Elsevier

Public Health

Volume 121, Issue 3, March 2007, Pages 163-173
Public Health

Original Research
Higher mortality in areas of lower socioeconomic position measured by a single index of deprivation in Japan

https://doi.org/10.1016/j.puhe.2006.10.015Get rights and content

Summary

Objectives

To formulate an index representing area deprivation and elucidate the relation between the index and mortality in Japan.

Study design

Ecological study for prefectures (N=47) and municipalities (N=3366) across Japan.

Methods

Based on socioeconomic indicators of seven domains of deprivation (i.e. unemployment, overcrowding, low social class and poverty, low education, no home ownership, low income and vulnerable group), an index was formulated using the z-scoring method. The relation between the index and mortality was examined by correlation analysis, hierarchical Poisson regression and comparison of standardized mortality ratio according to the index.

Results

The deprivation index ranged from −7.48 to 10.98 for prefectures and from −16.97 to 13.82 for municipalities. The index was significantly positively correlated with prefectural mortality, especially in the population aged under 74 years: r=0.65 for men and r=0.41 for women. At the municipal level, hierarchical Poisson regression showed a significant positive coefficient of the index to mortality for both men and women, and excess mortality in the most deprived fifth compared to the least deprived fifth was 26.4% in men and 11.8% in women.

Conclusions

We formulated a deprivation index, which was substantially related to mortality at the prefectural and municipal levels. This study highlights the higher risk of dying among populations in socially disadvantaged areas and encourages the use of indices representing area socioeconomic conditions for further studies of area effects on health.

Introduction

As well as individual socioeconomic status such as social class, educational attainment and income, area characteristics have been focused on independent and critical determinants of population health.1, 2, 3 Previous studies showed that socially disadvantaged areas had higher mortality, morbidity and prevalence of health risk behaviour.4, 5, 6, 7, 8

Measurement of area socioeconomic condition, in particular, ‘deprivation’, is a critical matter in examining the relation between area characteristics and health. Deprivation is generally defined as a state of observable and demonstrable disadvantage related to the local community or the wider society or nation to which an individual, family or group belongs.9 Deprivation indices have a long history in the UK, where several traditional indices such as Townsend, Jarman and Carstairs have been developed and commonly used.10 This was followed by a number of studies for the development and use of deprivation indices in many countries including not only European countries but also Australia, Canada, New Zealand, the US, and others.11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 These indices were formulated at various administrative levels with multiple indicators mainly from census data, comprising multiple domains such as unemployment, low social class, low educational attainment, household overcrowding, and home ownership. These deprivation indices have been applied in funding formulas, resource allocation and research in a variety of settings such as health and other social services.16, 26

In Japan also, the relation between health level and area characteristics has been elucidated. Recent systematic studies using municipal data regarding all causes and cause-specific mortality along with several socioeconomic indicators showed significant relationships between regional mortality and socioeconomic characteristics.27, 28

There have been some efforts to formulate indices of area social characteristics in Japan, mainly representing wealth rather than deprivation, although these indices have not received consensus and are not used in epidemiologic and public health research.29 Instead of established indices, indices formulated from limited socioeconomic indicators using factorial analysis were used in previous studies, and a substantial relation between these indices and mortality was found.27, 30 However, the dimensions of socioeconomic disadvantage were not integrated into a single index, and the formulated indices appeared to represent not only socioeconomic disadvantage but also other area characteristics such as urban–rural difference.27, 28

Health inequalities in relation to socioeconomic factors have been of great interest in public health.31, 32 Examining health inequalities in Japan will provide important insights in this field, because the Japanese population shows the healthiest status in the world,33, 34 and it is suggested that relatively smaller socioeconomic disparities partly contributes to this excellent health level.35, 36 The development of an index representing socioeconomic disadvantage would stimulate the study of health inequalities in Japan. The present study formulated an index of area deprivation, which included critical domains of social disadvantage and was available for small area analyses, and examined the relation between the index and mortality at the levels of prefecture and municipality.

