Regional Deprivation Index and Socioeconomic Inequalities Related to Infant Deaths in Korea

A multicriteria vulnerability index for equitable resource allocation in public health funding

SETTING

This paper describes an action research project with the Centre universitaire intégré de santé et de services sociaux - Capitale Nationale (CIUSSS-CN) who identified a need to assess vulnerability in their territories in order to ensure equitable distribution of the Integrated Perinatal and Early Childhood Services (SIPPE) program funds. The objective was to design and validate a multicriteria model to provide a more accurate portrait of vulnerability based on recent social realities.

INTERVENTION

Our multidisciplinary research team of 7 members included experts in analytics, decision aiding, and community and public health. In collaboration with 6 CIUSSS-CN professionals, we co-constructed, during 9 workshops, a multicriteria model to aggregate the multiple dimensions of vulnerability. We used a value-focused thinking approach and applied the method MACBETH assisted by a geographic information system.

OUTCOMES

Criteria, scales, and weights were validated and led to a vulnerability score for each CIUSSS-CN territory. This score provides a more accurate portrait of territorial disparities based on data and the participants' experience. The model was implemented in a dynamic user-friendly tool and serves to support decision-makers in the resource allocation process. Knowledge transfer was conducted during and after the process.

IMPLICATIONS

This multidisciplinary research has served to anchor public health funding in local realities, with an emphasis on equity and stakeholder engagement. Our mixed-method approach integrating qualitative and quantitative data is adaptable to other contexts. Our results can enhance intervention effectiveness and allow for a better response to the needs of the population targeted by the SIPPE program.

Social determinants of health and somatic growth in preterm infants and children with chronic lung disease

OBJECTIVE

Bronchopulmonary dysplasia (BPD), a common complication of prematurity, is associated with impaired lung function and increased morbidity in childhood. These children display heterogeneous somatic growth patterns which may ultimately impact their risk for later respiratory disease. We aim to understand the relationship between socioenvironmental exposures and growth in this population.

METHODS

A retrospective longitudinal cohort study was conducted using participants (n = 616) enrolled in the Johns Hopkins Outpatient BPD Registry. Growth measurements between 0 and 36 months of age were obtained. Somatic growth measurements, both corrected and uncorrected for gestational age, were converted to z-scores using Center for Disease Control and Prevention normative data. Using a participant's residential zip code, we utilized the 2019 Area Deprivation Index (ADI), the Childhood Opportunity Index (COI) 2.0, and neighborhood food insecurity data from the Maryland Food Bank. Linear regression analysis was performed employing individual socioenvironmental measures as independent variables and growth z-scores as dependent variables in univariate analysis. Univariate analysis was repeated adjusting for gestational age, BPD severity, and the presence of a gastrostomy tube (GT).

RESULTS

Of the three measures analyzed, national COI (nCOI) showed a significant association with mean weight z-scores, mean ADI showed some association with mean weight z-scores, and the percentage of a community experiencing food insecurity showed no association with mean weight z-scores. After adjusting for gestational age, BPD severity, and presence of a GT, children living in areas of greater opportunity (higher nCOI values), had significantly lower weight z-scores at 12 months corrected and at 24 and 36 months uncorrected CONCLUSIONS: Our findings suggest that the COI 2.0, a multidimensional measure, captures more facets of an individual's social environment, as compared to the singular nature of a measure of food insecurity. There are several potential explanations for the phenomenon seen, and further understanding of this dynamic is crucial for designing effective interventions and policies to better address inequities in outcomes.

Regional Disparities in the Infant Mortality Rate in Korea Between 2001 and 2021

BACKGROUND

The infant mortality rate (IMR) has been considered an important indicator of the overall public health level. Despite improvements in recent decades, regional inequalities in the IMR have been reported worldwide. However, there are no Korean epidemiological studies on regional disparities in the IMR.

METHODS

We extracted causes of death data from the Statistics Korea through the Korean Statistical Information Service database between 2001 and 2021. The total and regional IMRs were calculated to determine regional disparities. Based on causes of death and using Seoul as a reference, the excess infant deaths and population attributable fractions (PAFs) were calculated for 15 other metropolitan cities and provinces. The average annual percent changes by region from 2001 to 2021 were obtained using a joinpoint regression program. To assess inequities in IMR trends, the rate ratios (RRs) and rate differences (RDs) of the 15 regions were calculated by dividing the study period into period 1 (2001-2007), period 2 (2008-2014), and period 3 (2015-2021).

