Trends in Health Inequalities by Household Income in Japan in the 2010s

Estimates from the National Health and Nutrition Survey Reports

Abstract

Objectives: The purpose of this study was to estimate the trends in health inequalities by household income in Japan in the 2010s, based on the data shown in the National Health and Nutrition Survey reports.

Methods: Among the food intakes, body shape, and lifestyle habits by annual household income shown in the reports of the National Health and Nutrition Surveys in 2010, 2011, 2014, and 2018, the vegetable intake (g), fruit intake (g), seafood intake (g), meat intake (g), obesity rate (%), rate of without exercise habits (%), and smoking rate (%) were comparable estimates (according to gender; adjusted for age and number of household members). Therefore, I used these items for the analyses. Note that, the estimates of body shape and lifestyle habits for 2011, and food intake for 2010 were not shown, therefore I could not use. First, we calculated the difference between the <2 million yen and ≥6 million yen household income groups for each year. Next, we calculated the difference by survey year of the previously calculated difference by household income (two ways: 2014 - 2010 or 2011, and 2018 - 2010 or 2011). In addition, 95% confidence intervals were calculated from the standard errors of the estimates

Results: The 95% confidence intervals for the difference between the <2 million yen and ≥6 million yen household income groups in each year did not over zero for many items for both men and women. The 95% confidence intervals for the difference in annual household income by survey year were over zero for most items for both men and women.

Conclusion: Health inequalities by household income in the 2010s in Japan for the items evaluated in this study remained mostly unchanged.