**3.4 Structure relationships with "socioeconomic status," "Healthy Diet and Lifestyle," "Three Health-related Dimensions,"and "healthy longevity"**

We adopted and analyzed the statistically best-fitting models by sex using SEM. **Figure 4** shows the models for male and female participants presenting causal relationships among the latent variables. The models fit the data well with the following fit indices: NFI = 0.861, IFI = 0.872, and RMSEA = 0.025. R-squared values also work well: 81 percent for males and 71 percent for females.

The models depict the pathways from "Socioeconomic Status" in 2001 via "Three Health-related Dimensions" in 2001 and "Healthy Diet and Lifestyle" in 2004, leading to both sexes' "Healthy Longevity" from 2004 to 2006.

In addition, the paths from "Three Health-related Dimensions" approached the "Healthy Diet and Lifestyle."We observed a relatively significant direct effect of the "Three Health-related Dimensions" on "Healthy Longevity," with a 0.90 standardized path coefficient (SPC) for males and 0.84 SPC for females. On the other hand, the direct effect of "Healthy diet and Lifestyle" on "Healthy Longevity" was nearly zero (0.00 0.02).

The total effect of "Three Health-related Dimensions" and "Healthy Diet and Lifestyle" supported by "Socioeconomic Status" on "Healthy Longevity" indicated considerably large SPCs for males (0.444) and females (0.580) as a total effect.

#### **3.5 Marital annual income threshold to ensure a certain number of survival days**

We used a one-way analysis of variance to analyze the threshold marital annual income to secure a certain number of survival days. A significant difference was tested

#### **Figure 4.**

*Causal relationship between "socioeconomic status," "Three Health Dimensions," "Healthy Diet and Lifestyle," and "healthy longevity" model for men and female.*

for all combinations of annual income classes by Tamhane's test, which does not assume equal variances [25].

In addition to showing a statistically significant relationship between income and survival days, we clarified that there is a threshold for income to maintain a certain number of survival days.

In the group of 4 million yen or more but less than 5 million yen, there was no significant difference compared to the survival days of the group with more than that. Therefore, 4.5 million yen, the group's median value of 4 million yen to less than 5 million yen, was regarded as the income threshold for maintaining a certain number of survival days (**Table 1**).

The X-axis shown in **Figure 5** is the average income, and the Y-axis indicates the number of days an individual lives. The analysis of older people in suburban cities shows that an income threshold can be seen to ensure a certain number of survival



*Causal Structure for the Healthy Longevity Based on the Socioeconomic Status, Healthy… DOI: http://dx.doi.org/10.5772/intechopen.111910*

#### **Table 1.**

*One-way ANOVA of survival days by marital annual income.*

#### **Figure 5.**

*Annual income threshold for survival days among suburban elderly people for both sexes.*

days. These results suggest that older adults living in the suburbs need a certain amount of income to provide a certain number of survival days.

### **4. Discussion**

### **4.1 Socioeconomic status, dietary and lifestyle habits, three health-related dimensions, and healthy survival days**

Until now, a vast amount of health education has been targeted at elderly populations to foster diet and healthy behavioral change attempts. The underlying evidence supported these aims demonstrating that a healthy diet and lifestyle habits improve individual healthy longevity [6–12].

In contrast, our study revealed that current dietary and lifestyle habits did not determine healthy longevity among the suburban Japanese elderly but by the three health-related dimensions observed three years prior and indirectly by their educational attainment and previous annual income.

This original scientific evidence suggests that it might be of great importance for older people to particularly emphasize the maintenance of mental well-being, physical activity, and social communication/participation based on income rather than urging an improvement of their diet or other health-related behaviors.

It should be noted that this unique scientific evidence suggests the need to maintain mental health, physical activity, and social health for older adults to develop desirable diets and lifestyles. At the same time, they suggested that socioeconomic foundations are essential for the three sensual three health dimension.

It might be incorrect to understand that healthy longevity has become due to advantageous lifestyles. Based on our original causal structure analyses, it should be noted that older people with secured income that allows them to have favorable lifestyle habits may have healthy longevity. In this case, attention should also be paid to the income threshold, which requires a certain amount of income to be secured to maintain certain survival days. These findings should be considered concerning the following three points of argument.

First, most theories calling for a healthy diet and lifestyle changes were derived from previous investigations targeting adults over a wide range of ages [28, 29]. Many studies that identified significant associations between healthy lifestyles and health outcomes incorporated people in early, middle, and later adulthood [30, 31].

As a result, much evidence-based health education has also been assumed to be fully applicable to older people. Thus, we should distinguish between healthy aging led by healthy life habits during younger life periods influenced by their parents.

Second, several reports have addressed a significant association between healthy habits and health outcomes among elderly populations [32–35]. These studies focused on the relationship between healthy habits and health outcomes adjusted only for individual essential demographic variables without any attention to the confounding factors.