RESULTS

The overall IMR in Korea was 3.64 per 1,000 live births, and the IMRs in the 14 regions were relatively higher than that in Seoul, with RRs ranging from 1.15 (95% confidence interval [CI], 1.04, 1.27) in Jeju-do to 1.62 (95% CI, 1.54, 1.71) in Daegu, over the total study period. Significant differences in infant deaths by region were observed for all causes of death, with PAFs ranging from 2.2% (95% CI, 1.7, 2.6) in Gyeonggi-do to 38.4% (95% CI, 38.1, 38.6) in Daegu. The leading cause of excess infant deaths was perinatal problems. The IMR disparities in the relative and absolute measures decreased from 1.44 (1.34, 1.54) to 1.21 (1.10, 1.31) for RRs and from 0.79 (0.63, 0.96) to 0.30 (0.15, 0.45) for RDs between periods 1 and 2, followed by an increase from 1.21 (1.10, 1.31) to 1.36 (1.21, 1.53) for RRs and from 0.30 (0.15, 0.45) to 0.51(0.36, 0.67) for RDs between period 2 and 3.

CONCLUSION

Infant death is associated with place of residence and regional gaps have recently widened again in Korea. An in-depth investigation of the causes of regional disparities in infant mortality is required for effective governmental policies to achieve equality in infant health.

Potential pathways of association from green space to smartphone addiction

Green space is increasingly known to improve physical and mental health. Based on these benefits, green space might also be expected to help mitigate related harmful behavioral patterns, such as obsessive Internet use and relevant addictions. In response, we conducted a study on smartphone addiction, a new form of Internet addiction. We carried out a cross-sectional investigation in August 2022. We recruited 1011 smartphone users across China, measured the Normalized Difference Vegetation Index (NDVI) in their residential neighborhoods (in 1, 2, and 3 km buffers), and captured data on smartphone addiction via the Smartphone Addiction Scale - Short version (SAS-SV). Potential mediators between green space and smartphone addiction, including physical activity, stress, and loneliness, were also reported by participants using the Physical Activity Rating Scale-3 (PRS-3), Depression, Anxiety and Stress Scale-21 Items (DASS-21), and 8-items UCLA Loneliness Scale scales (ULS-8). Multiple linear regression was employed to examine the relationships between green space and smartphone addiction. Structural equation modeling was performed to examine the potential pathways between these variables. Unexpectedly, NDVI in 1 km buffers was positively associated with smartphone addiction. By contrast, population density, an indicator of urbanization, was associated with lower levels of smartphone addiction levels in all NDVI buffer sizes. Meanwhile, we found NDVI was strongly associated with population density as well as other indicators of urbanization. Generally, our findings are unexpected and suggest that greenness may serve as an indicator of urbanization at national levels and that urbanization may buffer against smartphone addiction. During the hot summer, green space and indoor facilities may have competitive land uses, so future research should examine whether this association exists in other seasons and scenarios. We also recommend alternative models to systematically evaluate the effects of different components of residential environments.

Exploring the relationship between socioeconomic deprivation index and Alzheimer's disease using summary-level data: From genetic correlation to causality

Patients with Alzheimer's disease (AD) are markedly increasing as population aging and no disease-modifying therapies are currently available for AD. Previous studies suggested a broad link between socioeconomic status and a variety of disorders, including mental illness and cognitive abilities. However, the association between socioeconomic deprivation and AD has been unknown. We here employed Townsend deprivation index (TDI) to explore such relation and found a positive genetic correlation (r̂_g=0.211, P = 8.00 × 10^-4) between the two traits with summary statistics data (N = 455,258 for TDI and N = 455,815 for AD). Then, we performed pleiotropy analysis at both variant and gene levels using a powerful method called PLACO and detected 87 distinct pleiotropic genes. Functional analysis demonstrated these genes were significantly enriched in pancreas, liver, heart, blood, brain, and muscle tissues. Using Mendelian randomization methods, we further found that one genetically predicted standard deviation elevation in TDI could lead to approximately 18.5% (95% confidence intervals 1.6- 38.2%, P = 0.031) increase of AD risk, and that the identified causal association was robust against used MR approaches, horizontal pleiotropy, and instrumental selection. Overall, this study provides deep insight into common genetic components underlying TDI and AD, and further reveals causal connection between them. It is also helpful to develop a more suitable plan for ameliorating inequities, hardship, and disadvantage, with the hope of improving health outcomes among economically disadvantaged people.

