Factors affecting the survival probability of becoming a centenarian for those aged 70, based on the human mortality database: income, health expenditure, telephone, and sanitation

What are the factors that affect the survival probability of becoming a centenarian for those aged 70? Do the factors include income, health expenditure, the use of mobile telephones, or sanitation?

In many countries, the survival probability of becoming a centenarian (SPBC) has been increasing over the past several decades, particularly among women. While the survival of centenarians is improving, at least in some countries, it is not possible to determine whether the natural life span has increased overall [1]. However, the SPBC may have been affected by the above socioeconomic indicators. This retrospective analysis of the socioeconomic factors, which contribute to the SPBC, may help identify the factors associated with healthy aging.

Today, the population of centenarians is steadily increasing globally [2]. Over the past half-century, the number of centenarians has dramatically increased [3]. The determinants regarding the increase in the number of centenarians include the cohort size at selected ages, along with the probability of survival at selected ages [4]. Namely, the number of centenarians reflects an estimate of the production of centenarians at selected ages, which is the survival probability of becoming a centenarian within a population. Therefore, the SPBC is defined as an estimate of the production of centenarians by a population. Further, the SPBC (70) is the survival probability of becoming a centenarian for those who are aged 70.

Historically, Sachuk [5] first suggested the longevity index in 1970, as the proportion between the number of centenarians and the total population [6]. This value depends on the population structure [7]. The SPBC (70), as an indicator of healthy aging, is based on an unchanged age-specific fertility, as well as on the absence of migration in populations. However, in this study, the SPBC (70), as the centenarian rate has nothing to do with fertility, because the study cohorts have already reached the age of 70. Meanwhile, the probability of survival as the number of centenarians, suggested by Robine and Caselli [4], used to be an indicator of healthy aging in response to the imperfection of the longevity index, thereby resulting in a longevity index that is used in certain countries [4‐6, 8, 9].

Healthy aging is an important aspect for the health of centenarians. It requires older people to have access to appropriate improved sanitation facilities; moreover, public expenditure on health and a sense of satisfaction with their level of income, as well as using mobile phones as the standard of living, are essential as well. This paper therefore seeks to determine the association between such socioeconomic indicators, and the SPBC (70).

In particular, although knowledge of the determinants of healthy aging is limited, healthy aging of centenarians is a multifactorial quantitative trait that is influenced by biological, environmental, and psychosocial factors [10]. Among all these elements, socioeconomic factors, as modifiable risk factors, have been researched in several studies. In brief, studies have shown that environmental health factors, such as drinking water and sanitation facilities, can predict mortality in incidences of cancer and diarrhea [11, 12]. However, it is uncertain as to whether these associations are applicable to the SPBC (70), as the production of centenarians. The results concerning the association between the use of telephones, the use of mobile phones, and the improvement of health outcomes, have also been studied [13, 14]. However, it is uncertain as to whether these associations are applicable to the SPBC (70) as the number of centenarians. Finally, previous reports have supported the hypothesis that the associations between national economic indicators and relative fitness among the older population are positive [15]; however, these relations have not been confirmed in other studies of centenarians [16]. Although the socioeconomic indicators, as modifiable risk factors, have been studied in several studies, it is uncertain as to whether these associations are applicable to the production of centenarians.

Therefore, this study has examined the associations of independent socioeconomic indicators with SPBC (70), as the number of centenarians. Further, this study estimates the influence that correlates between the SPBC (70) and gross national income, health expenditure, the use of mobile telephones, and sanitation facilities, as the socioeconomic indicators in 32 countries. Overall, this study aims to estimate the association between the SPBC (70) and socioeconomic factors, by using Pearson’s correlation coefficients and multiple regression models.

This study investigated the socioeconomic factors associated with the SPBC (70). The present SPBC (70) MF, which is based on a study of centenarians and factors from the national censuses of 32 countries examined in this study, indicated an average of 80.28 centenarians per 10,000. In this study, the SPBC (70) was used to help create a model identifying the socioeconomic factors on the survival probability of becoming a centenarian for those aged 70.

First, the social factor of ISF (2005–2010), which indirectly reflects the environmental health [11, 12, 22‐24] that is necessary for the survival probability of becoming centenarians, was included in all Models 1, 2 and 3 of females and males, which were found to be a significant factor for the production of centenarians. In the current study, the ISF in Russia (ISF=75%) was the lowest among all 32 countries; whereas, those of Japan, Canada, Switzerland and United Kingdom (ISF=100%) were the highest. The ISF is likely to be a major contributing factor to a high SPBC (70) in certain countries. The mortality rate stemming from the ISF is also a well-known public health concern. This implies that older people who are vulnerable to the risk of ISF might not have the same life expectancy as centenarians. In Russia, the occurrence of typhus epidemic, particularly in circumstances where people are interned under poor hygienic conditions, should be regarded as a barometer for the general social situation. If these indicators are ignored, the consequences could be disastrous [29]. These examples should highlight the fact that immediate intervention to combat the louse epidemic is essential, in order to eradicate emerging typhus among the general population of Russia [29]. This notion means ensuring that the importance of sanitation for infectious diseases is recognised. On the other hand, Russia has the lowest ISF for the production of centenarians, because both of these variables are reflective of a lack of any government investment in health and hygiene facilities infrastructure. The production of centenarians in this study has been indirectly affected by the environment health factors, namely the ISF. Therefore, among the centenarians, the higher the ISF, the greater is the promotion of health as a preventive measure against infectious diseases [22, 23] and sanitary facilities [24]. Simultaneously, using the ISF might help maintain the requisite environmental health for the production of centenarians. Therefore, the predictors’ correlations between the SPBC (70) and ISF are strongly positive, which may well indicate that the ISF is an important independent contributor to the survival probability of becoming centenarians.

