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

Educational inequalities in adult mortality: a systematic review and meta-analysis of the Asia Pacific region

OBJECTIVES

In this study, we aim to analyse the relationship between educational attainment and all-cause mortality of adults in the high-income Asia Pacific region.

DESIGN

This study is a comprehensive systematic review and meta-analysis with no language restrictions on searches. Included articles were assessed for study quality and risk of bias using the Joanna Briggs Institute critical appraisal checklists. A random-effects meta-analysis was conducted to evaluate the overall effect of individual level educational attainment on all-cause mortality.

SETTING

The high-income Asia Pacific Region consisting of Japan, South Korea, Singapore and Brunei Darussalam.

PARTICIPANTS

Articles reporting adult all-cause mortality by individual-level education were obtained through searches conducted from 25 November 2019 to 6 December 2019 of the following databases: PubMed, Web of Science, Scopus, EMBASE, Global Health (CAB), EconLit and Sociology Source Ultimate.

PRIMARY AND SECONDARY OUTCOME MEASURES

Adult all-cause mortality was the primary outcome of interest.

RESULTS

Literature searches resulted in 15 345 sources screened for inclusion. A total of 30 articles meeting inclusion criteria with data from the region were included for this review. Individual-level data from 7 studies covering 222 241 individuals were included in the meta-analyses. Results from the meta-analyses showed an overall risk ratio of 2.40 (95% CI 1.74 to 3.31) for primary education and an estimate of 1.29 (95% CI 1.08 to 1.54) for secondary education compared with tertiary education.

CONCLUSION

The results indicate that lower educational attainment is associated with an increase in the risk of all-cause mortality for adults in the high-income Asia Pacific region. This study offers empirical support for the development of policies to reduce health disparities across the educational gradient and universal access to all levels of education.

PROSPERO REGISTRATION NUMBER

CRD42020183923.

Occupational inequalities in mortality in Korea using nationally representative mortality follow-up data from the late 2000s and after

Many Korean and international studies have found higher mortality rates and poorer health conditions among manual workers than among non-manual workers. However, a recent study using unlinked data argued that since the economic crisis in Korea in the late 2000s, the mortality estimates of male Korean non-manual workers have been higher than those of manual workers. Our work using individually linked data from the late 2000s and after aimed to examine mortality inequality by occupational class. We analyzed Korea National Health and Nutrition Examination Survey data that were individually linked to cause-of-death data. Cox regression analysis was used to identify the hazard ratios for mortality by occupational class. Of 11,766 males aged between 35 and 64, 397 died between 2007 and 2018: 142 died from cancer, 68 from cardiovascular disease, 88 from external causes, and 99 from other causes. After controlling for age, the mortality estimates for manual workers were 1.85 times higher than those for upper non-manual workers (p<0.05). We observed no evidence of reversed mortality inequality among occupational classes in Korea since the 2000s; this previously reported finding might have been due to numerator-denominator bias arising from the use of unlinked data.

Estimation of socioeconomic inequalities in mortality in Japan using national census-linked longitudinal mortality data

BACKGROUND

We aimed to develop census-linked longitudinal mortality data for Japan and assess its validity as a new resource for estimating socioeconomic inequalities in health.

METHODS

Using deterministic linkage, we identified, from national censuses for 2000 and 2010 and national death records, persons and deceased persons who had unique personal identifiers (generated using sex, birth year/month, address, and marital status). For the period 2010-2015, 1 537 337 Japanese men and women aged 30-79 years (1.9% in national census) were extracted to represent the sample population. This population was weighted to adjust for confounding factors. We estimated age-standardized mortality rates (ASMRs) by education level and occupational class. The slope index of inequality (SII) and relative index inequality (RII) by educational level were calculated as inequality measures.