[Social inequalities in under-five mortality: a systematic review]

OBJECTIVE

To identify the characteristics of the published studies on social inequalities in under-five mortality, their theoretical perspectives, axes of inequality, methods and results.

METHOD

We carried out a systematic literature review. We consulted four electronic databases and Google Scholar, for studies published between 2010 and 2018.

RESULTS

We analyzed 126 articles. In 62.7%, territory was studied as the axis of inequality, followed by socioeconomic determinants (27.8%). Neonatal, infant and under-five mortality was analyzed as an output in health in 19.0%, 49.2% and 32.3%, respectively. It predominated ecological (62.7%) and longitudinal (50.0%) studies. Significant reductions in mortality rates were found, however, the decline was not homogeneous among subpopulations.

CONCLUSIONS

The literature reports a marked decrease in under-five mortality; however, the gaps between different axes of inequality continue and in some cases they have increased. Gaps varied according to time, place, axis of inequality and type of mortality analyzed.

Age at menarche of adolescent girls and the neighbourhood socioeconomic status of their school area

PURPOSE

To assess the association between abnormal timing of menarche among adolescent girls and neighbourhood socioeconomic status of their school area.

MATERIALS AND METHODS

Our analysis included 187,024 girls aged 15-18 years from the Korea Youth Risk Behaviour Web-Based Survey (KYRBS) from 2007 to 2015. Early and late menarche were defined as menarche before 11 years and no menarche by age 14 years, respectively. The deprivation index values for the areas where the schools were located were used as an indicator of neighbourhood socioeconomic status based on the 2005 national census data. We calculated odds ratios (OR) for early and late menarche using a multinomial logistic regression model. Covariates included body mass index, parental education, single or stepparents, siblings, household wealth, year of birth, survey year, and urbanisation.

RESULTS

Mean age at menarche was 12 years. The overall proportions of early and late menarche were 11.3% and 3.3%, respectively. When divided into four quartile groups based on the socioeconomic deprivation index, 11.3% of girls in the most deprived quartile and 10.6% in the least deprived area showed early menarche. The prevalence of late menarche did not differ across the deprivation index quartiles of school area. Attendance at schools located in highly deprived areas was associated with up to 10% higher risk of early menarche. This positive association was not evident for late menarche.

CONCLUSION

Among contemporary Korean girls, socioeconomic deprivation of the school area was associated with earlier puberty. This finding highlights the potential role of the socioeconomic environment of schools in women's lifetime health.

Area-Level Socioeconomic Inequalities in Intracranial Injury-Related Hospitalization in Korea: A Retrospective Analysis of Data From Korea National Hospital Discharge Survey 2008-2015

BACKGROUND

Although inequality in traumatic brain injury (TBI) by individual socioeconomic status (SES) exists, interventions to modify individual SES are difficult. However, as interventions for area-based SES can affect the individual SES, monitoring or public health intervention can be planned. We analyzed the effect of area-based SES on hospitalization for TBI and revealed yearly inequality trends to provide a basis for health intervention.

METHODS

We included patients who were hospitalized due to intracranial injuries (ICIs) between 2008 and 2015 as a measure of severe TBI with data provided by the Korea National Hospital Discharge Survey. Area-based SES was synthesized using the 2010 census data. We assessed inequalities in ICI-related hospitalization rates using the relative index of inequality and the slope index of inequality for the periods 2008-2009, 2010-2011, 2012-2013, and 2014-2015. We analyzed the trends of these indices for the observation period by age and sex.

RESULTS

The overall relative indices of inequality for each 2-year period were 1.82 (95% confidence interval, 1.5-2.3), 1.97 (1.6-2.5), 2.01 (1.6-2.5), and 2.01 (1.6-2.5), respectively. The overall slope indices of inequality in each period were 38.74 (23.5-54.0), 36.75 (21.7-51.8), 35.65 (20.7-50.6), and 43.11 (27.6-58.6), respectively. The relative indices of inequality showed a linear trend for men (P = 0.006), which was most evident in the ≥ 65-year age group.

