Social Inequities in the Survival of Liver Cancer: A Nationwide Cohort Study in Korea, 2007-2017.

BACKGROUND: To analyze the effects of socioeconomic status (type of insurance and income level) and cancer stage on the survival of patients with liver cancer in Korea. METHODS: A retrospective cohort study was constructed using data from the Healthcare Big Data Platform project in Korea between January 1, 2007, and December 31, 2017. A total of 143,511 patients in Korea diagnosed with liver cancer (International Classification of Diseases, 10th Revision [ICD-10] codes C22, C220, and C221) were followed for an average of 11 years. Of these, 110,443 died. The patient's insurance type and income level were used as indicators of socioeconomic status. Unadjusted and adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using a Cox proportional hazards regression model to analyze the relationship between the effects of sex, age, and cancer stage at first diagnosis (Surveillance, Epidemiology, and the End Results; SEER), type of insurance, and income level on the survival of patients with liver cancer. The interactive effects of the type of insurance, income level, and cancer stage on liver cancer death were also analyzed. RESULTS: The lowest income group (medical aid) showed a higher risk for mortality (HR (95% CI); 1.37 (1.27-1.47) for all patients, 1.44 (1.32-1.57) for men, and 1.16 (1.01-1.34) for women) compared to the highest income group (1-6) among liver cancer (ICD-10 code C22) patients. The risk of liver cancer death was also higher in the lowest income group with a distant cancer stage (SEER = 7) diagnosis than for any other group. CONCLUSION: Liver cancer patients with lower socioeconomic status and more severe cancer stages were at greater risk of death. Reducing social inequalities is needed to improve mortality rates among patients in lower social class groups who present with advanced cancer.

Widening Social Inequalities in Cancer Mortality of Children Under 5 Years in Korea.

BACKGROUND: To investigate the effect of parental social class on cancer mortality in children under 5 in Korea, two birth cohorts were constructed by linking national birth data to under-5 death data from the Statistics Korea for 1995-1999 (3,323,613 births) and 2010-2014 (2,297,876 births). METHODS: The Cox proportional hazards model adjusted for covariates was used in this study. RESULTS: Social inequalities of under-5 cancer mortality risk in paternal education and paternal employment status were greater in 2010-2014 than in 1995-1999. The gap of hazard ratio (HR) of under-5 cancer mortality between lower (high school or below) and higher (university or higher) paternal education increased from 1.23 (95% confidence interval, 1.041.46) in 1995-1999 to 1.45 (1.11-1.97) in 2010-2014; the gap of HR between parents engaged in manual work and non-manual work increased from 1.32 (1.12-1.56) in 1995-1999 to 1.45 (1.12-1.89) in 2010-2014 for fathers, and from 1.18 (0.7-1.98) to 1.69 (1.03-2.79) for mothers. When the parental social class was lower, the risk of under-5 cancer mortality was higher in not only adverse but normal births. CONCLUSION: Social inequalities must be addressed to reduce the disparity in cancer mortality of children under 5 years old.

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.

Effects of Marital Status and Income on Hypertension: The Korean Genome and Epidemiology Study (KoGES).

OBJECTIVES: This study aimed to analyze the associations of income, marital status, and health behaviors with hypertension in male and female over 40 years of age in the Korea. METHODS: The data were derived from the Korean Genome and Epidemiology Study (KoGES; 4851-302) which included 211 576 participants. To analyze the relationships of income, marital status, and health behaviors with hypertension in male and female over 40 years of age, multiple logistic regression was conducted with adjustments for these variables. RESULTS: The prevalence of hypertension increased linearly as income decreased. The odds ratio for developing hypertension in people with an income of <0.5 million Korean won (KRW) compared to ≥6.0 million KRW was 1.55 (95% confidence interval [CI], 1.25 to 1.93) in the total population, 1.58 (95% CI, 1.27 to 1.98) in male, and 1.07 (95% CI, 0.35 to 3.28) in female. The combined effect of income level and marital status on hypertension was significant. According to income level and marital status, in male, low income and divorce were most associated with hypertension (1.76 times; 95% CI, 1.01 to 3.08). However, in female, the low-income, married group was most associated with hypertension (1.83 times; 95% CI, 1.71 to 1.97). CONCLUSIONS: The results of this study show that it is necessary to approach male and female marital status separately according to income in health policies to address inequalities in the prevalence of hypertension.

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.

Role of Parental Social Class in Preterm Births and Low Birth Weight in Association with Child Mortality: A National Retrospective Cohort Study in Korea.