RESULTS

The reweighted sample population's mortality rates were somewhat higher than those of the complete registry, especially in younger age-groups and for external causes. All-cause ASMRs (per 100 000 person-years) for individuals aged 40-79 years with high, middle, and low education levels were 1078 (95% confidence interval: 1051-1105), 1299 (1279-1320), and 1670 (1634-1707) for men, and 561 (536-587), 601 (589-613), and 777 (745-808) for women, respectively, during 2010-2015. SII and RII by educational level increased among both sexes between 2000-2005 and 2010-2015, which indicates mortality inequalities increased.

CONCLUSIONS

The developed census-linked longitudinal mortality data provide new estimates of socioeconomic inequalities in Japan that can be triangulated with estimates obtained with other methods.

The Contribution of Material, Behavioral, Psychological, and Social-Relational Factors to Income-Related Disparities in Cardiovascular Risk Among Older Adults

Supplemental digital content is available in the text.

Understanding the factors underlying health disparities is vital to developing strategies to improve health equity in old age. Such efforts should be encouraged in Korea.

Analysis of factors contributing to occupational health inequality in Korea: a cross-sectional study using nationally representative survey data

Background

Despite the consensus that higher occupational classes tend to have better health and lower mortality rates, one study has reported reversed occupational gradients in mortality rates among Korean men after the economic crisis in the late 2000s. To examine these patterns of health inequality in more detail, we investigated the tendency of occupational gradients in socioeconomic position and multiple pathway indicators known to affect mortality in Korea.

Methods

We used data from 4176 men aged 35–64 in Korea derived from the 2007–2009 and 2013–2015 Korean National Health and Nutrition Examination Surveys. We compared the age-standardized prevalence and age-adjusted mean values of each contributing factor to health inequality among occupational groups, which are divided into upper non-manual workers, lower non-manual workers, manual workers, and others. Contributing factors included childhood and adulthood socioeconomic position indicators, biological risk factors, health behaviors, psychosocial factors, and work environment.

Results

Upper non-manual workers had prominently higher levels of education, income, parental education, and economic activity than lower non-manual and manual workers. The rates of smoking and high-risk alcohol consumption were lower, and the rate of weight control activities was higher, in the non-manual classes. Further, the rates of depression and suicidal ideation were lower, and perceptions of the work environment were more favorable, among non-manual workers than among their manual counterparts.

Conclusions

We detected occupational inequality in a wide range of socioeconomic positions and pathway indicators in Korea with consistently favorable patterns for upper non-manual workers. These occupational gradients do not support the previously reported reversed pattern of higher mortality rates in non-manual groups versus in the manual job class in Korea.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13690-021-00638-9.

Distribution of wealth-stratified inequalities on maternal and child health parameters and influences of maternal-related factors on improvements in child health survival rate in Bangladesh

This study investigates the influence of household socioeconomic status and maternal risk factors and health-care service availability on changes in the under-five mortality rate (U5MR) in Bangladesh. Potential risk factors that influence U5MRs were investigated using multilevel logistic regression analysis and 29,697 data points from the Bangladesh Demographic and Health Surveys, 2004-2014. Maternal and child health parameters such as childhood morbidity, low vaccination coverage, poor utilization of perinatal care, and malnutrition were found to be more concentrated in poorer households. Pooled estimates indicated that the aggregate odds of U5MR risk declined by 18% to 2007 to 38% to 2014 compared to 2004. However, inadequate antenatal care, short birth interval, primiparity, illiteracy, delayed conception, and low socioeconomic status were significantly associated with a higher risk of under-five mortality. The magnitude of inequality using these measures were significantly associated with large variations in U5MR changes. Although a significant reduction in U5MR in Bangladesh was found in this study, substantial socioeconomic variations still persist. The analysis suggests that decreasing inequality in society is required for further reductions in child mortality. This will help to achieve a more equitable distribution of child and neonatal outcomes and assist the achievement of Sustainable Development Goals 3.2 by 2030.

