Serum Albumin Levels and Economic Status in Japanese Older Adults

PLoS One. 2016 Jun 8;11(6):e0155022. doi: 10.1371/journal.pone.0155022. eCollection 2016.

Abstract

Background: Low serum albumin levels are associated with aging and medical conditions such as cancer, liver dysfunction, inflammation, and malnutrition and might be an independent predictor of long-term mortality in healthy older populations. We tested the hypothesis that economic status is associated with serum albumin levels and explained by nutritional and health status in Japanese older adults.

Design: We performed a cross-sectional analysis using data from the Japan Gerontological Evaluation study (JAGES). The study participants were 6528 functionally independent residents (3189 men and 3339 women) aged ≥65 years living in four municipalities in Aichi prefecture. We used household income as an indicator of economic status. Multiple linear regression was used to compare serum albumin levels in relation to household income, which was classified as low, middle, and high. Additionally, mediation by nutritional and health-related factors was analyzed in multivariable models.

Results: With the middle-income group as reference, participants with low incomes had a significantly lower serum albumin level, even after adjustment for sex, age, residential area, education, marital status, and household structure. The estimated mean difference was -0.17 g/L (95% confidence interval, -0.33 to -0.01 g/L). The relation between serum albumin level and low income became statistically insignificant when "body mass index", "consumption of meat or fish", "self-rated health", "presence of medical conditions", "hyperlipidemia", or "respiratory disease "was included in the model.

Conclusion: Serum albumin levels were lower in Japanese older adults with low economic status. The decrease in albumin levels appears to be mediated by nutrition and health-related factors with low household incomes. Future studies are needed to reveal the existence of other pathways.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Aged, 80 and over
  • Aging / metabolism*
  • Asian People
  • Cross-Sectional Studies
  • Female
  • Humans
  • Income
  • Japan
  • Male
  • Models, Biological*
  • Nutritional Status*
  • Serum Albumin / metabolism*
  • Socioeconomic Factors

Substances

  • Serum Albumin

Grants and funding

This study used data from the Japan Gerontological Evaluation Study (JAGES), a research project conducted by Nihon Fukushi University Center for Well-being and Society. This study was supported by a Strategic Research Foundation Grant-aided Project for Private Universities from the Ministry of Education, Culture, Sport, Science, and Technology, Japan (MEXT), 2009–2013, for the Center for Well-being and Society, Nihon Fukushi University; a Health Labour Sciences Research Grant, Comprehensive Research on Aging and Health (H22-Choju-Shitei-008, H25-Choju-Ippan-003, H25-Kenki-Wakate-015, H26-Choju-Ippan-006) and Comprehensive Research on Lifestyle Disease (H27-Jyunkankito-ippan-002) from the Japanese Ministry of Health, Labour and Welfare; and Grants-in-Aid for Scientific Research (22119506, 22330172, 22390400, 22592327, 23590786, 23700819, 25253052, 23243070, and 26882010) from the Japan Society for the Promotion of Science. NK was also supported by AXA Fixed Income Fund, AXA Life Insurance Co. LTD. He had no role in study design, data collection, analysis and decision to publish. He had helped on preparation of the manuscript. Other funders had no role in study design, decision to publish, or preparation of the manuscript. The authors are particularly grateful to the staff members from each study area and the central office for conducting the survey. The authors would like to thank everyone who participated in the surveys.