Socioeconomic differences in behavioural and biological risk factors: a comparison of a Japanese and an English cohort of employed men

The relationship between loneliness and blood glucose: a cross-sectional survey among Japanese

Recently, researchers have uncovered a correlation between loneliness and both the development and management of diabetes. Nevertheless, previous studies employing an unvalidated loneliness questionnaire impair result accuracy. Furthermore, this aspect has not been researched in the Japanese population. Therefore, this cross-sectional study analyzed data from the Kanagawa prospective "ME-BYO" Cohort Study (ME-BYO cohort) to investigate the correlation between loneliness, as measured by 20 items on the UCLA Loneliness Scale, and blood glucose levels. A total of 666 participants were included in the analysis, with a mean age of 54.1 years and a mean BMI of 23 kg/m2. Half of the participants had obtained an education level beyond high school. The mean household income and physical activity level were reported as 6.83 million Japanese yen and 12.3 METs-h/day, respectively. Model 1 of the linear regression analysis determined that there was no significant association between the loneliness scale and HbA1c (p = 0.512). After adjusting for age, gender, BMI (model 2), sitting time, physical activity level (model 3), housemates, household income, and final education (model 4), and controlling for social support, quality of life, and depression (model 5), the results showed no significant association, with a p-value of 0.823, 0.791, 0.792, and 0.816, respectively. Thus, the study found no link between loneliness and HbA1c in the high SES population. This finding contradicts previous results and may be attributed to the impact of population characteristics, SES status, or genetic backgrounds.

Birth cohort, sex and educational disparities in the trajectories of body mass index in Taiwan: a longitudinal study

Background

Taiwan has gone through rapid industrialization, urbanization and economic growth in the 20th and early 21st centuries. Therefore, the population has experienced significant changes in the physical and social environment during the life course, which may affect the overall adiposity. Our aim was to examine the age trajectories of height, weight and body mass index (BMI) in the Taiwanese population and to explore the influences of sex, birth cohort and education.

Methods

The sample comprised 572,358 residents between 20 and 94 years of age in Taiwan who attended at least one health examination during 1996 to 2017 in a cohort study. Repeated measures of body weight and height were collected using an auto-anthropometer. We conducted a series of linear mixed-effects growth curve models to examine the trajectory of height, weight, and BMI across the life course with stratification by sex.

Results

Age-related trajectories of BMI differed between men and women and stronger cohort effects were observed among men, with younger cohorts having higher BMI. After holding cohort and age variables constant, men with junior high or lower education were shorter, thinner and had higher BMI than men with university or higher education (effect sizes: − 3.138 cm, p < 0.001; − 2.277 kg, p < 0.001; 0.121 kg/m², p < 0.001, respectively). Women with junior high or lower education were shorter, heavier and had higher BMI than women with university or higher education (effect sizes: − 2.368 cm, p < 0.001; 2.417 kg, p < 0.001; 1.691 kg/m², p < 0.001, respectively). The educational disparities in BMI were found to be larger among women.

Conclusions

Our findings suggest that younger generations, especially men, and lower educational level individuals, particularly women, have increasing levels of BMI. The influence of age and cohort effects together with sex and educational disparities on adiposity should be highlighted when designing future interventions and policies regarding overweight and obesity.

Cultural and life style practices associated with low inflammatory physiology in Japanese adults

Japan is an exceptionally healthy East Asian country with extended longevity. In addition, the typical levels of several proinflammatory proteins, including both C-reactive protein (CRP) and interleukin-6 (IL-6), are often reported to be low when compared to American and European populations. This analysis determined if blood levels of CRP and IL-6 were associated with 4 cultural practices reflective of Japanese behavior and customs -- drinking tea, eating seafood, consuming vegetables, and partaking in relaxing baths regularly - among 382 adults living in Tokyo. Regression models controlled for demographic factors, adiposity (BMI), physical exercise, smoking, alcohol use, and chronic illness (e.g., diabetes). Consuming a Japanese diet was associated with significantly lower CRP and IL-6 levels. More frequent bathing was associated with lower IL-6, but not specifically predictive of low CRP. This study has confirmed prior evidence for low inflammatory activity in Japanese adults and its association with several behavioral practices common in Japan.

Mortality inequalities by occupational class among men in Japan, South Korea and eight European countries: a national register-based study, 1990-2015

BACKGROUND

We compared mortality inequalities by occupational class in Japan and South Korea with those in European countries, in order to determine whether patterns are similar.

METHODS

National register-based data from Japan, South Korea and eight European countries (Finland, Denmark, England/Wales, France, Switzerland, Italy (Turin), Estonia, Lithuania) covering the period between 1990 and 2015 were collected and harmonised. We calculated age-standardised all-cause and cause-specific mortality among men aged 35-64 by occupational class and measured the magnitude of inequality with rate differences, rate ratios and the average inter-group difference.

RESULTS

Clear gradients in mortality were found in all European countries throughout the study period: manual workers had 1.6-2.5 times higher mortality than upper non-manual workers. However, in the most recent time-period, upper non-manual workers had higher mortality than manual workers in Japan and South Korea. This pattern emerged as a result of a rise in mortality among the upper non-manual group in Japan during the late 1990s, and in South Korea during the late 2000s, due to rising mortality from cancer and external causes (including suicide), in addition to strong mortality declines among lower non-manual and manual workers.

CONCLUSION

Patterns of mortality by occupational class are remarkably different between European countries and Japan and South Korea. The recently observed patterns in the latter two countries may be related to a larger impact on the higher occupational classes of the economic crisis of the late 1990s and the late 2000s, respectively, and show that a high socioeconomic position does not guarantee better health.

Associations of education and income with heavy drinking and problem drinking among men: evidence from a population-based study in Japan

Background

Some studies in Western countries have suggested that education and income are differentially associated with different drinking patterns. This study aimed to examine the associations of education and income with heavy drinking and problem drinking among community-dwelling Japanese men.

Methods

A questionnaire survey was conducted in metropolitan areas in Japan from 2010 to 2011 among residents aged 25 to 50 years; valid responses were received from 2004 men. Drinking patterns were categorized as non-to-moderate drinking, non-problematic heavy drinking, and problem drinking. Multiple logistic regression analyses were conducted to determine whether educational attainment or income was associated with drinking patterns, after adjustment for age, marital status, working status, income/education, self-rated health, and psychological distress.

Results

The study population included 84.4% non-to-moderate drinkers, 8.9% non-problematic heavy drinkers, and 6.7% problem drinkers. Lower educational attainment (high school or less) was significantly associated with increased risks of both non-problematic heavy drinking (odds ratio [OR], 1.80; 95% confidence interval [CI], 1.21–2.67) and problem drinking (OR, 2.06; 95% CI, 1.34–3.16), compared with university education or higher. Lower income (lowest tertile) was significantly associated with a lower risk of non-problematic heavy drinking (OR, 0.66; 95% CI, 0.43–1.00), but not of problem drinking (OR, 0.80; 95% CI, 0.50–1.30), compared with the highest income tertile.

Conclusions

These findings indicate that education and income are differentially associated with alcohol drinking patterns among community-dwelling Japanese men.

Different socioeconomic backgrounds between hazardous drinking and heavy episodic drinking: Prevalence by sociodemographic factors in a Japanese general sample

BACKGROUND

Hazardous drinking (HD) and heavy episodic drinking (HED) constitute different types of alcohol-related harm. The socioeconomic status (SES) background of various alcohol consumption behaviors is not clear. The purpose of this study was to clarify existing SES differences between HD and HED.