In comparison, our study analyzed associations between healthy habits and outcomes embedded in a model with a broader spectrum involving socioeconomic and health-related dimensional compartments resulting in control over as many potential confounds as possible for the first time until now [25, 26, 36].

Reproducibility by covariance structure analysis is expected by utilizing the results of three surveys of the same person every three years and data that clarify the survival and degree of care required after three years.

#### *Causal Structure for the Healthy Longevity Based on the Socioeconomic Status, Healthy… DOI: http://dx.doi.org/10.5772/intechopen.111910*

Our findings suggest, therefore, that the described associations between healthy habits and elderly healthy survival (showed **Figure 3**) might be confounded with socioeconomic status and health-related dimensional factors.

Third, although chronological analysis can reveal causal relationships among different latent variables, up until now, there have been few studies using this analysis in the gerontology research area. The current studies were the first trial to investigate causal associations by the SEM method using longitudinal data following the same subjects across six years, including survival days [25, 26, 36].

According to the standardized effects, we have been shown that dietary health and lifestyle habits did not cause healthy longevity. Longevity without bedridden status was the effect of physical, mental, and social health supported by socioeconomic status rather than a healthy diet and lifestyle (**Figure 4**).

Our study verified a solid causal association from three years earlier of three health-related dimensions toward the degree of nursing care and survival rate. Other studies have presented the expected consequence that mortality among older people is significantly associated with their physical health [19, 28], mental health [22, 35], and social health [28].

The current study incorporated the three health states into one latent variable using data from the same year (the three health-rated dimensions), as our previous reports suggest [26]. However, the reciprocal correlation among variables of the three health states does not coincidentally occur. Still, rather social health may be affected by mental health directly and by physical health indirectly in different chronological periods [36, 37].

**Figure 4** shows the nearly null effect of healthy diet and lifestyle habits on healthy longevity. This finding opposed previous studies [6–12], as discussed above. However, these results are supported by the study of Diehr et al. [32] in those older adults aged 65 years and over who were overweight or obese had no worse and sometimes better outcomes in categories such as the activity of daily living, years of healthy life and active life expectancy compared to individuals of average weight.

From our perspective, it is assumed that overweight or obese conditions resulting from dietary health and lifestyle habits may have little influence on elderly health and living conditions.

Using covariance structure analysis, we analyzed the relationship between educational attainment, annual marital income, and health, namely physical, mental, and social health. As a result, it is clarified that educational attainment about half a century ago determined the annual income of married couples and that socioeconomic factors have a more decisive influence on both mental health and social health, subsequently support physical health, and ultimately affect social health.

The standardized estimate, which indicates the direct effect of socioeconomic factors on physical health, was tiny at 0.04. Forty-three percentage of social health could be explained. Analyses by gender showed almost similar results (**Figure 5**).

This new evidence would be completely new knowledge from an international perspective, and reproducibility is required.

Our research shows that the effects of educational attainment and income on healthy longevity are not direct but may have indirect effects through the three health factors (**Figure 4**). Several studies support our work. Based on the multivariate analysis, an extensive census data analysis of Estonia showed that educational differences in mortality were observed between men and women. Specifically, we showed that people with a more extended education period than those with the lowest education level were more likely to live 13.1 years longer for men and 8.6 years longer for women [38].

Manox et al. clarified through covariance variance structure analysis that educational attainment does not directly affect health but leads to health maintenance as a more indirect and distal end effect of entering a desirable occupation and maintaining income [39].

Similarly, Wardle et al. [40] reported that indexed status by occupational social class was significantly associated with favorable attitudes underlying various health behaviors and their health-sustaining effects, regardless of age or gender.

Our study shows that socioeconomic status may increase awareness, and the three desirable health factors may favor eating and lifestyle habits. In other words, favorable eating habits and lifestyle habits may not ultimately determine healthy longevity.

Instead, it was shown that economically sound groups that can maintain good eating habits and lifestyles based on desirable socioeconomic factors, especially those with sensual mental health, may be linked to healthy longevity, which is the final effect. Thus, as Manox et al. [39] pointed out, the achievement of higher education supported that it could have a distal impact on health outcomes through the expansion of social status, the type of occupation, and the potential for increased income.

This study had some limitations. In September 2001, the initial response rate was as high as 80.2%, but in the second round in September 2004, it fell to 52.0%. In particular, older people may have been missing more due to increased institutional admissions and deaths in hospitals and long-term care homes. This increase in the exclusion ratio of the target population could lead to random error and selection bias. Therefore, since excluding data with missing values would improve the fit of the model using SEM, the final analysis excluded data with one or more missing observed variables.

However, the exclusion of missing data did not change the study results. Therefore, the selection bias was insignificant even in this study, which shows missing values. It is unclear which of the three health factors indicated by the WHO has a more substantial impact on healthy longevity. As shown in **Figure 6**, socioeconomic factors can primarily strongly affect mental health and social health. However, it is entirely unclear which physical, mental, and social health factors contribute the most to healthy life expectancy. These hypotheses are our following research topics. More detailed follow-up is needed.