[Analysis of Prognosis according to Type of Health Insurance in Five Major Gastrointestinal Cancer Patients in Public Hospitals: Single-institution Retrospective Study]

Background/Aims

Public hospitals were established to provide high quality medical services to low socioeconomic status patients. This study examined the effects of public hospitals on the treatment and prognosis of patients with five-major gastrointestinal (GI) cancers (stomach cancer, colon cancer, liver cancer, bile duct cancer, and pancreatic cancer).

Methods

Among the 1,268 patients treated at Seoul National University Boramae Medical Center from January 2010 to December 2017, 164 (13%) were in the medicare group. The data were analyzed to identify and compare the clinical manifestations, treatment modality, and clinical outcomes between the groups.

Results

No statistically significant differences in the clinical data (age, sex), treatment method, and five-year survival rate were observed between the health insurance group and medicare group in the five major GI cancer patients. On the other hand, some medicare group patients tended more comorbidities and fewer treatment options than health insurance patients.

Conclusions

Public hospitals have a positive effect on the treatment and prognosis in medicare group patients with the five-major GI cancers.

Socioeconomic disparities in self-rated health in two East Asian countries: Comparative study between Japan and Korea

Although Japan and South Korea share a number of commonalities, social security systems are very different. We opt to compare socioeconomic disparities in self-rated health between these two countries. The analytic sample included those aged 20 years and older from the nationally representative surveys in Japan (Comprehensive Survey of Living Conditions) and South Korea (Korean Community Health Survey). As socioeconomic status, we used income (quintiles of equivalized annual household income) and education (five categories). We measured socioeconomic inequalities using two indices; the Slope Index of Inequality (SII) and the Relative Index of Inequality (RII), in each age group for each country. In Japan, we found relatively little evidence of socioeconomic inequalities in self-rated health over the life course, on either the absolute or relative scale. In Korea, the absolute inequality assessed by SII of self-rated poor health was higher in middle and old age groups compared to other age groups, while relative inequality measured by RII was significantly higher in younger ages. In Japan with more generous welfare system to the older generations, health inequality was relatively lower compared to Korea. The gaps in health status for Korean people suggest where social policy might direct their efforts in the future - (a) reducing inequalities in working-age people by addressing the gap between standard workers & non-standard workers; and (b) improving the financial conditions of older people by shoring up the social security system.

Spontaneous and repeat spontaneous abortion risk in relation to occupational characteristics among working Korean women: a cross-sectional analysis of nationally representative data from Korea

Background

The association between spontaneous abortion (SA) and occupational characteristics among working women is not well-studied. This study aimed to assess the risk of SA and occupational factors such as occupational classification, working hours, and work schedules among working Korean women aged > 19 years.

Methods

In this cross-sectional study, 4078 working women were identified from among 25,534 workers in the Korea National Health and Nutrition Examination Surveys V (2010–2012) database, to obtain data on SA history and the number of SAs. Odds ratios (ORs) and 95% confidence intervals (CIs) for SA were calculated using multiple logistic regression models after adjusting for age, education, household income, cigarette smoking, alcohol consumption, and obesity status. The weighted prevalence for the number of SAs was calculated according to occupational characteristics to demonstrate the SA status among working Korean women.

Results

SA occurrence was reported in 5.7% of the study participants. The ORs (95% CIs) for SA were significantly higher in pink-, green-, and blue-collared workers than in white-collared workers. Regarding weekly working hours, compared with ≤50 h spent working, the ORs (95% CIs) for 51–60, 61–70, and > 70 h per week were 1.26 (0.87–1.84), 1.63 (1.04–2.56), and 1.73 (1.10–2.70), respectively. A significantly higher weighted prevalence of repeat SAs was observed in pink- and green-collared workers and in those who worked long hours.

Conclusion

We found a significant association between SA, repeat SA, and occupational characteristics among working Korean women.

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.