METHODS

The 2013 national survey regarding alcohol use among Japanese adults was utilized. The results from 1193 men and 1503 women aged 20-64 years were included in the analysis. Education attainment, household income, marital status, working status, and occupation were adopted as SES determinants. Binomial logistic regression analysis was conducted to estimate the odds ratios (ORs) of HD and HED for each SES group.

RESULTS

ORs (95% confidence intervals) of HD were higher among persons with less education among both men [1.61 (1.18-2.20)] and women [1.78 (1.19-2.67)]. The OR of HED in men was significantly higher among those who belonged to high household income, were married, and managers or professionals. The OR of HED among women was higher in persons who were employed, as compared with those who engaged in housework. There were no correlations between HED and educational background.

CONCLUSIONS

This study showed that in Japan, a lower educational background for both men and women was associated with a higher risk for HD, while higher current SES for men and working women were associated with a higher risk for HED. It is necessary to recognize the SES differences between HD and HED to achieve a policy to reduce alcohol-related harm.

DO BIOMARKERS VARY BY SOCIAL CLASS, EDUCATION AND REGION AND IS MIGRATION IMPORTANT? EVIDENCE FROM A COHORT OF BRITISH ADULTS

The aim of this study was to test whether Body Mass Index (BMI), waist circumference, systolic and diastolic blood pressure, Forced Expiratory Volume (FEV1) and Peak Expiratory Flow (PEF) vary in relation to social class at birth and adulthood, educational level and region of residence, and also with inter-generational social, educational and regional mobility/migration. The study used 5702 adults (2894 males and 2718 females) from the longitudinal British National Child Development Study (all children born in England, Scotland and Wales during the first week in March 1958 with follow-up throughout childhood and adulthood, most recently at 55 years of age). In both sexes BMI and waist circumference tended to increase from social classes I+II to IV+V and higher social class was associated with higher mean FEV1 and PEF. Better-educated adults tended to have lower BMI and waist circumference, and higher mean FEV1 and PEF. Women from Wales had the highest mean BMI and waist circumference but the lowest mean PEF, while women in Scotland had the highest mean systolic blood pressure and the lowest mean FEV1. For men only, FEV1 and PEF showed regional variation and the lowest mean FEV1 was in Wales and the lowest PEF in Yorkshire & Humberside. Inter-generational social mobility was not found to be associated with any of the biomarkers, while educational mobility was related only to FEV1 and PEF. In both sexes, in unadjusted regression analysis regional migrant cohort members tended to have a lower mean BMI than sedentes. Regional male migrants also tended to have a lower waist circumference and a higher FEV1 and PEF than sedentes.

Nutritional correlates of monetary diet cost in young, middle-aged and older Japanese women

Studies in many Western countries have consistently shown that monetary diet cost is positively associated with diet quality, but this may not necessarily be the case in Japan. This cross-sectional study examined the nutritional correlates of monetary diet cost among 3963 young (all 18 years old), 3800 middle-aged (mean age 48 years) and 2211 older (mean age 74 years) Japanese women. Dietary intakes were assessed using a comprehensive self-administered diet history questionnaire for young and middle-aged women and a brief self-administered diet history questionnaire for older women. Monetary diet cost was estimated using retail food prices. Total vegetables, fish and shellfish, green and black tea, white rice, meat, fruit and alcoholic beverages contributed most (79–89 %) to inter-individual variation in monetary diet cost. Multiple regression analyses showed that monetary diet cost was negatively associated with carbohydrate intake, but positively with intakes of all other nutrients examined (including not only dietary fibre and key vitamins and minerals but also saturated fat and Na) in all generations. For food group intakes, irrespective of age, monetary diet cost was associated inversely with white rice and bread but positively with pulses, potatoes, fruit, total vegetables, fruit and vegetable juice, green and black tea, fish and shellfish, and meat. In conclusion, in all three generations of Japanese women and contrary to Western populations, monetary diet cost was positively associated with not only healthy dietary components (including fruits, vegetables, fish and shellfish, dietary fibre, and key vitamins and minerals), but also less healthy components (including saturated fat and Na).

Socioeconomic inequalities of cardiovascular risk factors among manufacturing employees in the Republic of Ireland: A cross-sectional study

Objectives: To explore socioeconomic differences in four cardiovascular disease risk factors (overweight/obesity, smoking, hypertension, height) among manufacturing employees in the Republic of Ireland (ROI). Methods: Cross-sectional analysis of 850 manufacturing employees aged 18–64 years. Education and job position served as socioeconomic indicators. Group-specific differences in prevalence were assessed with the Chi-squared test. Multivariate regression models were explored if education and job position were independent predictors of the CVD risk factors. Cochran–Armitage test for trend was used to assess the presence of a social gradient. Results: A social gradient was found across educational levels for smoking and height. Employees with the highest education were less likely to smoke compared to the least educated employees (OR 0.2, [95% CI 0.1–0.4]; p < 0.001). Lower educational attainment was associated with a reduction in mean height. Non-linear differences were found in both educational level and job position for obesity/overweight. Managers were more than twice as likely to be overweight or obese relative to those employees in the lowest job position (OR 2.4 [95% CI 1.3–4.6]; p = 0.008). Conclusion: Socioeconomic inequalities in height, smoking and overweight/obesity were highlighted within a sub-section of the working population in ROI.

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Exploring socioeconomic differences in four cardiovascular disease risk factors among manufacturing workers in Ireland.

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Cross-sectional study with 850 randomly selected employees aged 18–64 years.

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A social gradient was found across education levels for smoking and height.

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Employees with a higher education attainment were less likely to be hypertensive.

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Managers were more likely to be overweight or obese relative to the general working population.

Socioeconomic Status and the Trajectory of Body Mass Index Among Older Japanese: A Nationwide Cohort Study of 1987-2006

OBJECTIVES

This research analyzed the body mass index (BMI) level and rate of change, and their association with socioeconomic status among older Japanese adults.

METHODS

Data came from a national sample of over 4,800 Japanese adults aged 60 and older at baseline, with up to 7 repeated observations over a period of 19 years (1987-2006). Hierarchical linear modeling was used to analyze the intrapersonal and interpersonal differences in BMI.

RESULTS

Average BMI among older Japanese was 22.26 at baseline and decreased with an accelerating rate over time. Relative to those with less education, BMI among older Japanese with more education was lower and it declined linearly at a faster rate over time. In contrast, higher household income at baseline was associated with a higher level of BMI but similar rates of decline over time. Furthermore, we found no evidence for age variations in the SES-BMI linkage as predicted by prior investigators.

DISCUSSION

These findings provide new insights into the complex relationship between socioeconomic factors and BMI, and help to inform the design of health policies and interventions related to weight control among older adults with diverse socioeconomic backgrounds.

[Health inequalities and occupational health]

There has been an emergent issue of health inequalities in Japan. Tackling health inequalities has been put on the primary agenda in the revised national health promotion campaign, so called "Kenko-Nippon-21"(Healthy Japan 21), which was announced in 2012. Against the background of this social movement, the present article argues how occupational health can contribute to health inequality issue based on the knowledge of public health and social epidemiology.Firstly, we reviewed a brief sketch of health inequality at occupational settings including position, job, and employment status. Secondly, we de scribed a conceptual model of a causal pathway of occupational class and health, based on the idea of life-course approach, and models such as cumulative model, trigger model and latent effect/sensitive period model. Finally, we proposed that health impact assessment as a tool to mitigate health inequality related to occupational policy.