CONCLUSION

Inequality in hospitalization for ICIs by area-based SES tended to increase during the observation period. Practical preventive interventions and input in healthcare resources for populations with low area-based SES are likely needed.

Russian subject-level index of multidimensional deprivation and its association with all-cause and infant mortality

Background

Social and environmental inequalities in public health are recognized as global problems of our time. From the point of view of the theory of deprivation, social and environmental determinants identified as deprivation indicators, which help to detect health inequality. Indices are one of the most practical and powerful tools for measuring the level of deprivation.

Objectives

The aims of our study are (1) to develop a Russian derivation index to measure the levels of deprivation and (2) to analyze its associations with total and infant mortality.

Material and methods

Deprivation indicators were obtained from the Federal State Statistics Service of Russia. All mortality data were taken from the official website of the Federal Research Institute for Health Organization and Informatics of Ministry of Health of the Russian Federation from 2009 to 2012. Principal components analysis with varimax rotation was used to (1) select suitable deprivation indicators and (2) create the index. A Spearman's correlation was run to determine the relationship of deprivation with all-cause and infant mortality. Ordinary least squares (OLS) regression was used to assess the relationship between deprivation and infant mortality. Development of the index and statistical analysis were carried out using R and SPSS software.

Results

There is not a statistically significant correlation between deprivation and all-cause mortality. OLS regression showed a significant relationship between deprivation and infant mortality (p = 0.02). For every one-unit increase in the index score, infant mortality rate increases by about 20%.

Analysis of association between low birth weight and socioeconomic deprivation level in Japan: an ecological study using nationwide municipal data

BACKGROUND

Several international studies have indicated an association between socioeconomic deprivation levels and adverse birth outcomes. In contrast, those investigating an association between socioeconomic status and low birth weight using nationwide data are limited in Japan. In this study, we investigated an association between municipal socioeconomic deprivation level and low birth weight by an ecological study.

METHODS

Nationwide municipal-specific Vital Statistics data from 2013 to 2017 were used. We calculated the low birth weight rate and standardized incidence ratio (SIR) for low birth weight for each municipality and plotted them on a Japanese map. Furthermore, the correlation coefficient between them and the deprivation level were calculated. In addition, a spatial regression model including other municipal characteristics was used to investigate an association between low birth weight and the deprivation level.

RESULTS

Municipalities with relatively high SIR for low birth weight were dispersed across all of Japan. The correlation coefficient between the socioeconomic deprivation level and low birth weight rate was 0.196 (p-value < 0.001) among municipalities, and that between the socioeconomic deprivation level and the SIR for low birth weight was 0.260 (p-value < 0.001). In addition, the spatial regression analysis showed the deprivation level was significantly and positively associated with low birth weight.

CONCLUSIONS

The socioeconomic deprivation level and low birth weight were positively associated, and a further study using individual data is warranted to verify reasons for the association.

Area deprivation and respiratory morbidities in children with bronchopulmonary dysplasia

INTRODUCTION

Infants and children diagnosed with bronchopulmonary dysplasia (BPD) have a higher likelihood of recurrent hospitalizations and asthma-like symptoms. Socio-environmental factors that influence the frequency and severity of pulmonary symptoms in these children during the preschool age are poorly understood. In this study, we used the Area Deprivation Index (ADI) to evaluate the relationship between the socio-environmental exposures in children with BPD and respiratory outcomes during the first few years of life.

METHODS

A registry of subjects recruited from outpatient BPD clinics at Johns Hopkins University (n = 909) and the Children's Hospital of Philadelphia (n = 125) between January 2008 and October 2021 was used. Subjects were separated into tertiles by ADI scores aggregated to ZIP codes. Caregiver questionnaires were used to assess the frequency of respiratory morbidities and acute care usage for respiratory symptoms.

RESULTS

The mean gestational age of subjects was 26.8 ± 2.6 weeks with a mean birthweight of 909 ± 404 g. The highest tertile (most deprived) of ADI was significantly associated with emergency department visits (aOR 1.72; p = 0.009), hospital readmissions (aOR 1.66; p = 0.030), and activity limitations (aOR 1.55; p = 0.048) compared to the lowest tertile. No association was seen with steroid, antibiotic or rescue medication use, trouble breathing, or nighttime symptoms.

