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

doi:10.1016/j.ypmed.2004.07.002

Preventive Medicine

Volume 40, Issue 4, April 2005, Pages 444-451

https://doi.org/10.1016/j.ypmed.2004.07.002 Get rights and content

Abstract

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.

Introduction

Socioeconomic status is commonly used as a proxy for environmental and lifestyle factors that relate to health status [1]. This approach initially attempted to identify biological causal relationships between environmental factors, lifestyle factors, and diseases. However, socioeconomic status has recently been recognized as a determinant of health, which is of relevance to the design of prevention strategies and health policies. Occupation, income, and education are often used as indices of socioeconomic status. However, previous reports have consistently shown that members of the higher socioeconomic group have better health status, regardless of the values of these indices [2], [3], [4], [5].

The primary example of health inequalities between socioeconomic groups is the contrast between rich and poor countries. There is a clear relationship between gross national product per capita and life expectancy [6]. The main reason for this trend is the direct association of poverty with malnutrition and infectious diseases, which results in a high burden of maternal, infant, and childhood diseases in poorer countries. However, even in developed countries in which infectious diseases are not dominant, chronic diseases and external causes of death are related to socioeconomic status [7].

Japan is one of the most affluent countries in terms of gross national income per capita and has the longest healthy life expectancy in the world [8]. In addition, wealth inequalities in Japan are thought to be lower than in other developed countries [6]. However, to our knowledge, few studies have examined the association between socioeconomic and health status in Japan. Therefore, it is of great importance to determine the impact of socioeconomic status on health among the Japanese population. This large cohort study, which involved a representative sample of the Japanese population from across the country, examined the association between educational level and the major causes of death in Japan.

Section snippets

Methods

The Japan Collaborative Cohort Study for the Evaluation of Cancer Risk (JACC Study) is sponsored by the Ministry of Education, Science, Sports and Culture of Japan. The details of this cohort study have been described previously [9], [10], [11], [12]. Briefly, a baseline survey was conducted between 1988 and 1990. The JACC study enrolled 127,477 apparently healthy inhabitants in these areas with completion of the questionnaire. Of 127,477 enrolled, 110,792 (46,465 men and 64,327 women), aged

Results

Table 1 lists selected baseline characteristics of the study subjects by sex and educational background. Subjects of both sexes who were educated to a high level were less likely to smoke cigarettes and more likely to consume alcohol. Office workers were more common in the highly educated group than in the group with a low level of education.

Table 2, Table 3 show that individuals of both sexes with a low level of education had an increased overall risk of death [RR = 1.16, 95% confidence

Discussion

Wealth inequality in Japan is lower than in other developed countries according to the Gini coefficient [15]. This coefficient is a measure of the income inequality in a society, the values of which range between 0 and 1, where 0 indicates perfect equality (that is, everybody has the same income) and 1 indicates perfect inequality (that is, one individual has all of the income and everybody else earns nothing). The World Development Report [8] listed the following Gini coefficients: 0.25 for

Acknowledgments

Grant sponsor: Ministry of Education, Science, Sports and Culture of Japan; 61010076, 62010074, 63010074, 1010068, 2151065, 3151064, 4151063, 5151069, 6279102, 11181101, 12218237.

The present investigators involved in the JACC study and their affiliations are as follows: Dr. Yoshiyuki Ohno (the present chairman of the Monbusho ECC), Dr. Akiko Tamakoshi (Secretary General of the Monbusho ECC), and Dr. Hideaki Toyoshima, Nagoya University Graduate School of Medicine; Dr. Mitsuru Mori, Sapporo

References (45)

