One of the major characteristics of global standard datasets, including the Japanese Study of Aging and Retirement (JSTAR), is their interdisciplinary approach whereby joint research is undertaken with the involvement of not only economists but also sociologists, psychologists, and above all, medical scientists and epidemiologists.
In particular, the relationship between health factors and socioeconomic factors (income, educational attainment) is one of the topics receiving growing attention globally. Our cross-sectional analysis of the JSTAR data has found that a very large number of health indicators are significantly correlated with socioeconomic factors. Specifically, these indicators include self-rated health status, activities of daily living (ADLs), prevalence (hyperlipidemia, diabetes, cerebral embolism, chronic lung disease, arthritis, etc.), sensory function, mental health (depression), cognitive function, consultation behavior (outpatient service, inpatient service, dental service), health behavior (smoking, health checkups), nutrition intake (sodium, fat, cholesterol, fruits and vegetables), and others.
Another interesting finding is that income and education have different impacts on health. While educational attainment rarely changes after reaching middle age, income tends to change with age. In our joint research with Professor Hideki Hashimoto of the University of Tokyo, we found a significant correlation between nutritional intake and educational attainment, but not between nutritional intake and income.
In Japan, we have a universal health care insurance system that guarantees universal access to medical services. Nevertheless, there exist significant differences in the health status of the middle and elderly people, and such differences are significantly correlated with socioeconomic factors. These facts indicate that it is necessary to look at individual diversity in various dimensions and that people's health is influenced not only by medical policy but also by socioeconomic policy. For example, while those with higher educational attainment and higher income show a greater tendency to have health checkups, they have relatively low health risks. In other words, those with relatively low health risks tend to get health checkups proactively. At the same time, from a policy viewpoint that defines health checkups as one of the precautionary measures to curb medical expenditures, this points to the critical importance of implementing measures to encourage those with high health risks to have health checkups.
Policy responses would differ depending on how we define causal relationships. However, it is difficult to identify causal relationships between health and socioeconomic factors as they interact and mutually influence each other. This is why the use of panel data is essential. For instance, if data collected in the course of a panel survey have enabled us to conclude that income decline resulting from an external shock has caused many people to suffer depression, we can see that greater redistribution of income would prevent the problem to some extent. A panel survey can also help us answer the fundamental question of the disparity argument: "Are disparities locked in?" It is hoped that we will be able to explain such fundamental issues sequentially as we proceed through more rounds of the JSTAR survey.
* Translated by RIETI from the original Japanese "Yasashii Keizaigaku" column in the September 19, 2011 issue of Nihon Keizai Shimbun.