Section snippets

Units of analyses

The study units of this study were prefecture and municipality. Local public entities in Japan are divided into two categories: the first consists of municipalities (i.e. cities, towns and villages), while the second consists of prefectures. All districts in the country belong to one of the municipalities and fall within the boundaries of one of 47 prefectures. Tokyo prefecture (Tokyo Metropolis) includes 23 special wards (‘ku’) in addition to cities, towns and villages. Twelve large cities

Results

The age-adjusted mortality rate (per 100,000) of the 47 prefectures ranged from 579.4 to 756.1 for men and 286.9 to 347.7 for women in the total population, and 312.0 to 442.4 for men and 139.0 to 175.2 for women in the population aged under 75. The correlations between mortality and the original indicators in the deprivation index both for prefectural and municipal analyses are summarized in Appendix B.

The deprivation index calculated using the z-scoring method (DIz) by prefecture ranged from

Discussion

We formulated deprivation indices using multiple socioeconomic indicators at the prefectural and municipal levels in Japan, and examined the relation between the indices and mortality. The formulated deprivation indices were significantly related to higher mortality at both levels, especially for men and premature mortality.

Selection of indicators and the method of index formulation are critical matters in this study. Indicator selection was based on the main domains of established indices in

Acknowledgment

This study was supported by a Grant-in-Aid for Scientific Research by the Japan Society for the Promotion of Science (Grant nos. 14570326 and 16590497).

References (56)

  • A.V. Diez Roux et al.

    Neighborhood of residence and incidence of coronary heart disease

    N Eng J Med

    (2001)
  • C. Cubbin et al.

    Neighborhood context and cardiovascular disease risk factors: the contribution of material deprivation

    Ethn Dis

    (2001)
  • S. Shohaimi et al.

    Residential area deprivation predicts smoking habit independently of individual educational level and occupational social class. A cross sectional study in the Norfolk cohort of the European Investigation into Cancer (EPIC-Norfolk)

    J Epidemiol Community Health

    (2003)
  • S. Shohaimi et al.

    Residential area deprivation predicts fruit and vegetable consumption independently of individual educational level and occupational social class: a cross sectional population study in the Norfolk cohort of the European Prospective Investigation into Cancer (EPIC-Norfolk)

    J Epidemiol Community Health

    (2004)
  • P. Townsend

    Deprivation

    J Soc Pol

    (1987)
  • R. Morris et al.

    Which deprivation? A comparison of selected deprivation indexes

    J Public Health Med

    (1991)
  • Scottish indices of deprivation 2003

    (2003)
  • Measures of deprivation in northern Ireland

    (2001)
  • The English indices of deprivation 2004 (revised)

    (2004)
  • Indices of deprivation 2000

    (2000)
  • D. Trewin

    Socio-economic indexes for areas Australia

    (2003)
  • C. Salmond et al.

    NZDep2001 index of deprivation

    (2002)
  • N. Krieger et al.

    Geocoding and monitoring of US socioeconomic inequalities in mortality and cancer incidence: does the choice of area-based measure and geographic level matter? The Public Health Disparities Geocoding Project

    Am J Epidemiol

    (2002)
  • K. Sundquist et al.

    Care need index, a useful tool for the distribution of primary health care resources

    J Epidemiol Community Health

    (2003)
  • J. Benach et al.

    Geographical patterns of excess mortality in Spain explained by two indices of deprivation

    J Epidemiol Community Health

    (1999)
  • R. Pampalon et al.

    A deprivation index for health and welfare planning in Quebec

    Chronic Dis Can

    (2000)
  • G.K. Singh

    Area deprivation and widening inequalities in US mortality, 1969–1998

    Am J Public Health

    (2003)
  • D. McIntyre et al.

    Geographic patterns of deprivation in South Africa: informing health equity analyses and public resource allocation strategies

    Health Policy Plan

    (2002)
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