Negative emotions predict elevated interleukin-6 in the United States but not in Japan

Previous studies conducted in Western cultures have shown that negative emotions predict higher levels of pro-inflammatory biomarkers, specifically interleukin-6 (IL-6). This link between negative emotions and IL-6 may be specific to Western cultures where negative emotions are perceived to be problematic and thus may not extend to Eastern cultures where negative emotions are seen as acceptable and normal. Using samples of 1044 American and 382 Japanese middle-aged and older adults, we investigated whether the relationship between negative emotions and IL-6 varies by cultural context. Negative emotions predicted higher IL-6 among American adults, whereas no association was evident among Japanese adults. Furthermore, the interaction between culture and negative emotions remained even after controlling for demographic variables, psychological factors (positive emotions, neuroticism, extraversion), health behaviors (smoking status, alcohol consumption), and health status (chronic conditions, BMI). These findings highlight the role of cultural context in shaping how negative emotions affect inflammatory physiology and underscore the importance of cultural ideas and practices relevant to negative emotions for understanding of the interplay between psychology, physiology, and health.

Occupational class differences in body mass index and weight gain in Japan and Finland

Background

Occupational class differences in body mass index (BMI) have been systematically reported in developed countries, but the studies have mainly focused on white populations consuming a Westernized diet. We compared occupational class differences in BMI and BMI change in Japan and Finland.

Methods

The baseline surveys were conducted during 1998–1999 among Japanese (n = 4080) and during 2000–2002 among Finnish (n = 8685) public-sector employees. Follow-up surveys were conducted among those still employed, in 2003 (n = 3213) and 2007 (n = 7086), respectively. Occupational class and various explanatory factors were surveyed in the baseline questionnaires. Linear regression models were used for data analysis.

Results

BMI was higher at baseline and BMI gain was more rapid in Finland than in Japan. In Finland, baseline BMI was lowest among men and women in the highest occupational class and progressively increased to the lowest occupational class; no gradient was found in Japan (country interaction effect, P = 0.020 for men and P < 0.0001 for women). Adjustment for confounding factors reflecting work conditions and health behavior increased the occupational class gradient among Finnish men and women, whereas factors related to social life had no effect. No statistically significant difference in BMI gain was found between occupational classes.

Conclusions

The occupational class gradient in BMI was strong among Finnish employees but absent among Japanese employees. This suggests that occupational class inequalities in obesity are not inevitable, even in high-income societies.

A new theory-based social classification in Japan and its validation using historically collected information

Studies of health inequalities in Japan have increased since the millennium. However, there remains a lack of an accepted theory-based classification to measure occupation-related social position for Japan. This study attempts to derive such a classification based on the National Statistics Socio-economic Classification in the UK. Using routinely collected data from the nationally representative Comprehensive Survey of the Living Conditions of People on Health and Welfare, the Japanese Socioeconomic Classification was derived using two variables - occupational group and employment status. Validation analyses were conducted using household income, home ownership, self-rated good or poor health, and Kessler 6 psychological distress (n ≈ 36,000). After adjustment for age, marital status, and area (prefecture), one step lower social class was associated with mean 16% (p < 0.001) lower income, and a risk ratio of 0.93 (p < 0.001) for home ownership. The probability of good health showed a trend in men and women (risk ratio 0.94 and 0.93, respectively, for one step lower social class, p < 0.001). The trend for poor health was significant in women (odds ratio 1.12, p < 0.001) but not in men. Kessler 6 psychological distress showed significant trends in men (risk ratio 1.03, p = 0.044) and in women (1.05, p = 0.004). We propose the Japanese Socioeconomic Classification, derived from basic occupational and employment status information, as a meaningful, theory-based and standard classification system suitable for monitoring occupation-related health inequalities in Japan.

Associations of household expenditure and marital status with cardiovascular risk factors in Japanese adults: analysis of nationally representative surveys

Background

Socioeconomic inequalities in health and social determinants of health are important issues in public health and health policy. We investigated associations of cardiovascular risk factors with household expenditure (as an indicator of socioeconomic status) and marital status in Japan.

Methods

We combined data from 2 nationally representative surveys—the Comprehensive Survey of Living Conditions and the National Health and Nutrition Survey, 2003–2007—and analyzed sex-specific associations of household expenditure quartiles and marital status with cardiovascular risk factors, including obesity, hypertension, dyslipidemia, and diabetes, among 6326 Japanese adults (2664 men and 3662 women) aged 40 to 64 years.

Results

For men, there was no statistically significant association between household expenditure and cardiovascular risk factors. For women, lower household expenditure was significantly associated with obesity, hypertension, diabetes, and the presence of multiple risk factors: the ORs for the lowest versus the highest quartile ranged from 1.39 to 1.71. In a comparison of married and unmarried participants, the prevalence of cardiovascular risk factors was higher among married women and lower among married men.

Conclusions

Lower socioeconomic status, as indicated by household expenditure, was associated with cardiovascular risk factors in Japanese women. Socioeconomic factors should be considered in health promotion and prevention of cardiovascular disease.

Occupational class inequalities in behavioral and biological risk factors for cardiovascular disease among workers in medium- and small-scale enterprises

The aim of this cross-sectional study was to examine whether occupational class inequalities existed in the behavioral and biological risk factors for cardiovascular disease among workers in medium- and small-scale enterprises. We asked 1,900 enterprises in the Ishikawa prefecture who were users of an external heath check-up facility to supply anonymous individual data in 2009. The 446 enterprises consented to the invitation. The study population was 12,625 individuals (8,104 males and 4,521 females) 16-59 yr of age. We compared indices among occupational classes. The indices of lipid and glucose metabolism were used only for subjects 40-59 yr of age. The results of this study revealed occupational class inequalities in the prevalence of current smoking, heavy drinking and hypertension in men. These inequalities were more prominent among men in the younger age group than in the older age group. In men, the most disadvantaged occupational class was transportation workers, followed by laborers. Occupational class inequalities in smoking were also found among female workers. However, the influences of occupational class on obesity and indices of lipid or glucose metabolism were inconsistent. A strategy for health promotion that targets the disadvantaged population is necessary for the prevention of cardiovascular disease.

Soft drink, 100% fruit juice, and vegetable juice intakes and risk of diabetes mellitus

BACKGROUND & AIMS

Japan has experienced a jump in the diabetes prevalence rates. We want to examine whether increased intake of soft drink and juices have contributed to this jump.

METHODS

Participants were 27,585 Japanese men and women aged 40-59 years who had no prior history of diabetes. Intakes of soft drink, 100% fruit juice and vegetable juice were measured by a validated food frequency questionnaire. Odds ratios of type 2 diabetes over 5 and 10 years were estimated by using logistic regression.

RESULTS

A total of 484 men and 340 women reported newly diagnosed diabetes during 10 years. High soft drink intake was associated with increased risk of type 2 diabetes in women but not men; odds ratio (95% CI) for women with almost daily consumption versus non-consumers was 2.10 (1.23-3.59; P-trend = 0.004) and 1.79 (1.11-2.89; P-trend = 0.01) at 5 and 10 years, respectively. The association was evident in overweight, highly educated and premenopausal women, and women with blue collar job. Intakes of 100% fruit juice and vegetable juice were not associated with risk of type 2 diabetes for either gender (P-trend >0.05).

CONCLUSIONS

Soft drink but not pure juices consumption was associated with increased risk of type 2 diabetes in Japanese women.

Social and geographic inequalities in premature adult mortality in Japan: a multilevel observational study from 1970 to 2005

OBJECTIVES

To examine trends in social and geographic inequalities in all-cause premature adult mortality in Japan.

DESIGN

Observational study of the vital statistics and the census data.

SETTING

Japan.

PARTICIPANTS

Entire population aged 25 years or older and less than 65 years in 1970, 1975, 1980, 1985, 1990, 1995, 2000 and 2005. The total number of decedents was 984 022 and 532 223 in men and women, respectively.