CONCLUSION

In this study, children with BPD who lived in areas of higher deprivation were more likely to be rehospitalized and have ED visits for respiratory reasons. Identifying socio-environmental factors that contribute to adverse pulmonary outcomes in children with BPD may provide opportunities for earlier interventions to improve long-term pulmonary outcomes.

Is limited access to obstetric services associated with adverse birth outcomes? A cross-sectional study of Korean national birth data

OBJECTIVES

The geographical disparity in the access to essential obstetric services is a public health issue in many countries. We explored the association between timely access to obstetric services and the individual risk of adverse birth outcomes.

DESIGN

Repeated cross-sectional design.

SETTING

South Korean national birth data linked with a medical service provision database.

PARTICIPANTS

1 842 718 singleton livebirths from 2014 to 2018.

PRIMARY OUTCOME MEASURES

Preterm birth (PTB), post-term birth, low birth weight (LBW) and macrosomia.

RESULTS

In the study population, 9.3% of mothers lived in districts where the Time Relevance Index (TRI) was as low as the first quartile (40.6%). Overall PTB and post-term birth rates were 5.0% and 0.1%, respectively. Among term livebirths, LBW and macrosomia occurred in 1.0% and 3.3%, respectively. When the TRI is lower, representing less access to obstetric care, the risk of macrosomia was higher (adjusted OR=1.15, 95% CI 1.11 to 1.20 for Q1 compared with Q4). Similarly, PTB is more likely to occur when TRI is lower (1.05, 95% CI 1.00 to 1.10 for Q1; 1.03, 95% CI 1.01 to 1.05 for Q2). There were some inverse associations between TRI and post-term birth (0.80, 95% CI 0.71 to 0.91, for Q2; 0.84, 95% CI 0.76 to 0.93, for Q3).

CONCLUSIONS

We observed less accessibility to obstetric service is associated with higher risks of macrosomia and PTB. This finding supports the role of obstetric service accessibility in the individual risk of adverse birth outcomes.

Socioeconomic Inequalities in COVID-19 Incidence During Different Epidemic Phases in South Korea

Objective

Area-level socioeconomic status (SES) is associated with coronavirus disease 2019 (COVID-19) incidence. However, the underlying mechanism of the association is context-specific, and the choice of measure is still important. We aimed to evaluate the socioeconomic gradient regarding COVID-19 incidence in Korea based on several area-level SES measures.

Methods

COVID-19 incidence and area-level SES measures across 229 Korean municipalities were derived from various administrative regional data collected between 2015 and 2020. The Bayesian negative binomial model with a spatial autocorrelation term was used to estimate the incidence rate ratio (IRR) and relative index of inequality (RII) of each SES factor, with adjustment for covariates. The magnitude of association was compared between two epidemic phases: a low phase (<100 daily cases, from May 6 to August 14, 2020) and a rebound phase (>100 daily cases, from August 15 to December 31, 2020).

Results

Area-level socioeconomic inequalities in COVID-19 incidence between the most disadvantaged region and the least disadvantaged region were observed for nonemployment rates [RII = 1.40, 95% credible interval (Crl) = 1.01–1.95] and basic livelihood security recipients (RII = 2.66, 95% Crl = 1.12–5.97), but were not observed for other measures in the low phase. However, the magnitude of the inequalities of these SES variables diminished in the rebound phase. A higher area-level mobility showed a higher risk of COVID-19 incidence in both the low (IRR = 1.67, 95% Crl = 1.26–2.17) and rebound phases (IRR = 1.28, 95% Crl = 1.14–1.44). When SES and mobility measures were simultaneously adjusted, the association of SES with COVID-19 incidence remained significant but only in the low phase, indicating they were mutually independent in the low phase.

Conclusion

The level of basic livelihood benefit recipients and nonemployment rate showed social stratification of COVID-19 incidence in Korea. Explanation of area-level inequalities in COVID-19 incidence may not be derived only from mobility differences in Korea but, instead, from the country's own context.