Measurement of Socioeconomic Position in Research on Cardiovascular Health Disparities in Korea: A Systematic Review

OBJECTIVES

The validity of instruments measuring socioeconomic position (SEP) has been a major area of concern in research on cardiovascular health disparities. The purpose of this systematic review is to identify the current status of the methods used to measure SEP in research on cardiovascular health disparities in Korea and to provide directions for future research.

METHODS

Relevant articles were obtained through electronic database searches with manual searches of reference lists and no restriction on the date of publication. SEP indicators were categorized into compositional, contextual, composite, and life-course measures.

RESULTS

Forty-eight studies published from 2003 to 2018 satisfied the review criteria. Studies utilizing compositional measures mainly relied on a limited number of SEP parameters. In addition, these measures hardly addressed the time-varying and subjective features of SEP. Finding valid contextual measures at the organizational, community, and societal levels that are appropriate to Korea's context remains a challenge, and these are rarely modeled simultaneously. Studies have rarely focused on composite and life-course measures.

CONCLUSIONS

Future studies should develop and utilize valid compositional and contextual measures and appraise social patterns that vary across time, place, and culture using such measures. Studies should also consider multilevel influences, adding a focus on the interactions between different levels of intertwined SEP factors to advance the design of research. More attention should be given to composite and life-course measures.

Descriptive Study on the Korean Status of Percutaneous Coronary Intervention Using National Health Insurance Service-National Sample Cohort (NHIS-NSC) Database: Focused on Temporal Trend

Background and Objectives

Percutaneous coronary intervention (PCI) is an indispensable treatment modality in coronary artery disease. However, there is still inadequacy of comprehensive knowledge on the Korean status and trend of this important procedure using nation-wide and representative data.

Methods

National Health Insurance Service-National Sample Cohort is a database containing demographic, health insurance reimbursement for patient management and health screening data of about one million Koreans for 12 years (2002–2013). Annual procedure rate for PCI was estimated by bootstrapping as per 100,000 person-years.

Results

Among the whole cohort, total 12,186 PCI's were done during the study period. Mean age of subjects who underwent PCI was 57.6±11.2 years and male:female proportion was 68%:32%. Death from all cause occurred in 1,843 (15.1%), death from ischemic heart diseases in 662 (5.4%), death from all cardiovascular cause in 872 (7.2%) during the follow-up. The proportion of the primary PCI for acute myocardial infarction was estimated to be 24.0%. Estimated annual rate of PCI increased from median 29.1 (95% confidence interval [CI], 26.6–32.1) in 2002 to 107.7 (95% CI, 103.0–113.8) per 100,000 person-years in 2013. In this cohort, PCI was performed in total 180 hospitals, which annually increased from 59 in 2002 to 153 in 2013.

Conclusions

PCI had increased in volume from 2002 to 2013. This descriptive data may be considered in policy making and planning further direction of management of coronary artery disease in Korea.

Changes in inequality of childhood morbidity in Bangladesh 1993-2014: A decomposition analysis

INTRODUCTION

Child health remains an important public health concern at the global level, with preventable diseases such as diarrheal disease, acute respiratory infection (ARI) and fever posing a large public health burden in low- and middle-income countries including Bangladesh. Improvements in socio-economic conditions have tended to benefit advantaged groups in societies, which has resulted in widespread inequalities in health outcomes. This study examined how socioeconomic inequality is associated with childhood morbidity in Bangladesh, and identified the factors affecting three illnesses: diarrhea, ARI and fever.

MATERIALS AND METHODS

A total of 43,860 sample observations from the Bangladesh Demographic and Health Survey, spanning a 22-year period (1993-2014), were analysed. Concentration curve and concentration index methods were used to evaluate changes in the degree of household wealth-related inequalities and related trends in childhood morbidity. Regression-based decomposition analyses were used to attribute the inequality disparities to individual determinants for the three selected causes of childhood morbidity.