MAIN OUTCOME MEASURES

For each sex, ORs and 95% CIs for mortality were estimated by using multilevel logistic regression models with 'cells' (cross-tabulated by age and occupation) at level 1, 8 years at level 2 and 47 prefectures at level 3. The prefecture-level variance was used as an estimate of geographic inequalities of mortality.

RESULTS

Adjusting for age and time-trends, compared with production process and related workers, ORs ranged from 0.97 (95% CI 0.96 to 0.98) among administrative and managerial workers to 2.22 (95% CI 2.19 to 2.24) among service workers in men. By contrast, in women, the lowest odds for mortality was observed among production process and related workers (reference), while the highest OR was 12.22 (95% CI 11.40 to 13.10) among security workers. The degree of occupational inequality increased in both sexes. Higher occupational groups did not experience reductions in mortality throughout the period and was overtaken by lower occupational groups in the early 1990s, among men. Conditional on individual age and occupation, overall geographic inequalities of mortality were relatively small in both sexes; the ORs ranged from 0.87 (Okinawa) to 1.13 (Aomori) for men and from 0.84 (Kanagawa) to 1.11 (Kagoshima) for women, even though there is a suggestion of increasing inequalities across prefectures since 1995 in both sexes.

CONCLUSIONS

The present findings suggest that both social and geographic inequalities in all-cause mortality have increased in Japan during the last 3 decades.

Association of income with symptoms, morbidities and healthcare usage among Japanese adults

OBJECTIVES

Socioeconomic inequalities in healthcare services are major public health and healthcare concerns. We have examined the association of income with symptoms, morbidities and healthcare usage in a national sample of the Japanese population.

METHODS

For this study, data compiled on 21,929 men and 24,620 women from the Comprehensive Survey of the Living Conditions of People on Health and Welfare in 2007 were assessed. Among the survey respondents with symptoms, we compared the prevalences of symptoms and treatments and the number of respondents who received treatments for 16 groups of symptoms and disorders according to household income, from the highest to the lowest, using the relative index of inequalities (RII). The RIIs were computed by age groups [25-59 years (young group) and 60+ years (senior group)].

RESULTS

People with lower incomes had higher prevalences of symptoms and treatments for most of the disorders examined. The RIIs of symptoms and treatments were 1.19 [95% confidence interval (CI) 1.09-1.31] and 1.04 (95% CI 0.93-1.16) for the young group and 1.69 (1.53-1.87) and 1.51 (1.36-1.67) for the senior group, respectively. In terms of treatment prevalence among those with symptoms, the RII was not significantly lower than 1.0 except for a few disorders in the young group.

CONCLUSIONS

Our results indicate that income inequalities can be related to the prevalences of various symptoms and morbidities in our Japanese sample population and that these inequalities were greater in the senior group than in the young group. Our results also suggest that lower income is not a substantial barrier to the use of healthcare services by older Japanese individuals, while it is related to lower healthcare usage by individuals of working age.

Population differences in proinflammatory biology: Japanese have healthier profiles than Americans

The pleiotropic cytokine, interleukin-6 (IL-6), has emerged as a key factor in the biology of aging and the physiology of inflammation. Yet much of what we know about the normal functioning of IL-6 has been generated primarily from research on European populations and Americans of European descent. Our analyses compared IL-6 levels in 382 middle-aged and older Japanese to the values found in 1209 Caucasian- and African-Americans from the Midlife in the United States survey (MIDUS). Across the life span from 30 to 80 years of age, mean IL-6 levels were strikingly lower in Japanese individuals. Significantly lower levels of C-reactive protein (CRP) and fibrinogen (FBG) provided confirmatory evidence for a population difference in proinflammatory activity. Because IL-6 release has been associated with obesity, differences in body mass index (BMI) were taken into consideration. Japanese had the lowest, and African-Americans had the highest overall BMIs, but significant group differences in IL-6 persisted even after BMI was included as a covariate in the analyses. Additional support for distinct variation in IL-6 biology was generated when systemic levels of the soluble receptor for IL-6 (sIL-6r) were evaluated. Serum sIL-6r was higher in Japanese than Americans, but was most notably low in African-Americans. Our cytokine data concur with national differences in the prevalence of age-related illnesses linked to inflammatory physiology, including cardiovascular disease. The findings also highlight the importance of broadening the diversity of people included in population studies of health and aging, especially given the relative paucity of information for some Asian countries and on individuals of Asian heritage living in the US.

Do biological measures mediate the relationship between education and health: A comparative study

Despite a myriad of studies examining the relationship between socioeconomic status and health outcomes, few have assessed the extent to which biological markers of chronic disease account for social disparities in health. Studies that have examined this issue have generally been based on surveys in wealthy countries that include a small set of clinical markers of cardiovascular disease. The availability of recent data from nationally representative surveys of older adults in Costa Rica and Taiwan that collected a rich set of biomarkers comparable to those in a recent US survey permits us to explore these associations across diverse populations. Similar regression models were estimated on three data sets - the Social Environment and Biomarkers of Aging Study in Taiwan, the Costa Rican Study on Longevity and Healthy Aging, and the Health and Retirement Study in the USA - in order to assess (1) the strength of the associations between educational attainment and a broad range of biomarkers; and (2) the extent to which these biomarkers account for the relationships between education and two measures of health status (self-rated health, functional limitations) in older populations. The estimates suggest non-systematic and weak associations between education and high risk biomarker values in Taiwan and Costa Rica, in contrast to generally negative and significant associations in the US, especially among women. The results also reveal negligible or modest contributions of the biomarkers to educational disparities in the health outcomes. The findings are generally consistent with previous research suggesting stronger associations between socioeconomic status and health in wealthy countries than in middle-income countries and may reflect higher levels of social stratification in the US. With access to an increasing number of longitudinal biosocial surveys, researchers may be better able to distinguish true variations in the relationship between socioeconomic status and health across different settings from methodological differences.

Excessive drinking and history of unemployment and cohabitation in Danish men born in 1953

BACKGROUND

Few studies exist on social inequality of excessive drinking in Denmark and differences seem to be less pronounced than in other European countries. The aims of this study were to investigate how history of employment and cohabitation is associated with excessive drinking and to study interaction between both.

METHODS

Birth-cohort study of 6112 Danish men born in 1953 with follow-up in 2004 on excessive drinking at age 51 years.

RESULTS

Excessive drinking (between 22 and 35 units of alcohol per week) differed little depending on history of unemployment and cohabitation. Risk of very excessive drinking (drinking >35 units of alcohol per week) increased with number of job losses-ranging from one job-loss [odds ratio (OR) 1.72, 95% confidence interval (CI) 1.39-2.14] to three or more job-losses (OR 2.48, 95% CI 1.75-3.52)--and duration of unemployment--ranging from 1 to 5 years (OR 1.34, 95% CI 1.11-1.63) to ≥10 years (OR 4.16, CI 3.13-5-53). Very excessive drinking was also associated with number of broken partnerships-ranging from one broken partnership (OR 1.43, 95% CI 1.16-1.77) to three or more broken partnerships (OR 2.69, 95% CI 2.03-3.55)--and with living alone for >5 years--ranging from 6 to 9 years (OR 1.73, 95% CI 1.30-2.29) to ≥10 years (OR 2.55, 95% CI 2.04-3.55). We found an interaction between the number of job-losses and of broken partnerships in relation to very excessive drinking.

CONCLUSIONS

Very excessive drinking is related to number of job-losses, broken partnerships, living alone and duration of unemployment.