PURPOSE: We explored the role of parental social class in preterm birth (PTB) and low birth weight (LBW) in association with child mortality in Korea. MATERIALS AND METHODS: A total of 7,302,732 births in Korea between 1995 and 2007 were used for designing the national retrospective cohort study. Kaplan-Meier survival curves and Cox proportional hazard models were used to determine the risk of child death after adjusting for covariates. RESULTS: Parental social class was associated with adverse birth outcomes and child mortality in Korea. Parental social class increased the strength of the relationship of adverse birth outcomes with child mortality. Child mortality was higher among PTB and LBW infants from parents with a lower social class than normal births from parents with a higher social class. In particular, the disparity in child mortality according to parental social class was greater for LBW and PTB than intrauterine growth retardation births. When one of the parents had a middle-school education or lower, the disparity in child mortality due to adverse birth outcomes was large regardless of the other spouse's educational status. Inactive economic status for the father, as well as an occupation in manual labor by the mother, increased the risk of child mortality. CONCLUSION: Strong relationships for social inequalities and adverse birth outcomes with inequalities in child mortality in South Korea were found in this study. Tackling social inequalities, as well as reducing adverse birth outcomes, are needed to reduce the disparities in child mortality in South Korea.

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.

Representative levels of blood lead, mercury, and urinary cadmium in youth: Korean Environmental Health Survey in Children and Adolescents (KorEHS-C), 2012-2014.

BACKGROUND: This study examined levels of blood lead and mercury, and urinary cadmium, and associated sociodemographic factors in 3-18 year-old Korean children and adolescents. MATERIALS AND METHODS: We used the nationally representative Korean Environmental Health Survey in Children and Adolescents data for 2012-2014 and identified 2388 children and adolescents aged 3-18 years. The median and 95th percentile exposure biomarker levels with 95% confidence intervals (CIs) were calculated. Multivariate regression analyses were performed on log transformed exposure biomarker levels adjusted for age, sex, area, household income, and father's education level. The median exposure biomarker levels were compared with data from Germany, the US, and Canada, as well as the levels of Korean children measured at different times. RESULTS: The median levels of blood lead and mercury, as well as urinary cadmium were 1.23µg/dL, 1.80µg/L, and 0.40µg/L (95% CIs, 1.21-1.25, 1.77-1.83, and 0.39-0.41, respectively). The blood lead levels were significantly higher in boys and younger children (p<0.0001) and children with less educated fathers (p=0.004) after adjusting for covariates. Urinary cadmium level increased with age (p<0.0001). The median levels of blood mercury and urinary cadmium were much higher in Korean children and adolescents than those in their peers in Germany, the US, and Canada. Blood lead levels tended to decrease with increasing age and divergence between the sexes, particularly in the early teen years. Median levels of blood lead and urinary cadmium decreased since 2010. CONCLUSION: Sociodemographic factors, including age, sex, and father's education level were associated with environmental exposure to heavy metals in Korean children and adolescents. These biomonitoring data are valuable for ongoing surveillance of environmental exposure in this vulnerable population.

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

Deprivation indices have been widely used to evaluate neighborhood socioeconomic status and therefore examine individuals within their regional context. Although some studies on the development of deprivation indices were conducted in Korea, additional research is needed to construct a more valid and reliable deprivation index. Therefore, a new deprivation index, named the K index, was constructed using principal component analysis. This index was compared with the Carstairs, Townsend and Choi indices. A possible association between infant death and deprivation was explored using the K index. The K index had a higher correlation with the infant mortality rate than did the other three indices. The regional deprivation quintiles were unequally distributed throughout the country. Despite the overall trend of gradually decreasing infant mortality rates, inequalities in infant deaths according to the deprivation quintiles persisted and widened. Despite its significance, the regional deprivation variable had a smaller effect on infant deaths than did individual variables. The K index functions as a deprivation index, and we may use this index to estimate the regional socioeconomic status in Korea. We found that inequalities in infant deaths according to the time trend persisted. To reduce the health inequalities among infants in Korea, regional deprivation should be considered.

Disparities in Children's Blood Lead and Mercury Levels According to Community and Individual Socioeconomic Positions.