RESULTS

The overall magnitude of inequality in relation to childhood morbidity has been declining slowly over the 22-year period. The magnitude of socio-economic inequality as a cause of childhood morbidity varied during the period. Decomposition analyses attributed the inequalities to poor maternal education attainment, inadequate pre-delivery care, adverse chronic undernutrition status and low immunisation coverage.

CONCLUSIONS

High rates of childhood morbidity were observed, although these have declined over time. Socio-economic inequality is strongly associated with childhood morbidity. Socio-economically disadvantaged communities need to be assisted and interventions should emphasise improvements of, and easier access to, health care services. These will be key to improving the health status of children in Bangladesh and should reduce economic inequality through improved health over time.

Relationship between the shift of socioeconomic status and cardiovascular mortality

BACKGROUND

The aim of this study is to investigate whether upward or downward shifts in socioeconomic status have an effect on cardiovascular mortality.

DESIGN

A retrospective cohort study.

METHODS

Among the Korean National Health Insurance Service National Sample Cohort, 178,812 subjects were selected who were over 20 years of age as of 2002, with available data on routine health check and free of a diagnosis of ischaemic heart disease, stroke, heart failure or cancer at baseline. Cause of death was identified by the death certificate. Stratification of socioeconomic status was done by income as low (lower 30th percentile), high (higher 30th percentile) and middle, which was reclassified annually. Shift in socioeconomic status was defined as any change in the income class from baseline.

RESULTS

During the follow-up of a median 10 years, cardiovascular mortality was significantly higher among middle and low socioeconomic status groups (hazard ratio and 95% confidence interval for middle 1.92 (1.68-2.19) and low 1.73 (1.50-2.00)) compared to the high socioeconomic status group after adjustment for age, gender, residence, blood pressure, fasting glucose, smoking and medications (statins and antiplatelet agents). In the same regression model, an upward shift of socioeconomic status was associated with a lower risk of cardiovascular death (hazard ratio 0.46, 95% confidence interval 0.40-0.52), while a downward shift was not a significant predictor.

CONCLUSION

An upward shift of socioeconomic status was associated with a lower risk of cardiovascular mortality after adjustment for baseline socioeconomic status, conventional risk factors and risk-reducing pharmacological treatments.

The parental co-immunization hypothesis: An observational competing risks analysis

The main interest of this study is the hypothesis that contact with small children may be beneficial for the parents’ later health and mortality (because of changes in their immune system). For this purpose, we document the relationship of a set of individual characteristics—including parenthood and marital state—and socioeconomic status with an individual’s cause of death. Using a novel and rich data set made available by the Office for National Statistics Longitudinal Study (ONS-LS), which follows 1% of the population of England and Wales along five census waves 1971, 1981, 1991, 2001, and 2011, our competing risks analysis yields several striking results: (1) Females with children have a 72.5% reduced risk of dying of cancer compared to childless females (for childless females of age 70, this corresponds to a risk of dying of cancer of 1.3% compared to a risk of about 1.3 × 0.275 = 0.4% for females with children). (2) Males have a 171% increased chance of dying of cancer when they are married (e.g., a baseline probability of 1.2% when 75 year old) compared to unmarried males. (3) Females with children have only a 34% risk of dying of heart disease (corresponding to a conditional probability of 0.3% when aged 65) relative to females without children and (4) a 53% chance of dying of infections (i.e., 0.1% at 65 years of age) compared to the risk for females without children. (5) At the same age, married men have an increased expectation of 123% of dying of heart disease (corresponding to an expected death probability of 0.7%) compared to unmarried men. (6) High income and house ownership is always associated with higher survival but less so than having children. While these results document a relationship between the presence of children and mortality, the specific transmission mechanisms remain unclear and we cannot make causality assertions.