A review of our research yielded the following conclusions: It was revealed that healthy older people in the physical, mental, and social spheres were more likely to practice healthy eating habits and lifestyle habits. On the other hand, it was shown that a healthy diet and lifestyle might not directly affect healthy longevity, which is not required for long-term care but has a long survival day. Instead, healthy longevity could be directly affected by the three favorable health factors indicated by the WHO, which are socioeconomically supported. However, to make promising eating habits and lifestyle habits, it is necessary to maintain the three health factors supported by socioeconomic factors. Therefore, it is required to pay attention to the three health factors supported by economic independence and a healthy lifestyle strongly influenced by the three health factors.

It should be noted that socioeconomic factors are the essential foundation for the elderly to maintain healthy longevity, even if the continuation of undesirable lifestyle habits hinders healthy longevity.

As a result, attention should not be paid to the individual's only responsibility. Much more attention should be paid to public commitment to creating a supportive environment.

*Causal Structure for the Healthy Longevity Based on the Socioeconomic Status, Healthy… DOI: http://dx.doi.org/10.5772/intechopen.111910*

**Figure 6.**

*Social health is a causal structure based on socioeconomic factors to support mental health and is determined through subsequent physical health for both sexes.*

#### **4.2 Marital annual income threshold to maintain survival**

One of the leading scientific findings revealed by this study is that the marital yearly income threshold required to keep the number of survival days has been clarified.

In addition to showing a statistically significant relationship between income and survival days, we clarified that there is a threshold for income to maintain a certain number of survival days. For the elderly, it wa s4.5 million yen(0.0346 million US \$) for both sexes as a marital yearly income.

In future research, it will be necessary to conduct an analysis based on equivalent income that considers family members, as some people live alone without a spouse. In addition, this survey did not implement survey items such as living conditions. These are a topic for future research.

Other than our previous study [25], no further research has been reported in Japan that has tracked survival concerning the amount of annual income that determines the number of survival days of individual life. Therefore, to improve the validity, additional tests are required, and reproducibility is required.

According to the 2021 Wage Structure Basic Statistical Survey [27, 41], Japan's Ministry of Health, Labor and Welfare reported the average monthly income for fulltime workers in 2021 was 0.037 million Japanese yen. Twenty years ago, in 2001, the average monthly salary was 0.036 million yen. In this way, changes in the amount of personal income in Japan over time have remained almost constant over the past 20 years, making it one of the countries with a minor increase in revenue among the advanced G7 countries.

Although the increase in average life expectancy in Japan slowed down, it continued to increase to the same level as in developed countries where personal income is rising. This suggests that income alone cannot explain the factors determining extending life expectancy. This fact can also reveal that Okinawa Prefecture, which

has the lowest income in Japan, had the longest average life expectancy and that Tokyo, which has the highest income city, does not have the longest average life expectancy.

The authors [42] have clarified that the average life expectancy of municipalities with a large population in Japan increases significantly with the elevation of latitude in the municipality location. This fact suggests that even if medical care in high-altitude provincial cities is not better than in urban areas, unpolluted water sources are secured, and the natural environment surrounded by abundant greenery contributes to the extension of the lifespan of living organisms.

Therefore, it is presumed that the community's natural environment and social networks are favorable factors for extending the average life expectancy, assuming that a constant income is secured and relative poverty is low.

It has been reported that other factors that determine the survival day and heredity are reflected in survival in old age about half a century later. For example, it explains the causal relationship that growth is retarded and short stature increases the mortality rate in the period when the height increases [43]. Regarding the mechanism, Davey et al. [44] reported that the socioeconomic factors of the parents in childhood reflected the nutritional status of the family, and the child's significant organs reached a level where they could fully demonstrate their functions.

Hasegawa et al. [45] reported the causal relationship between socioeconomic factors and lifestyle habits on the survival rate of urban older adults, following the survival of 8,285 people for three years. Socioeconomic factors indirectly affect healthy life maintenance via the three health factors and report the possibility that socioeconomic status is the basis of survival.

The results of this research followed previous research [12, 17, 40] that it is necessary to secure a certain level of income to maintain survival days. In the future, it will be required to verify the effects of social security policy interventions to correct health disparities.

Our studies suggest that there may be a threshold for the number of years alive and related annual income. However, the research method had limitations. In addition, many issues can be pointed out to improve the research results' validity.

As for the annual income question, objective information such as equivalent income and whole-life income should be added to consider equivalent disposable income. In addition, The next research topic is to add survey items such as subjective questions such as economic living conditions and satisfaction with health [46], which are reported to be related to survival.

A future research subject is to increase the results' internal and external validity by random sampling.