Multilevel Factors Associated with Frailty among the Rural Elderly in Korea Based on the Ecological Model

Frailty is prevalent in the rural elderly and, as a result, they are vulnerable to serious health problems. The purpose of this study was to examine the multilevel factors affecting frailty among the rural elderly using the ecological model. A total of 386 participants aged 65 years or older from 60 rural areas were included in the study. Frailty was measured using the Cardiovascular Health Study frailty index. Multilevel logistic regression analysis was used to identify the factors affecting frailty among the rural elderly. The results show that the levels of prevalence for robust, pre-frailty, and frailty groups were 81 (21%), 216 (56%), and 89 (23%), respectively. As for intrapersonal factors, old age, lower than middle school education, low and moderate levels of physical activity, depressive symptoms, and cognitive dysfunction significantly increased the risk of frailty; however, no interpersonal and community factors were significant in affecting frailty. The findings indicate that individualized strategies to encourage physical activity, prevent depressive symptoms, and preserve cognitive function are needed to prevent frailty in the rural elderly.

Status and Determinants of Treatment Outcomes Among New Tuberculosis Patients in South Korea: A Retrospective Cohort Study

This is a retrospective cohort study using notification data in South Korea. We evaluated the nationwide status, regional differences, and the determinants of treatment outcomes among tuberculosis patients. Treatment success rate improved from 77.0% in 2012 to 86.0% in 2015. The lost to follow-up rate was higher among older people, males, and foreign nationals. Health care facilities designated for the Public-Private Mix (PPM) project showed higher success rate and lower rate of lost to follow-up. Moreover, municipalities with low regional deprivation index had higher PPM project coverage. Since there is a large regional difference in the coverage of the PPM project, an additional community-based support program should be implemented, especially for tuberculosis patients residing in region with low PPM project coverage.

Construction of an area-deprivation index for 2869 counties in China: a census-based approach

BACKGROUND

A paucity of data has made it challenging to construct a deprivation index at the lowest administrative, or county, level in China. An index is required to guide health equity monitoring and resource allocation to regions of greatest need. This study used China's 2010 census data to construct a county-level area-deprivation index (CADI).

METHODS

Data for 2869 counties from China's 2010 census were used to generate a CADI. Eleven indicators across four domains of deprivation were selected for principal component analysis with standardisation of the first principal component. Sensitivity analysis was used to test whether the population size and weighting method affected the index's robustness. Deprived counties identified by the CADI were then compared with China's official list of poverty-stricken counties.

RESULTS

The first principal component explained 60.38% of the total variation in the deprivation indicators. The CADI ranged from the least deprived value of -2.71 to the most deprived value of 2.92, with SD of 1. The CADI was found to be robust against county-level population size and different weighting methods. When compared with the official list of poverty-stricken counties in China, the deprived counties identified by the CADI were found to be even more deprived.

CONCLUSION

Constructing a robust area-deprivation index for China at the county level based on population census data is feasible. The CADI is a potential policy tool to identify China's most deprived areas. In the future, it may support health equity monitoring and comparison at the national and subnational levels.

Spatial analysis of inequalities in fetal and infant mortality due to avoidable causes

OBJECTIVES

to analyze social inequalities in spatial distribution of fetal and infant mortality by avoidable causes and identify the areas of greater risk of occurrence.

METHODS

avoidable deaths of fetal and infant residents of Recife/Brazil were studied. The rates of avoidable fetal and infant mortality were calculated for two five-year periods, 2006-2010 and 2011-2015. The scan statistics was used for spatial analysis and related to the social deprivation index.

RESULTS

out of the total 2,210 fetal deaths, 80% were preventable. Avoidable fetal mortality rates increased by 8.1% in the five-year periods. Of the 2,846 infant deaths, 74% were avoidable, and the infant mortality rate reduced by 0.13%.

CONCLUSIONS

in the spatial analysis, were identified clusters with higher risk for deaths. The social deprivation index showed sensibility with areas of worse living conditions.

Association of Early Menarche with Adolescent Health in the Setting of Rapidly Decreasing Age at Menarche

STUDY OBJECTIVE

This study aimed to investigate the association between age at menarche (AAM) and adverse health indicators in adolescent girls.

DESIGN

A retrospective cohort study.

SETTING

Population-based survey data.

PARTICIPANTS

A total of 319,437 female participants aged 12-18 years from the Korea Youth Risk Behaviour Web-based Survey.

