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Epidemiology
Research
Social and geographic inequalities in premature adult mortality in Japan: a multilevel observational study from 1970 to 2005
  1. Etsuji Suzuki1,
  2. Saori Kashima1,2,
  3. Ichiro Kawachi3,
  4. S V Subramanian3
  1. 1Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
  2. 2Department of Public Health and Health Policy, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan
  3. 3Department of Society, Human Development, and Health, Harvard School of Public Health, Boston, Massachusetts, USA
  1. Correspondence to Dr Etsuji Suzuki; etsuji-s{at}cc.okayama-u.ac.jp Dr S V Subramanian; svsubram{at}hsph.harvard.edu

Abstract

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.

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: http://creativecommons.org/licenses/by-nc/2.0/ and http://creativecommons.org/licenses/by-nc/2.0/legalcode.

https://doi.org/10.1136/bmjopen-2011-000425

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    Footnotes

    • To cite: Suzuki E, Kashima S, Kawachi I, et al. Social and geographic inequalities in premature adult mortality in Japan: a multilevel observational study from 1970 to 2005. BMJ Open 2012;2:e000425. doi:10.1136/bmjopen-2011-000425

    • Contributors SVS and ES conceived the idea and design of the study. ES led the data collection, data analysis, interpretation of the findings and writing of the manuscript. SVS supervised the study and contributed to the interpretation of findings and writing of the manuscript. SK contributed to the data analysis, literature review and writing of the manuscript. IK contributed to the interpretation of the findings and writing of the manuscript. All authors have read and approved the final version of the manuscript.

    • Funding A part of this research was supported by a Grant-in-Aid for Scientific Research, Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. The funding source had no role in study design, data collection, data analysis, data interpretation, the writing of the report or the decision to submit for publication.

    • Competing interests All authors have completed the ICMJE uniform disclosure form at http://www.icmje.org/coi_disclosure.pdf (available on request from the corresponding authors) and declare that SVS is supported by a Robert Wood Johnson Investigator Award in Health Policy Research and by a career development award from the National Institutes of Health (NHLBI K25 HL081275); no financial relationships with any organisations that might have an interest in the submitted work in the previous 3 years; no other relationships or activities that could appear to have influenced the submitted work.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement No additional data available.