Influence of Income on Cancer Incidence and Death among Patients in Aomori, Japan

Background: Aomori Prefecture has experienced the highest cancer-related mortality rates since the 2000s in Japan. In addition, income of residents in Aomori Prefecture is lower than that of a countrywide average. Aims of this study were to examine the relationships of the incidence and mortality rates of common cancers (stomach, colorectal, liver, lung, breast, cervical, and prostate) with the income levels of residential income area and clarify the factors contributing to the high mortality rates in Aomori prefecture.Methods: We included data on all patients diagnosed with stomach, colorectal, liver, lung, breast, cervical, or prostate cancer in the Aomori cancer registry database between 2010 and 2012. Age-standardized incidence rates and incidence rate ratios were calculated. Risk of cancer mortality related to economic disparities was determined via multivariable Cox regression analysis and adjusted for age, sex, and stage at diagnosis in the multivariable model. Results: We identified 21,240 eligible cancer patients. There were no differences in AIRs and IRRs among patients with stomach, colorectal, or lung cancer according to income. Contrarily, AIRs and IRRs were higher in higher-income areas than in lower-income areas among patients with breast, cervical, or prostate cancer. There were no significant differences in HRs according to income for any cancer type. Conclusions:Patients with higher income were diagnosed with early-stage disease more frequently, and they had higher AIRs for breast, cervical, and prostate cancers than those with middle and low incomes. However, there were no significant differences in hazard ratios.

The Change of Self-Rated Health According to Working Hours for Two Years by Gender

OBJECTIVE

The aim of this study was to confirm the association between working hours and self-rated health, and to find the degree of changes in health level by working hours according to gender.

METHODS

This study was based on the 929 workers (571 men and 358 women) from the Korean Labor and Income Panel Study during 2004⁻2006. To minimize the healthy worker effects, the study subjects included only those who did not have any chronic diseases, and who answered their health status as "moderate" or above in the baseline. Logistic regression analysis was used to confirm the associations between working hours and self-rated health.

RESULTS

In men, working hours per week of 47⁻52 h, 53⁻68 h, and >68 h were associated with 1.2, 1.3, and 1.1 times increases, respectively, in the odds ratio on worsened self-rated health, compared with the reference group (40⁻46 h). On the other hand, the risks were 1.0, 2.2, and 2.6 times increases in women. However, the results were different according to gender in the group with less than 40 h. The men with less than 40 h had a 0.9 times odds ratio on worsened self-rated health. For the women with less than 40 h, the odds ratio on self-rated health was 5.4 times higher than the reference group.

CONCLUSIONS

Working more than 52 h per week had a negative effect on health, regardless of gender. However, in the group with less than 40 h, the negative association between working hours and self-rated health were shown only in women. Health outcomes due to working hours may differ by gender. Therefore, further studies are needed to explore the causes of these results.

Role of allostatic load and health behaviours in explaining socioeconomic disparities in mortality: a structural equation modelling approach

Background

The relationship between socioeconomic status and mortality has been well established; however, the extent to which biological factors mediate this relationship is less clear, and empirical evidence from non-Western settings is limited. Allostasis, a cumulative measure of physiological dysregulation, has been proposed as the underlying mechanism linking socioeconomic status to adverse health outcomes. The current study aimed to ascertain the contribution of allostatic load (AL) and health behaviours to socioeconomic inequalities in mortality among Korean adults.

Methods

The sample comprised 70 713 middle-aged and older-aged adults, aged 40–79 years from the Korean Metabolic Syndrome Mortality Study. Using structural equation modelling (SEM), mediation analyses were performed to estimate the effects of socioeconomic position (SEP) on mortality over the follow-up and the extent to which AL, physical exercise and non-smoking status mediate the association between SEP and mortality.

Results

A total of 5618 deaths (7.9%) occurred during the mean follow-up of 15.2 years (SD 2.9). SEM confirmed a direct significant effect of SEP on mortality, as well as significant indirect paths through AL, physical exercise and non-smoking status.