INTERVENTIONS AND MAIN OUTCOME MEASURES

We assessed associations between AAM (categorized as ≤10, 11, and ≥12) and health indicators (poor self-rated health, high psychological stress, unhappiness, sexual initiation, and pregnancy). Covariates were individual-level (bodyweight, living with family, parent's education, household wealth, and presence of parents and siblings) and community-level factors (year of birth, single-sex education and level of school, urbanization level of school area, year of survey, and regional deprivation). Odds ratios (ORs) for each adverse health indicator were examined by each AAM group using multivariable regression analyses. For pregnancy, we calculated relative risks (RRs) using a log-binomial regression model.

RESULTS

Age at menarche was <12 in 42% of our study population. Nearly one-half of the girls born in the early 2000s went through menarche before the age of 12 years, whereas only one-third of girls born in the early 1990s went through menarche before the age of 12 years. Girls who experienced menarche at age ≤10 or age 11 years were more likely to show self-rated poor health (AAM ≤ 10: OR, 1.28; 95% confidence intervals [CI], 1.22-1.34; AAM = 11: OR, 1.16; 95% CI, 1.12-1.21), high stress (OR, 1.19; 95% CI, 1.14-1.23, and OR, 1.10; 95% CI, 1.06-1.14), and sexual initiation (OR, 2.21; 95% CI, 2.05-2.38, and OR, 1.32; 95% CI, 1.23-1.41) compared to those with AAM ≥12 years when data were adjusted for all covariates. AAM ≤10 years was associated with consistently higher odds for poor health than AAM ≥12 years. The ORs of sexual initiation increased with earlier AAM. Risk of pregnancy was similar across AAM groups when individual- and community-level covariates were controlled for.

CONCLUSION

Early menarche, defined as <12 years, can be still a useful indicator in adolescent health interventions to identify high-risk groups in the setting of declining AAM.

Regional Differences in Years of Life Lost in Korea from 1997 to 2015

BACKGROUND

Reducing the gaps in health inequality at a regional level and improving health equity have been emphasized in Korea, it is essential to accurately measure the burden of disease by region. This study aimed to estimate years of life lost (YLLs) in 17 Si and Do of Korea from 1997 to 2015 and determine the trends of regional differences in health status and disease structure.

METHODS

YLL was calculated by subtracting the age at death from the life expectancy. Data on the region, gender, and age-stratified cause-specific death were obtained from the Korean Statistical Information Service of Statistics Korea.

RESULTS

Age-standardized YLLs per 100,000 population decreased by year in all regions from 1997 to 2015 by 27.4% (27.5% for men; 27.2% for women). Despite the decline in YLLs, the regions with the highest and lowest YLLs did not change between 1997 and 2015. The diseases showing regional differences were caused by injury, often classified as avoidable mortality. We also confirmed that YLLs were higher in the regions with a higher deprivation index.

CONCLUSION

The present study identified that YLLs differed by regions in Korea with specific causes. The findings of this study can be used by decision-makers to prioritize the reduction of regional gaps in premature deaths.

Trends of Social Inequalities in the Specific Causes of Infant Mortality in a Nationwide Birth Cohort in Korea, 1995-2009

The relationship between social disparity and specific causes of infant mortality has rarely been studied. The present study analyzed infant mortality trends according to the causes of death and the inequalities in specific causes of infant mortality between different parental social classes. We analyzed 8,209,836 births from the Statistics Korea between 1995 and 2009. The trends of disparity for cause-specific infant mortality according to parental education and employment were examined using the Cox proportional hazard model for the birth-year intervals of 1995-1999, 2000-2004, and 2005-2009. Adjusted hazard ratios were calculated after adjusting for infants' gender, parents' age, maternal obstetrical history, gestational age, and birth weight. An increasing trend in social inequalities in all-cause infant mortality according to paternal education was evident. Social inequalities in infant mortality were greater for "Not classified symptoms, signs and findings" (International Classification of Diseases 10th revision [ICD-10]: R00-R99) and "Injury, poisoning and of external causes" (S00-T98), particularly for "Ill-defined and unspecified causes" (R990) and "Sudden infant death syndrome (SIDS)" (R950); and increased overtime for "Not classified symptoms, signs and findings" (R00-R99), "Injury, poisoning and of external causes" (S00-T98) and "Conditions in perinatal period" (P00-P96), particularly for "SIDS" (R950) and "Respiratory distress syndrome of newborns (RDS)" (P220). The specific causes of infant mortality, in particular the "Not classified causes" (R00-R99 coded deaths) should be investigated more thoroughly to reduce inequality in health.