Association of alcohol intake with the risk of malignant lymphoma and plasma cell myeloma in Japanese: a population-based cohort study (Japan Public Health Center-based Prospective Study)

Few studies have evaluated the association between alcohol intake and the risk of the lymphoid neoplasms malignant lymphoma (ML) and plasma cell myeloma (PCM) among Asian populations. We conducted a large-scale population-based cohort study of 95,520 Japanese subjects (45,453 men and 50,067 women; age 40-69 years at baseline) with an average 13 years of follow-up, during which a total of 257 cases of ML and 89 of PCM were identified. Hazard ratios and 95% confidence intervals were estimated using a Cox regression model adjusted for potential confounders. Alcohol intake of > or = 300 g/week was associated with a significantly lower risk of lymphoid neoplasms (hazard ratio, 0.60; 95% confidence interval, 0.37-0.98) than occasional drinking at a frequency of <1 day/month, and the trend for alcohol consumption was significant (P = 0.028). A similar trend was observed for the subcategories of ML, PCM, and non-Hodgkin lymphoma (NHL), albeit that the results were significant only for alcohol consumption at > or = 300 g/week in NHL patients, probably due to the small number of subjects in each category. In conclusion, we found that alcohol had an inverse association with the risk of lymphoid neoplasms, particularly the risk of NHL, among a Japanese population.

Neighborhood socioeconomic status in relation to dietary intake and insulin resistance syndrome in female Japanese dietetic students

OBJECTIVE

An increasing number of studies in Western countries have shown that living in a socioeconomically disadvantaged neighborhood is associated with unfavorable dietary intake patterns and health status. However, information on such neighborhood socioeconomic differences in diet and health among different cultural settings, including Japan, is limited. This cross-sectional study examined the association of neighborhood socioeconomic status (SES) with dietary intake and a summary score of the insulin resistance syndrome (IRS) in a group of young Japanese women.

METHODS

Subjects were 1081 female Japanese dietetic students aged 18 to 22 y residing in 295 municipalities in Japan. Neighborhood SES index was defined by seven municipal-level variables, namely unemployment, household overcrowding, poverty, education, income, home ownership, and vulnerable group, with an increasing index signifying increasing neighborhood socioeconomic disadvantage. Dietary intake was estimated using a validated, comprehensive self-administered diet-history questionnaire. Measurements of body mass index, systolic blood pressure, fasting high-density lipoprotein cholesterol, triacylglycerol, glucose, and insulin were combined into an IRS score, with an increasing score signifying increasing levels of components of the IRS.

RESULTS

Neighborhood SES index was not associated with most of the dietary variables, body mass index, high-density lipoprotein cholesterol, triacylglycerol, or glucose. However, neighborhood SES index was significantly positively associated with systolic blood pressure, insulin, and IRS score, after adjustment for potential confounding or mediating factors, including household SES, dietary, and lifestyle factors.

CONCLUSION

Neighborhood socioeconomic disadvantage was associated with unfavorable profiles of the IRS score, but not dietary intake, in a group of young Japanese women.

Occupational class and incidence rates of cardiovascular events in middle aged men in Japan

We investigated whether occupational class affects the incidence of cardiovascular events in Japanese factory workers. We prospectively evaluated 1,794 male workers aged 40-59, including 632 non-manual and 1,162 manual workers, employed in a metal products factory in Japan. The hazard ratios of stroke, myocardial infarction (MI) and cardiovascular events (combined stroke, MI and sudden cardiac death) for manual workers were compared with non-manual workers as estimated by the Cox proportional hazards regression model. Among the 1,794 workers, there were 60 cardiovascular events (32 cases of stroke, 23 cases of MI and 5 cases of sudden cardiac death) with an incidence rate of 3.14 per 1,000 person-years for cardiovascular events; 1.68 for stroke and 1.20 for MI. Blood pressure and HbA1c significantly increased the risk of stroke. Body mass index and total cholesterol significantly increased the risk of MI. However, occupational class was determined not to be a risk factor for cardiovascular events. The hazard ratios of stroke, MI and cardiovascular events for manual workers compared with non-manual workers were 0.97 (95%CI, 0.45-2.08), 0.73 (95%CI, 0.30-1.79) and 0.92 (95%CI, 0.53-1.61), respectively. Our study did not reveal significant occupational class inequalities in the rate of cardiovascular events. These findings are not in accordance with studies from other industrialized countries.

Socioeconomic inequalities in physical and mental functioning of British, Finnish, and Japanese civil servants: role of job demand, control, and work hours

This study aims to evaluate whether the pattern of socioeconomic inequalities in physical and mental functioning as measured by the Short Form 36 (SF-36) differs among employees in Britain, Finland, and Japan and whether work characteristics contribute to some of the health inequalities. The participants were 7340 (5122 men and 2218 women) British employees, 2297 (1638 men and 659 women) Japanese employees, and 8164 (1649 men and 6515 women) Finnish employees. All the participants were civil servants aged 40-60 years. Both male and female low grade employees had poor physical functioning in all cohorts. British and Japanese male low grade employees tended to have poor mental functioning but the associations were significant only for Japanese men. No consistent employment-grade differences in mental functioning were observed among British and Japanese women. Among Finnish men and women, high grade employees had poor mental functioning. In all cohorts, high grade employees had high control, high demands and long work hours. The grade differences in poor physical functioning and disadvantaged work characteristics among non-manual workers were somewhat smaller in the Finnish cohort than in the British and Japanese cohorts. Low control, high demands, and both short and long work hours were associated with poor functioning. When work characteristics were adjusted for, the socioeconomic differences in poor functioning were mildly attenuated in men, but the differences increased slightly in women. This study reconfirms the generally observed pattern of socioeconomic inequalities in health for physical functioning but not for mental functioning. The role of work characteristics in the relationship between socioeconomic status and health differed between men and women but was modest overall. We suggest that these differences in the pattern and magnitude of grade differences in work characteristics and health among the 3 cohorts may be attributable to the different welfare regimes among the 3 countries.

Social class differences in health behaviours among employees from Britain, Finland and Japan: the influence of psychosocial factors

This study aims to examine social class differences in smoking, heavy drinking, unhealthy food habits, physical inactivity and obesity, and work-related psychosocial factors as explanations for these differences. This is done by comparing employee cohorts from Britain, Finland and Japan. Social class differences in health behaviours are found in the two western European countries, but not in Japan. The studied psychosocial factors related to work, work-family interface and social relationships did not explain the found class differences in health behaviours.

Education, but not occupation or household income, is positively related to favorable dietary intake patterns in pregnant Japanese women: the Osaka Maternal and Child Health Study

Although a large body of epidemiologic data accumulated in Western countries show that individuals with a higher socioeconomic position consume higher quality diets, information on such socioeconomic differences in the diets of non-Western populations, including Japanese, is absolutely lacking. This cross-sectional study examined the association of socioeconomic position with dietary intake in a group of pregnant Japanese women. Subjects were 1002 Japanese women during pregnancy. Socioeconomic position was assessed by education, occupation, and household income. Dietary intake was estimated using a validated, self-administered, comprehensive diet history questionnaire. Education was associated positively with intake of protein; total n-3 and marine-origin n-3 polyunsaturated fatty acids; dietary fiber; cholesterol; potassium; calcium; magnesium; iron; vitamins A, D, E, and C; and folate 9 and inversely with that of carbohydrate. No associations were seen between education and intake of total fat; saturated, monounsaturated, and total and n-6 polyunsaturated fatty acids; alcohol; or sodium. Regarding food, higher education was associated with a higher intake of vegetables, fish and shellfish, and potatoes and lower intake of rice. Education was not associated with intake of bread, noodles, confectioneries and sugars, fats and oils, pulses and nuts, meat, eggs, dairy products, or fruit. For occupation, housewives had a higher intake of dietary fiber, magnesium, iron, vitamin A, folate, and pulses and nuts than working women. Household income was not associated with any nutrient or food examined. In conclusion, education, but not occupation or household income, was positively associated with favorable dietary intake patterns in a group of pregnant Japanese women.