Conclusions

Our findings provide support for the mediating role of AL and health behaviours in the link between SEP and mortality. Policies designed to reduce social disparities in mortality in the long term should primarily focus on reducing stress and promoting healthy lifestyles among the socially disadvantaged groups. Future studies should further assess the role of other mediators such as psychosocial factors, which may contribute to socioeconomic inequalities in mortality.

Do Mothers with Lower Socioeconomic Status Contribute to the Rate of All-Cause Child Mortality in Kazakhstan?

Background

This study aimed to explore whether or not mothers with higher educational and wealth status report lower rate of child mortality compared to those with less advantageous socioeconomic situation.

Methods

Data used were cross-sectional and collected from Multiple Indicator Cluster Survey in Kazakhstan conducted in 2015. Subjects experiencing childbirth were 9278 women aging between 15 and 49 years. The associations between maternal education and household wealth status with child mortality were examined by multivariate analytical methods.

Results

The overall prevalence of child mortality was 6.7%, with noticeable variations across the different regions. Compared with women who had the highest educational status, those with upper and lower secondary were 1.47 and 1.89 times more likely to experience child death. Women in the lowest and second lowest wealth quintile had 2.74 and 2.68 times higher odds of experiencing child death compared with those in the richest wealth status households.

Conclusions

Policy makers pay special attention to improving socioeconomic status of the mothers in an effort to reduce child mortality in the country. Women living in the disadvantaged regions with poor access to quality health care services should be regarded as a top priority.

Factors associated with spontaneous abortion: a cross-sectional study of Chinese populations

Background

Spontaneous abortion (SA) is one of the prevalent negative reproductive outcomes among women around the world, which is a great challenge faced by maternal health promotion. The present study is aimed to explore the association between SA and socioeconomic status (SES) and provides reference for policy makers to improve strategies on maternal health promotion.

Methods

A cross-sectional analysis was conducted with baseline data from a large-scale population-based cohort study of 0.5 million people from 10 geographically diverse areas of China recruited from 2004 to 2008. The study collected data from 84,531 women aged 35–45 years old in the baseline survey of China Kadoorie Biobank. Participants were interviewed using a standardized questionnaire, and information on demographic-socioeconomic as well as reproductive health status was collected. Odds ratios (OR) with 95% CI, estimated by a multistep logistic regression, were used to approximate the associations between SA occurrence and characteristics of SES. A stratification analysis was also applied to find out how SES influenced women’s reproductive health outcomes differently between rural and urban areas. The model was adjusted for age at study date, tea consumption, alcohol consumption, cigarette smoking, and number of induced abortion.

Results

The risk of SA in rural was 1.68 times greater than in urban (AOR = 1.68, 95%CI: 1.54–1.84). Women with high income had a decreased risk of SA when compared with that of women with low income (AOR = 0.90, 95%CI: 0.84–0.97). Compared with women in low educational attainment, women in higher educational attainment had a lower prevalence of SA (AOR = 0.90, 95%CI: 0.82–0.98). The risk of SA only reduced in factory worker (AOR = 0.59, 95%CI: 0.53–0.66) and professional worker (AOR = 0.75, 95%CI: 0.66–0.84) compared with agriculture and related workers. After stratifying by rural/urban, the association between income and SA in urban (AOR = 0.88, 95%CI: 0.78–0.99) was stronger than that in rural (AOR = 0.92, 95%CI: 0.84–1.00). Association between education and SA was found in urban (AOR = 0.66, 95%CI: 0.55–0.78) but not in rural (AOR = 1.05, 95%CI: 0.34–1.17), and there was no difference on how occupation impacted SA among women between the two subgroups.

Conclusions

Generally women with lower SES status had a higher risk of SA. Lower income and educational attainment were inversely associated with the risk of SA. Women with agricultural and related work had a significantly higher prevalence of SA. Interventions could be targeted more on women with low SES to increase both health profits as well as economic gains for health programs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12978-017-0297-2) contains supplementary material, which is available to authorized users.