We aimed to examine the associations between blood lead and mercury levels and individual and community level socioeconomic positions (SEPs) in school-aged children. A longitudinal cohort study was performed in 33 elementary schools in 10 cities in Korea. Among a total of 6094 children included at baseline, the final study population, 2281 children followed-up biennially, were analyzed. The geometric mean (GM) levels of blood lead were 1.73 µg/dL (range 0.02-9.26) and 1.56 µg/dL (range 0.02-6.83) for male and female children, respectively. The blood lead levels were significantly higher in males, children living in rural areas, and those with lower individual SEP. The GM levels of blood mercury were 2.07 µg/L (range 0.09-12.67) and 2.06 µg/L (range 0.03-11.74) for males and females, respectively. Increased blood mercury levels were significantly associated with urban areas, higher individual SEP, and more deprived communities. The risk of high blood lead level was significantly higher for the lower individual SEP (odds ratio (OR) 2.18, 95% confidence interval (CI) 1.36-3.50 in the lowest educational attainment of the father), with a significant dose-response relationship observed after adjusting for the community SEP. The association between high blood lead levels and lower individual SEP was much stronger in the more deprived communities (OR 2.88, 95% CI 1.27-6.53) than in the less deprived communities (OR 1.40, 95% CI 0.76-2.59), and showed a significant decreasing trend during the follow-up only in the less deprived communities. The risk of high blood mercury levels was higher in higher individual SEP (OR 0.64, 95% CI 0.40-1.03 in the lowest educational attainment of the father), with a significant dose-response relationship noted. Significant decreasing trends were observed during the follow-up both in the less and more deprived communities. From a public health point-of-view, community level intervention with different approaches for different metals is warranted to protect children from environmental exposure.

Social inequality in birth outcomes in Korea, 1995-2008.

Social inequality in adverse birth outcomes has been demonstrated in several countries. The present study examined the separate and joint effects of parental education and work in order to investigate the causal pathways of social class effects on adverse birth outcomes in Korea. The occurrence of low birth weight, preterm births, and intrauterine growth retardation was examined among 7,766,065 births in Korea from 1995 to 2008. The effect of social inequality, as represented by parental education and work, was examined against adverse birth outcomes using multivariate logistic regression after controlling for other covariates. Parental education had the most significant and greatest effect on all three adverse outcomes, followed by parental work and employment, which had lesser effects. For adverse birth outcomes, the gap between educational levels increased steadily in Korea from 1995 to 2008. Throughout the analysis, the effect of maternal manual work on adverse birth outcomes was apparent in the study results. Given this evidence of social inequality in education and employment, social interventions should aim at more in-depth and distal determinants of health.

Social inequalities in life expectancy and mortality during the transition period of economic crisis (1993-2010) in Korea.

BACKGROUNDS: This study examines social inequalities in life expectancy and mortality during the transition period of the Korean economic crisis (1993-2010) among Korean adults aged 40 and over. METHODS: Data from the census and the national death file from the Statistics Korea are employed to calculate life expectancy and age-specific-death-rates (ASDR) by age, gender, and educational attainment for five years: 1993, 1995, 2000, 2005, and 2010. Absolute and relative differences in life expectancy and Age-Specific Death Rates by educational attainment were utilized as proxy measures of social inequality. RESULTS: Clear educational gradient of life expectancy was observed at age 40 by both sexes and across five time periods (1993, 1995, 2000, 2005, and 2010). The gradient became notably worse in females between 1993 and 2010 compared to the trend in males. The educational gradient was also found for ASDR in all five years, but it was more pronounced in working age groups (40s and 50s) than in elderly groups. The relative disadvantage of ASDR among working age Korean adults, both males and females, became substantially worse over time. CONCLUSIONS: Social inequalities in life expectancy and ASDR of the working age group across socioeconomic status over time were closely related to the widening of the social difference created by the macroeconomic crisis and the expansion of neo-liberalism in Korea.

Inequalities in childhood cancer mortality according to parental socioeconomic position: A birth cohort study in South Korea.

We sought to explore a possible association between higher parental socioeconomic position and lower child cancer mortality. We examined total cancer mortality as well as site-specific cancer mortality. We constructed a retrospective birth cohort by linking South Korean birth records to death records from 1995 to 2004. Parental socioeconomic position and birth characteristics were identified from the birth records. Parental education and occupation were examined as socioeconomic variables while sex, parental age, gestational age, birth weight, multiple birth, birth order, and the death of previous children were included as birth characteristics. Cancer deaths were identified from the death records. In total, 5711,337 births were analyzed, including 30,844,015 total person-years. The total number of deaths was 21,217, including 1102 children who died of cancer. Hazard ratios of cancer mortality according to parental socioeconomic position were calculated using a Cox proportional hazard analysis with adjustment for the birth characteristics. All socioeconomic measures except maternal occupation showed a significant inverse association with cancer mortality after adjusting for the birth characteristics. For paternal education, high school and middle school graduation or lower was associated with an increased hazard ratio of cancer mortality compared to university education or higher: 1.14 (1.00-1.29) and 1.29 (1.02-1.62), respectively. For maternal education, middle school graduation or lower was associated with a hazard ratio of 1.54 (1.21-1.95). For paternal occupation, manual work and economic inactivity were associated with increased hazard ratios as compared to non-manual work: 1.17 (1.02-1.34) and 1.34 (1.04-1.73), respectively. Inequalities were also found for leukemia and central nervous system tumors. The extent of the inequalities decreased after age 5, and only the 1-4-year-old group showed significant associations with parental socioeconomic position. We conclude that there is an inverse relationship between childhood cancer mortality and parental socioeconomic position in Korea.

