioeconomic position (SEP) indicators after taking into account primary sampling units, stratification, and sample weights.

Results

Our analysis showed strong evidence that individuals with disadvantaged SEP indicators had greater all-cause mortality risks than their counterparts. The magnitude of the association varied according to gender, age group, and specific SEP indicators. Cause-specific analyses using equivalized income quintiles showed that the magnitude of mortality inequalities tended to be greater for cardiovascular disease and external causes than for cancer.

Conclusion

Inequalities in mortality exist in every aspect of SEP indicators, both genders, and age groups, and four broad causes of deaths. The South Korean economic development, previously described as effective in both economic growth and relatively equitable income distribution, should be scrutinized regarding its impact on socioeconomic mortality inequalities. Policy measures to reduce inequalities in mortality should be implemented in South Korea.

Electronic supplementary material

The online version of this article (doi:10.1186/s12939-016-0341-9) contains supplementary material, which is available to authorized users.