Monetary Diet Cost is Associated with not only Favorable but also Unfavorable Aspects of Diet in Pregnant Japanese Women: The Osaka Maternal and Child Health Study

While several observational studies in European countries have shown that higher monetary diet cost is associated with healthier diets, information on the relationship of cost to diet quality in other countries is sparse, including Japan. This cross-sectional study examined the association between monetary diet cost and dietary intake in a group of pregnant Japanese women. Subjects were 596 pregnant Japanese housewives. Dietary intake was estimated using a validated, self-administered, comprehensive diet history questionnaire. Monetary diet cost was calculated using retail food prices. Values of monetary diet cost and nutrient and food intake were energy-adjusted using the density method. Monetary diet cost was associated positively with the intake of protein, total fat, saturated fatty acids, dietary fiber, cholesterol, sodium, potassium, calcium, magnesium, iron, vitamins A, D, E, C, and folate, and inversely with that of carbohydrate. For foods, cost was associated positively with the intake of potatoes, pulses and nuts, fish and shellfish, meat, dairy products, vegetables, and fruits, and inversely with that of rice and bread. No association was seen for noodles, confectioneries and sugars, fats and oils, or eggs. Cost was also associated inversely with dietary energy density. In conclusion, monetary diet cost was associated with not only favorable aspects of diet, including a higher intake of dietary fiber, key vitamins and minerals, fruits, and vegetables and lower dietary energy density, but also unfavorable aspects, including a higher intake of fat and sodium and lower intake of carbohydrate and rice, in a group of pregnant Japanese women.

Relationship of socioeconomic status to C-reactive protein and arterial stiffness in urban Japanese civil servants

This study investigates whether the two socioeconomic status indicators, educational level and employment grade, are associated with C-reactive protein (CRP) levels and arterial stiffness among Japanese urban civil servants. Brachial-ankle pulse-wave velocity (baPWV) as an indicator of arterial stiffness, CRP, occupational stress and conventional risk factors were evaluated in 3412 men and 854 women. Although the socioeconomic gradient showed a significant association with the CRP levels in men after adjustment for age, the significance disappeared after multivariate adjustment, whereas in women, the socioeconomic gradient showed no significant association with the CRP levels. In men, educational level was significantly associated with the baPWV value after adjustment for conventional risk factors, CRP and occupational stress (P for trend <0.0001). With regards to employment grade, only low-level non-manual workers had a significantly lower baPWV value as compared to manual workers at a fully adjusted model, and trend significance disappeared. However, in women, neither educational level nor employment grade was associated with the baPWV value. In summary, the socioeconomic gradient, especially the educational level, was significantly inversely related to the baPWV value in men. In women, the socioeconomic gradient was not related to the baPWV value. An inverse relationship between the socioeconomic gradient and CRP levels was found in men only after age adjustment. We suggest that because the educational level is an important aspect in the adolescent environment and hence might influence the future lifestyle, early health education should be provided to prevent an unfavourable lifestyle and atherosclerotic diseases in later life.

Associations of job strain and working overtime with adverse health behaviors and obesity: evidence from the Whitehall II Study, Helsinki Health Study, and the Japanese Civil Servants Study

Adverse health behaviors and obesity are key determinants of major chronic diseases. Evidence on work-related determinants of these behavioral risk factors is inconclusive, and comparative studies are especially lacking. We aimed to examine the associations between job strain, working overtime, adverse health behaviors, and obesity among 45-60-year-old white-collar employees of the Whitehall II Study from London (n=3,397), Helsinki Health Study (n=6,070), and the Japanese Civil Servants Study (n=2,213). Comparable data from all three cohorts were pooled, and logistic regression analysis was used, stratified by cohort and sex. Models were adjusted for age, occupational class, and marital status. Outcomes were unhealthy food habits, physical inactivity, heavy drinking, smoking, and obesity. In London, men reporting passive work were more likely to be physically inactive. A similar association was repeated among women in Helsinki. Additionally, high job strain was associated with physical inactivity among men in London and women in Helsinki. In London, women reporting passive work were less likely to be heavy drinkers and smokers. In Japan, men working overtime reported less smoking, whereas those with high job strain were more likely to smoke. Among men in Helsinki the association between working overtime and non-smoking was also suggested, but it reached statistical significance in the age-adjusted model only. Obesity was associated with working overtime among women in London. In conclusion, job strain and working overtime had some, albeit mostly weak and inconsistent, associations with adverse health behaviors and obesity in these middle-aged white-collar employee cohorts from Britain, Finland, and Japan.

Cigarette smoking and tooth loss experience among young adults: a national record linkage study

Background

Various factors affect tooth loss in older age including cigarette smoking; however, evidence regarding the association between smoking and tooth loss during young adulthood is limited. The present study examined the association between cigarette smoking and tooth loss experience among adults aged 20–39 years using linked data from two national databases in Japan.

Methods

Two databases of the National Nutrition Survey (NNS) and the Survey of Dental Diseases (SDD), which were conducted in 1999, were obtained from the Ministry of Health, Labor and Welfare with permission for analytical use. In the NNS, participants received physical examinations and were interviewed regarding dietary intake and health practices including cigarette smoking, whereas in the SDD, participants were asked about their frequency of daily brushing, and received oral examinations by certified dentists. Among 6,805 records electronically linked via household identification code, 1314 records of individuals aged 20 to 39 years were analyzed. The prevalence of 1+ tooth loss was compared among non-, former, and current smokers. Multiple logistic regression models were constructed including confounders: frequency of tooth brushing, body mass index, alcohol consumption, and intake of vitamins C and E.

Results

Smoking rates differed greatly in men (53.3%) and women (15.5%). The overall prevalence of tooth loss was 31.4% (31.8% men and 31.1% women). Tooth loss occurred more frequently among current smokers (40.6%) than former (23.1%) and non-smokers (27.9%). Current smoking showed a significant association with 1+ tooth loss in men (adjusted OR = 2.21 [1.40–3.50], P = 0.0007) and women (1.70 [1.13–2.55], P = 0.0111). A significant positive exposure-related relationship between cigarette smoking status and tooth loss was observed (P for trend < 0.0001 and 0.0004 in men and women, respectively). Current smoking was also associated with the prevalence of decayed teeth (1.67 [1.28–2.20], P = 0.0002).

Conclusion

An association between cigarette smoking and tooth loss was evident among young adults throughout Japan. Due to limitations of the available variables in the present databases, further studies including caries experience and its confounders should be conducted to examine whether smoking is a true risk of premature tooth loss in young adults.

Different income information as an indicator for health inequality among Japanese adults

BACKGROUND

There are several alternative indicators of income information, which is a fundamental measure of individual socioeconomic position. In this study, we compared the degrees of associations of four types of income information with health variables among Japanese adults.

METHODS

Using a nationally representative sample of 29,446 men and 32,917 women aged 20 years and over, the associations between four income indicators and health variables were examined using the odds ratio in logistic regression analysis and the concentration index by sex and age group (20-59 years and 60+ years). Income indicators consisted of total household income, equivalent household income, total household expenditure, and equivalent household expenditure. Current smoking and self-rated health statuses were used as health variables.