Occupational lymphohematopoietic cancer in Korea.

The purpose of this study was to review the existing studies on lymphohematopoietic (LHP) cancer in Korea, estimate the prevalence of workers exposed to carcinogens, and determine the population attributable fraction (PAF) of leukemia. Two case series and 4 case reports were reviewed. Using official statistics, the prevalence of benzene exposure and ionizing radiation exposure was estimated. Based on the prevalence of exposure and the relative risk, The PAF of leukemia was calculated. Between 1996 and 2005, 51 cases of LHP cancer were reported from the compensation system. Greater than 50% of occupational LHP cancer was leukemia, and the most important cause was benzene. In a cohort study, the standardized incidence ratio was 2.71 (95% CI, 0.56-7.91). The prevalence of exposure was 2.5% and 2.2% in 1995 and 2000, respectively. Using the 1995 prevalence, 3.6-4.8% and 0.1% of cases with leukemia were attributable to benzene and ionizing radiation exposure, respectively, which resulted in 39.7-51.4 cases per year. Benzene is the most important cause of occupational leukemia in Korea. Considering the estimated PAF in this study, the annual number of occupational LHP cancer (51 cases during 10-yr period), might be underreported within the compensation system.

Trends in educational differentials in suicide mortality between 1993-2006 in Korea.

PURPOSE: This study aims to examine how inequalities in suicide by education changed during and after macroeconomic restructuring following the economic crisis of 1997 in South Korea. MATERIALS AND METHODS: Using Korea's 1995, 2000, and 2005 census data aggregately linked to mortality data (1993-2006), relative and absolute differentials in suicide mortality by education were calculated by gender and age among Korean population aged 35 and over. RESULTS: Average annual suicide mortality rates have steadily increased from 1993-1997 to 2003-2006 in almost all sociodemographic groups stratified by gender, age, and education. Based on the relative index of inequality (RII) and slope index of inequality (SII), educational differentials in suicide mortality generally increased over time in men and women aged 45 years+. Although RII did not increase with year among men and women aged 35 - 44 years, SII showed a significantly increasing trend in this age group. CONCLUSION: These worsening absolute inequalities in suicide mortality indicate that the governmental suicide prevention policy should be directed toward socially disadvantaged groups of the Korean population.

The extent and distribution of inequalities in childhood mortality by cause of death according to parental socioeconomic positions: a birth cohort study in South Korea.

It has been shown that childhood mortality is affected by parental socioeconomic positions; in this article, we investigate the extent and distribution of inequalities across major causes of childhood death. We built a retrospective birth cohort using individually linked national birth and death records in South Korea. 1,329,540 children were followed up to exact age eight from 1995 to 1996 and total observed person-years were 10,594,168.18. Causes of death were identified from death records while parental education, occupation and birth characteristics were identified from birth records. Survival analysis was performed according to parental socioeconomic positions. Cox proportional hazard analysis was done according to parental education and occupation with adjustment of birth characteristics such as sex, parental age, gestational age, birth weight, multiple birth, the number of total births, and previous death of children. Cumulative incidence of mortality by age was obtained through a competing-risk method in each cause according to maternal education. From these results, distribution of inequalities across major causes of death was calculated. In total, 7018 deaths occurred during the eight years and mortality rate was 66.24 per 100,000 person-years. External cause was the most common cause of death followed by congenital malformations, nervous system diseases, perinatal diseases, cancer, respiratory, cardiovascular, infectious and gastrointestinal diseases. For all-cause mortality, hazard ratios (HR) were 1.98 (95% CI: 1.83-2.13) for paternal education, 1.90 (1.75-2.07) for maternal education, 1.40 (1.33-1.47) for paternal occupation and 2.33(1.98-2.73) for maternal occupation (between middle school graduation or lower and university or more for education, between manual and non-manual for occupation). Mortality differentials were found in every cause of death. External cause, respiratory, cardiovascular and infectious diseases showed larger HR than all-cause mortality: 2.20 (1.90-2.56), 2.87 (2.02-4.08), 2.50 (1.67-3.75) and 2.12 (1.43-3.15) respectively according to maternal education. On the contrary, congenital malformations and cancer had smaller HR than all-cause mortality: 1.49 (1.22-1.82) and 1.43 (1.00-2.05) respectively according to maternal education. In all-cause mortality and most of the causes, cumulative incidence of mortality increased rapidly until one or two years after birth and then slowed down. But in external cause and cancer, cumulative incidence of mortality accumulated at a constant pace. Thus, inequalities in these causes of death consistently widened. External cause was the leading cause of overall inequalities and its proportion was 36-42% followed by congenital malformations, respiratory diseases etc. We conclude that there were inequalities of childhood mortality in every major cause of death. External cause was the leading cause of both all-cause mortality and overall inequalities. Public health interventions to reduce inequalities are necessary and external cause should be primarily considered.