Second, the social factor of FMTS (1980–2000), which indirectly reflects the standard of living, can contribute to the health aspect, by accessing health-related information [13, 14], as well as the high-levels in the quality of life [9]; these were included in all Models 1, 2, and 3 of females and males. Increases in FMTS led to an increase in SPBC (70) values, suggesting that they are significant contributory factors to the healthy aging and production of centenarians. In the current study, the FMTS score in Poland (FMTS=7) was the lowest among all 32 countries; whereas, that of Sweden (ISF=66) was the highest. The FMTS is likely to be a major contributing factor to a higher SPBC (70) in 32 countries. Therefore, the FMTS was included in all Models 1, 2 and 3 of females and males, which indirectly reflect the health factors for both social well-being and standard of living, which are necessary for healthy aging and the production of centenarians; further, they were found to be significant factors of healthy aging (Tables 4 and 5). This result implies that the current study has high correlations between FMTS and the survival probability of becoming centenarians, because both of these variables are reflective of the government’s investment in telecommunications infrastructure in health, high-level in the quality of life, and individual income of citizens in developed countries [9]. On the other hand, if an individual’s mental health improves by periodic telephone counseling, then human relationships, which maintain social relationships with family and friends in the oldest-old, might have beneficial effects on mental health [30, 31]. Therefore, periodic telephone counseling appears to have an important latent effect on mortality into late life [31]. Moreover, telemedicine and conventional health services are complementary for enhancing the health status in an aging society [32]. The FMTS is an important independent contributor to the survival probability of becoming centenarians for those aged 70 (Tables 4 and 5).

Finally, economic factors of PEHGDP (2000–2010) and GNI (1990–2010), which indirectly reflect the standard of living and income level [9, 15] that are necessary for the survival probability of becoming centenarians, were included in all Models 1, 2 and 3 of females and males; moreover, they were found to be a significant factor in the production of centenarians. In the current study, the PEHGDP in Russia (PEHGDP=3.2) and GNI in the Ukraine (GNI= 7095) were the lowest among all 32 countries; whereas, the PEHGDP in France (PEHGDP=8.65) and GNI in Luxembourg (GNI=44679) were the highest. The PEHGDP and GNI are likely to be major contributing factors to a high SPBC (70) in certain countries. Increases in the GNI and PEHGDP led to an increase in the SPBC (70), thereby suggesting that the PEHGDP and GNI are significant factors of the production of centenarians in all models of females and males. Although the relationship of economic indicators with health is unclear, lower income has been associated with morbidity [15]. In fact, death rates exceeded emergency thresholds at 4 sites during epidemics of Plasmodium falciparum malaria in Burundi [33]. However, in higher-income countries, the prevalence of frailty is lower, and people live longer [15]. Therefore, Models 1, 2, and 3 of females and males predictors’ correlations between the SPBC (70) and the PEHGDP and GNI are all strongly positive, which may well indicate that the PEHGDP and GNI are important independent contributors to the production of centenarians, and the survival probability of becoming centenarians.

In the meantime, we have examined whether these factors have the same impact on both females and males [34]. The SPBC (70) of females and males, an indicator for assessing the production of centenarians, reflects the overall economic development level, mobile telephone subscribers, health expenditure, and sanitation facilities level in 32 countries. However, females have more to do with the power of explanation of these factors, than do males (Table 5; Males, R²= 0.303; Females, R²= 0.439)).

Meanwhile, although the data quality of HMD is better compared to the UN data, the HMD data are not free from biases. For example, age exaggeration at very old ages in the U.S.A., as well as in some other countries, is not uncommon [35]. One of the simplest ways to check this is to compare the percentage distribution from age 95 to age 105 (see Additional file 2, Additional file 3). If a distribution is not in line with those of Sweden or Japan, the data quality of centenarians is likely poor [36]. The results of the data quality assessment of centenarians might have possible biases of such data.

The limitations regarding the accuracy of development variables are insufficient information for some countries over the past thirty years from 1980 to 2010. However, this study has used the mean rate of change index (MRCI), by considering the time and outcome, such as considering the growth rate, or rate of decline, in order to measure the change of socioeconomic indicators during the past thirty years.

Hence, the hypothesis states that the associations between SPBC (70) and socioeconomic factors (GNI, PEHGDP FMTS, ISF) could predict the healthy aging and production of centenarians. Hence, these factors could be explained by the survival probability of becoming centenarians that affects the healthy living of centenarians. For the proposed Models 1, 2, and 3 of females and males, if countries were to have higher GNI and PEHGDP, and higher FMTS and ISF factors, these factors would surely have an impact on the increase of SPBC (70) in all 32 countries.

The socioeconomic level in all 32 countries appears to have an important latent effect on the production of centenarians in both females and males. This study has identified the following four important aspects of socioeconomic indicators in the survival probability of becoming a centenarian for those aged 70: higher overall economic development level, public expenditure on health of GDP, mobile telephone subscribers as the standard of living, and the use of improved sanitation facilities for healthy aging. Thus, the socioeconomic level seems to affect an important on the survival probability of becoming a centenarian.