RESULTS

A low income was associated with a high prevalence of smoking and fair/poor self-rated health, with some differences among sex and age groups and income indicators, but less difference among methods of statistical analyses. Total and equivalent incomes were similarly and more markedly associated with smoking and self-rated health statuses, whereas equivalent expenditure showed the smallest degree of health difference. For the population aged 60+ years, the degree of health differences in smoking was similar between income and expenditure.

CONCLUSIONS

Although the degree of income-related health differences is dependent on health outcome and both sex and age group, this study suggests that either crude or equivalent household income is a useful indicator for health inequality among Japanese adults.

Do biomarkers of stress mediate the relation between socioeconomic status and health?

OBJECTIVES

To test the relation between socioeconomic status (SES) and biomarkers of chronic stress, including basal cortisol, and to test whether these biomarkers account for the relation between SES and health outcomes.

DESIGN

Cross sectional study using data from the 2000 social and environmental biomarkers of aging study (SEBAS).

SETTING

Taiwan.

PARTICIPANTS

Nationally representative sample of 972 men and women aged 54 and older.

MAIN OUTCOME MEASURES

Highest risk quartiles for 13 biomarkers representing functioning of the neuroendocrine system, immune/inflammatory systems, and the cardiovascular system: cortisol, adrenaline (epinephrine), noradrenaline (norepinephrine), serum dihydroepiandrosterone sulphate (DHEA-S), insulin-like growth factor 1 (IGF1), interleukin 6 (IL6), albumin, systolic blood pressure, diastolic blood pressure, waist-hip ratio, total cholesterol-HDL ratio, HDL cholesterol, and glycosylated haemoglobin; self reported health status (1-5) and self reported mobility difficulties (0-6).

RESULTS

Lower SES men have greater odds of falling into the highest risk quartile for only 2 of 13 biomarkers, and show a lower risk for 3 of the 13 biomarkers, with no association between SES and cortisol. Lower SES women have a higher risk for many of the cardiovascular risk factors, but a lower risk for increased basal readings of adrenaline, noradrenaline, and cortisol. Inclusion of all 13 biological markers does not explain the relation between SES and health outcomes in the sample.

CONCLUSIONS

These data do not support the hypothesis that chronic stress, via sustained activation of stress related autonomic and neuroendocrine responses, is an important mediator in the relation between SES and health outcomes. Most notably, lower SES is not associated with higher basal levels of cortisol in either men or women. These results place an increased burden of proof on researchers who assert that psychosocial stress is an important pathway linking SES and health.

Psychosocial work characteristics and sickness absence in Japanese employees

OBJECTIVES

This study was undertaken to examine the association between sickness absence in Japanese employees and job demand/control and occupational class as psychosocial work characteristics.

METHODS

The study was cross-sectional in design with data collected from 20,464 male and 3,617 female employees, whose mean age was 40.9 years (SD +/- 9.1 years) and 36.9 years (SD +/- 10.8 years), respectively. The participants were asked to write the total number of sick leaves they had taken during the past year, and a comparison was made between the group with more than 6 days of sickness absence and the group with 0-6 days as a reference group. Job demands, job control, and worksite support from supervisors and colleagues were analyzed by the Job Content Questionnaire, and likewise by the Generic Job Stress Questionnaire of the National Institute for Occupational Safety and Health.

RESULTS

Both low job control and low support at the worksite were associated with a high frequency of sickness absence. But there was no clear relationship between job demands and sickness absence. The lowest sickness absence rate was found in male managers and the highest in male and female laborers.

CONCLUSION

This is the first report of a large-scale survey of Japanese employees to show a high frequency of sickness absence associated with increased work stress and a socioeconomically low occupational class.

Comparison of brachial-ankle pulse wave velocity in Japanese and Russians

Pulse wave velocity (PWV) is a well-known indicator of arterial stiffness and a marker of the presence of vascular lesions. Cardiovascular mortality in Russia has become the highest in the world. The Japanese are enjoying long lives, and the mortality caused by cardiovascular diseases has thus far remained at lower levels than that in Russia. In this study, we focused on brachial-ankle pulse wave velocity (baPWV) obtained from normal human subjects in Russia as well as in Japan, and compared their respective cardiovascular risks. We evaluated baPWV in 337 Japanese and 138 Russian healthy subjects. The baPWV was recorded using a PWV diagnosis device. BaPWV was measured between 2 locations of the arterial tree. The baPWV in the Russian group was significantly higher than that obtained in the Japanese of two groups categorized by age (40-59 years and 60- years). Further, body mass index (BMI), systolic blood pressure (SBP) and diastolic blood pressure in the Russian group were significantly higher than those obtained in Japanese in three age groups (under 39 years, 40-59 years, and 60- years). Moreover, the baPWV indicated a positive correlation with age, BMI and SBP in both Japanese and Russians, although the increasing trend of the baPWV against age of the Russian group had a larger value than that of the Japanese. Therefore, we suggest that arterial stiffness might be promoted earlier in the Russian group, which might be the main cause of the increased cardiovascular risk in Russia.

Factors explaining disability-free life expectancy in Japan: the proportion of older workers, self-reported health status, and the number of public health nurses

BACKGROUND

Disability-free life expectancy (DFLE) data for 47 prefectures in Japan were reported in 1999; however, few studies have identified the factors associated with the length of the DFLE. The objective of this study was to elucidate the primary factors that explain differences in DFLEs in Japan.

METHODS

In our ecological study, 47 prefectures in Japan were used as units of analysis. The DFLEs for men and women at 65 years of age (DFLE65), calculated by Hashimoto et al using Sullivan's method, were set as dependent variables. From various national surveys, 181 factors associated with demographics, socioeconomic status, health status and health behaviors, medical environment, social relationships, climate, and other areas were gathered as independent variables. Pearson's or Spearman's correlation coefficients were calculated to screen independent variables potentially associated with the DFLE65s. Then, multivariate linear regression analyses were conducted for the selected 24 independent variables after adjusting for the proportion of older people (65 years or more) and population density.

RESULTS

Multivariate linear regression analyses revealed that the large number of public health nurses per 100,000 population, a good self-reported health status, and a high proportion of older workers were significantly associated with long DFLE65s for both genders.

CONCLUSIONS

These three factors could potentially explain the differences in DFLE of the older population in Japan.

Socioeconomic pattern of smoking in Japan: income inequality and gender and age differences

PURPOSE

To elucidate the influence of individual socioeconomic status on smoking in Japanese adults.

METHODS

Using a nationally representative sample (20,206 men and 21,093 women aged 18 to 54 years), the relation between smoking and socioeconomic characteristics was analyzed by sex and age group (18 to 24, 25 to 39, and over 40 years).

RESULTS

The smoking prevalence was 57.0% for men and 16.6% for women. Living in an urban area was a negative factor for smoking in men, while a positive factor in women. Being married was positively associated with smoking in the younger population, but negatively associated in the older population. A relation between lower income and smoking was found in all groups, except in men aged 18 to 24 years. The income-related difference was most pronounced in the population aged 25 to 39 years: OR of smoking for the highest income quintile compared with the lowest was 0.60 (95% CI, 0.51-0.71) for men and 0.29 (95% CI, 0.23-0.35) for women.

CONCLUSIONS

Socioeconomic status, especially income, substantially predicted smoking in the Japanese population, while the impact differed according to sex and age groups. Effective anti-smoking strategies require consideration of the gender and age differences in the socioeconomic pattern of smoking.

A nationwide cohort study of educational background and major causes of death among the elderly population in Japan

BACKGROUND

This prospective cohort study examined the association between educational level and major causes of death in Japan.