[The proportional mortality ratios of specific-cause mortality by occupation and education among men aged 20-64 in Korea (1993-2004)].

OBJECTIVES: This study investigated the relationship of occupational class and educational background with proportional mortality ratios in Korea. METHODS: Mortality was investigated using the entire registered death data from 1993 to 2004, obtained from the Korean National Statistics Office. Proportional mortality ratios (PMRs) for specific diseases were calculated according to the occupational class and educational background of men aged 20-64. RESULTS: Manual workers were found to have higher PMRs for liver disease and traffic accidents, as did the lower educated group. Especially, this study showed trends of an increasing of the wide gap between lower and higher socioeconomic stati for liver disease, traffic accidents, diabetes mellitus and cerebral vascular disease. The mortality for cerebrovascular disease, diabetes mellitus, heart disease, traffic accident and liver disease showed increasing trends according to the calendar year for the lower than the higher social class. CONCLUSIONS: The specific conditions that had higher PMRs in the Korean lower social class were liver disease and traffic accidents. Especially, there was an increasing trend for a widening of the gap between manual and non-manual groups in relation to mortality from liver disease, diabetes mellitus and traffic accidents.

[The effects of the parents' social class on infant and child death among 1995-2004 birth cohort in Korea].

OBJECTIVES: To investigate the effect of parents' social class on infant and child mortality rates among the birth cohort, for the period of transition to and from the Koran economic crisis 1995-2004. METHODS: All births reported to between 1995 and 2004 (n=5,711,337) were analyzed using a Cox regression model, to study the role of the social determinants of parents in infant and child mortality. The results were adjusted for the parents' age, education and occupation, together with mother's obstetrical history. RESULTS: The crude death rate among those under 10 was 3.71 per 1000 births (21,217 deaths among 5,711,337 births) between 1995 and 2004. The birth cohorts from lower educated parents less than elementary school showed higher mortality rates compared with those from higher educated parents over university level (HR:3.0 (95% CI:2.8-3.7) for father and HR:3.4 (95% CI:3.3-4.5) for mother). The mother's education level showed a stronger relationship with mortality among the birth cohort than that of the fathers'. The gaps in infant mortality rates by parents' social class, and educational level became wider from 1995 to 2004. In particular, the breadth of the existing gap between higher and lower parents' social class groups has dramatically widened since the economic crisis of 1998. DISCUSSIONS: This study shows that social differences exist in infant and child mortality rates. Also, the gap for the infant mortality due to social class has become wider since the economic crisis of 1998.

[What is the origin of inequalities in work and health?].

There has been an enormous increasing trend of widening gap of social inequalities since economic crisis at the end of 1997 in Korea. Since then, Korean society has deteriorated in economic and social conditions; the unemployment rate, temporary or casual workers and absolute poverty have increased. This paper presents the origin of inequalities in work and health in Korea. The origin of inequalities in work begins with the relationship between the capitalist and labourers in the capitalist mode of production. The conception and execution are dissolved in the work process in the capitalist mode of production. Thus, captitalists become control over ther labour process from workers. An alienation of the work process from the workers. The distribution of work is the majour source if inequalities in many countries as well as Korea. This paper presents the increasing tendency of unhealthy states such as mortality, early death, morbidity, physical work load, workplace injury amongst the under-privileged: ordinary workers, unemployed people, casual workers and socially deprived people in Korea.