C. Slater et al.
Behavior, lifestyle, and socioeconomic variables as determinants of health status: implications for health policy development
Am. J. Prev. Med.
(1985)
V.M. Shkolnikov et al.
Educational level and adult mortality in Russia: an analysis of routine data 1979 to 1994
Soc. Sci. Med.
(1998)
E. Backlund et al.
The shape of the relationship between income and mortality in the United States. Evidence from the National Longitudinal Mortality Study
Ann. Epidemiol.
(1996)
J.W. Lynch et al.
Childhood and adult socioeconomic status as predictors of mortality in Finland
Lancet
(1994)
Y. Fujino et al.
Prospective study of educational background and stomach cancer in Japan
Prev. Med.
(2002)
A. Kirschenbaum et al.
Well being, work environment and work accidents
Soc. Sci. Med.
(2000)
M.G. Marmot et al.
Do socioeconomic differences in mortality persist after retirement? 25 year follow up of civil servants from the first Whitehall study
BMJ
(1996)
World Bank. World Development Report 2000/2001: Attacking Poverty;...
M. Marmot
Introduction
World Bank. World Development Indicators 2003: World Bank;...

Y. Ohno et al.

Japan collaborative cohort study for evaluation of cancer risk sponsored by Monbusho (JACC study)

J. Epidemiol.

(2001)

H. Iso et al.

Perceived mental stress and mortality from cardiovascular disease among Japanese men and women: the Japan Collaborative Cohort Study for Evaluation of Cancer Risk Sponsored by Monbusho (JACC Study)

Circulation

(2002)

T. Mizoue et al.

Prospective study of screening for stomach cancer in Japan

Int. J. Cancer

(2003)

D.R. Cox et al.

Analysis of Survival Data

(1984)

SAS/STAT User's Guide, Release 6.03

(1988)

Measuring health inequalities: Gini coefficient and concentration index

Epidemiol. Bull.

(2001)

I. Kawachi

Income inequality and health

G.B. Rodgers

Income and inequality as determinants of mortality: an international cross-section analysis. 1979

Int. J. Epidemiol.

(2002)

A.E. Kunst et al.

The size of mortality differences associated with educational level in nine industrialized countries

Am. J. Public Health

(1994)

L. Kilander et al.

Education, lifestyle factors and mortality from cardiovascular disease and cancer. A 25-year followup of Swedish 50-year-old men

Int. J. Epidemiol.

(2001)

M. Bobak et al.

Determinants of adult mortality in Russia: estimates from sibling data

Epidemiology

(2003)

B.H. Dennis et al.

The association of education with coronary heart disease mortality in the USSR Lipid Research Clinics Study

Int. J. Epidemiol.

(1993)

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¹: See acknowledgments for the investigators (name and affiliation) involved in the JACC Study.

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

Abstract

Background.

Method.

Results.

Conclusions.

Introduction

Section snippets

Methods

Results

Discussion

Acknowledgments

Am. J. Prev. Med.

Soc. Sci. Med.

Ann. Epidemiol.

Lancet

Prev. Med.

Soc. Sci. Med.

Do socioeconomic differences in mortality persist after retirement? 25 year follow up of civil servants from the first Whitehall study

BMJ

Introduction

Japan collaborative cohort study for evaluation of cancer risk sponsored by Monbusho (JACC study)

J. Epidemiol.

Perceived mental stress and mortality from cardiovascular disease among Japanese men and women: the Japan Collaborative Cohort Study for Evaluation of Cancer Risk Sponsored by Monbusho (JACC Study)

Circulation

Prospective study of screening for stomach cancer in Japan

Int. J. Cancer

Analysis of Survival Data

SAS/STAT User's Guide, Release 6.03

Measuring health inequalities: Gini coefficient and concentration index

Epidemiol. Bull.

Income inequality and health

Income and inequality as determinants of mortality: an international cross-section analysis. 1979

Int. J. Epidemiol.

The size of mortality differences associated with educational level in nine industrialized countries

Am. J. Public Health

Education, lifestyle factors and mortality from cardiovascular disease and cancer. A 25-year followup of Swedish 50-year-old men

Int. J. Epidemiol.

Determinants of adult mortality in Russia: estimates from sibling data

Epidemiology

The association of education with coronary heart disease mortality in the USSR Lipid Research Clinics Study

Int. J. Epidemiol.