METHOD

A baseline survey was conducted between 1988 and 1990 among 110,792 inhabitants of 45 areas aged 40-79 years. Follow-up surveys were conducted annually and causes of death were identified from death certificates. The analysis was restricted to 16,715 men and 23,284 women.

RESULTS

During the follow-up period (377,139 person-years), 6628 deaths were recorded. Individuals with low levels of education had an increased overall risk of death [relative risk (RR)=1.16, 95% confidence interval (CI): 1.08, 1.25, in men; RR=1.26, 95% CI: 1.14, 1.39, in women], cancers (RR=1.17, 95% CI: 1.04, 1.32, in men; RR=1.10, 95% CI: 0.93, 1.30, in women), and death from external causes (RR=1.81, 95% CI: 1.29. 2.54, in men; RR=1.78, 95% CI: 1.18, 2.70, in women). Ischemic heart disease risk was marginally reduced in men with low levels of education (RR=0.77, 95% CI: 0.58, 1.01).

CONCLUSIONS

These results show that health inequalities exist in Japan, even though wealth inequalities are relatively low. Social and political initiatives will be needed to correct these inequities between different socioeconomic statuses.

Explaining socioeconomic inequality in mortality among South Koreans: an examination of multiple pathways in a nationally representative longitudinal study

BACKGROUND

South Korea has a different cause-specific structure of mortality compared with North America and northern European countries where studies on pathways to socioeconomic mortality inequalities have been performed. We examined the ability of multiple pathways to explain socioeconomic differentials in all-cause mortality in South Korea.

METHODS

The 1998 National Health and Nutrition Survey data of South Korea were linked to data on mortality. The socioeconomic position (SEP) indicator was household income. Twelve variables represented biological risk factors (body mass index, systolic blood pressure, cholesterol, and glucose), health behaviours (smoking, alcohol consumption, and regular exercise), psychosocial factors (feelings of sadness and depression, perceived level of stress, and marital status), and early life exposures (education and adulthood height).

RESULTS

Mortality differentials by income level did not decrease after exclusion of subjects with severe chronic illness or functional limitation. Biological risk factors, health behaviours, and psychosocial factors caused minor reductions in relative risk for income levels. The ability of early life exposures to explain socioeconomic differentials in mortality was greater than that of biological risk factors, health behaviours, and psychosocial factors.

CONCLUSIONS

The contribution of multiple pathways to socioeconomic differentials in all-cause mortality may vary in place with the different cause-specific structure of mortality. Future studies with specific pathway variables and specific disease outcomes would provide better understanding of causal mechanisms between SEP and health.

Interfaces between cardiovascular and kidney disease among Aboriginal Australians

Rates of kidney disease among several indigenous groups have been shown to be substantially higher than corresponding non-indigenous groups. This excess has been clearly shown among Aboriginal Australians with respect to both end-stage kidney disease and early kidney disease. Rates of cardiovascular disease among Aboriginal Australians are also very high, as are rates of diabetes, smoking, and possibly overweight and obesity. These factors have been traditionally linked with cardiovascular and renal disease as part of a broader "metabolic syndrome." However, the links and interfaces between cardiovascular and kidney disease in this environment extend beyond these "traditional" factors. The factors associated with atherosclerosis have expanded in recent years to include markers of inflammation, some infection, antioxidants, and other "non-traditional" risk factors. Given the high rates of acute infection and poor living conditions endured by many indigenous people, one might expect these "non-traditional" risk factors to be highly prevalent. In this review, we explore the relationships between markers of inflammation, some serological markers of infection, and other selected markers and both cardiovascular and renal disease. In doing so, we demonstrate links between kidney and cardiovascular disease at a number of levels, beyond the "traditional" cardiovascular/renal risk factors. Many of these factors are beyond the control of the individual or even community; addressing these issues a broader focus and biopsychosocial model.

A comparison of socioeconomic differences in physical functioning and perceived health among male and female employees in Britain, Finland and Japan

We compared the pattern of socioeconomic inequalities in physical functioning and perceived health among male and female employees in Britain, Finland and Japan. Participants were male and female public sector employees in Britain, Finland and Japan, who were economically active and 40-60 year-olds at the time of data collection. We measured perceived health and physical functioning (SF-36 physical component summary) with standardized health questionnaires. The results obtained here reconfirm the similarity of the patterns of ill-health of those with lower socioeconomic status among non-manual men and women in Britain and Finland. These data also provide good evidence for a socioeconomic gradient in ill-health among Japanese non-manual men, although this gradient was less systematic. For Japanese men poorer health of manual workers as compared to non-manual workers was well demonstrated. However, among Japanese women socioeconomic differences in health were small and inconsistent. In conclusion, Britain, Finland and Japan--representing 'liberal', 'Nordic' and 'conservative' welfare state regimes--produce broadly similar patterns of socioeconomic differences in health among men. However, different patterns of labour force participation and welfare provision in different welfare regimes may bring about different patterns of socioeconomic differences in health for working women. This is exemplified by the lack of health inequalities among employed Japanese women.

Effects of socioeconomic indicators on coronary risk factors, self-rated health and psychological well-being among urban Japanese civil servants

In Japan, the effects of socioeconomic indicators on coronary risk factors and subjective well-being in an urban population have not been compared. The subjects of this study were 1361 civil servants (968 men and 393 women, aged 35-64 years) working in an urban area of Japan. Screening examinations were conducted from April 1997 to March 1998, and a questionnaire survey was conducted in February 1998. The effects of two socioeconomic indicators, education level (junior high school, high school and university education) and employment grade (manual, low-level nonmanual and high-level nonmanual work), on behavioral and biological coronary risk factors, self-rated health and affect balance were investigated using multivariate logistic regression analyses. Smoking was found to be inversely associated with level of education; compared to university graduates, the odds ratios for subjects who had only graduated from high school and those for subjects who had only graduated from junior high school were 1.96 and 2.07 in men and 3.44 and 5.48 in women, respectively. As for alcohol drinking and physical inactivity, relationships were inconsistent in terms of direction by the two indicators. Among biological risk factors, diabetes was inversely associated with education level in men. Self-rated health, however, was inversely associated with employment grade both in men and women, and affect balance was inversely associated with employment grade in men. In summary, different effects of two socioeconomic indicators, education and employment grade, were seen in some coronary risk factors and subjective well-being in an urban Japanese population. Our findings should contribute to the elucidation of mechanisms of the socioeconomic gradients of risk factors and mortality from coronary heart disease in Japan.

Occupational Class and Exposure to Job Stressors among Employed Men and Women in Japan

BACKGROUND: The relationship between occupational class and exposure to job stressors among employed men and women in Japan remains unclear.

METHODS: Data of 16,444 men and 3,078 women were analyzed. The information was obtained from answers to a questionnaire distributed among employees of nine companies in Japan between 1996 and 1998 (average response rate, 85%). The International Standardized Classification of Occupations was used to classify respondents into eight occupational categories. The Job Content Questionnaire was used to measure job demands, job control, worksite support, and job insecurity. The associations between occupational class and job stressors, as well as job strain, were examined controlling for age, education, marital status, chronic medical condition, and personality traits, such as neuroticism and extraversion.

RESULTS: Men and women in high-class occupations (e.g., managers and professionals) had significantly greater job control, while job demands and worksite social support were not greatly different among occupations. A clear occupational class gradient in job insecurity was observed in women. A greater prevalence of high job strain was observed in low-class occupations compared to high-class occupations in both men and women. The occupational class gradient in job strain was greater for women. These patterns did not change after controlling for other covariates.

CONCLUSION: The present study suggests an occupational class gradient in job strain for employed men and women in Japan. Japanese women workers may have a greater occupational class gradient in job strain and job insecurity than men.