To the best of our knowledge, this is the largest survey on social frailty among older adults in urban and rural China performed to date. This study revealed the prevalence of social frailty among older adults in China and identified health risk factors and socioeconomic factors associated with the occurrence of social frailty.
Social frailty is defined as the absence of social resources, limited social activity and the inability to accomplish basic social needs. In 2017, Bunt et al. conducted a systematic search of the literature related to social frailty in older adults and, after analyzing factors influencing social frailty in previous reports and based on the concept of social needs in Social Production Functions Theory (SPFT), defined social frailty for the first time as occurring when an individual constantly lacks one or more important resources necessary to meet basic social needs. Furthermore, their findings suggest that the components of social frailty include not only a lack of social resources to meet basic social needs, but also a lack of social behavior and social activities, as well as a lack of self-management skills15.
The concept of social frailty has received significant attention since its introduction. However, there is little consensus regarding the criteria for its definition. No agreement has been reached in terms of which indicators of social frailty should be evaluated, which methods of assessing social frailty are most effective or which interventional approaches should be used to address social frailty. Social components of frailty vary from instrument to instrument and address the concepts of social isolation, loneliness, social networks, social support and social participation.17 Several instruments have previously been used to assess social frailty among community-dwelling older adults, with various frailty instruments most commonly evaluating social activities, social support, social networks, loneliness and living alone.12, 16, 17, 19, 21, 24, 33–36Therefore, our social frailty index was operationalized based on several previous studies6, 12–16, 20–21, 30–36 and to be compatible with China's national conditions, incorporating the five most aspects most commonly used to assess social frailty (namely, inability to help others, limited social participation, loneliness, financial difficultly, and living alone) to create the “HALFE” scale. Similar to previous studies, we employed participants' living status (living alone or with someone) as a screening indicator for social frailty.22, 23, 30–32, 37–38 In China, with fewer children, population aging and shrinking families, the number of elderly people living alone is increasing. In 2010, there were 18,243,900 elderly people aged 60 and above living alone in China, and the number of elderly people aged 65 and above living alone in China increased by 6,604,600 households from 2000 to 2010 (an average annual increase of 660,500 households), an increase of 84.3% and an average annual growth rate of 6.3%.39 Therefore, the country needs to prepare for social frailty caused by population aging and a rapid increase in the number of older adults living alone. Meta-analysis shows a significant association between living alone and frailty. Older adults living alone are at risk of social isolation, loneliness, and depression due to poor social networks.40
This cross-sectional study included a larger sample than previous studies in China. Previous small studies have reported that the prevalence of social frailty in the Chinese population is 7.7%.20 This study determined that the prevalence of social frailty in the Chinese population is 15.2%, significantly lower than reported in Korea (44.7%) 30 and falling between Singapore (18.4%) and Japan (11.1%).21, 24 Additionally, our study sample was composed of community-dwelling older adults living in both rural and urban areas, without any exclusion criteria related to disabilities in activities of daily living or severe diseases 21 or long-term care recipients 23. Therefore, the major differences between this study previous studies concern the items included on the social frailty questionnaire and the study population.
This study showed that the prevalence of social frailty varies by age. The prevalence of social frailty gradually increases with aging in those aged 80 or less, then decreases with aging in those over 80. The highest prevalence of social frailty was observed for participants 75–79 years old, which is different from previous studies.16 Life expectancy per capita in China was 77 years in 2018.41 It remains unclear whether it is coincidental that the age group of 75–79 years features both the highest prevalence of social frailty and average life expectancy. Social frailty is associated with lower dietary intake, poor diet quality, and poor nutrition among community-dwelling older men, and it predicts physical frailty, cognitive decline, hospitalization and mortality in community-dwelling older adults. 19–25 The prevalence of social frailty decreases for those aged 80 and over, possibly because it is more common for older adults without social frailty to survive to older ages. It may also be related to the fact that older adults require more companions, are less likely to live alone, and have more social interactions, thus reducing the prevalence of social frailty.
The age-specific prevalence of social frailty differs from that of physical frailty, which increases progressively with age. The incidence of physical frailty is higher in women than in men during advanced age 42–44, while social frailty in this study was highest for the ages of 75–79 years, but did not differ significantly by gender. In addition, physical frailty is more common among those with low educational levels, whereas social frailty was not significantly related to educational level in this study according to multivariate analysis; rather, other factors, such as urban-rural differences, had a greater impact on social frailty.
In this study, we found a significant relationship between social frailty and spousal presence, with a significantly lower incidence of social frailty among those with spouses and singlehood identified as a risk factor for social frailty. Older singles must perform their own chores independently and have limited communication with others and limited social connections. These limitations may have negative effects on older adults, including reduced physical, cognitive and social stimulation. Single older adults mostly live alone, with reduced social participation and increased risk of functional deterioration.16 Previous studies have found that being married is significantly associated with reduced frailty in older adults 45–48 because of the increased social support and reduced incidence of risk behaviors among married individuals 49, and older adults with spouses tend to have better physical status. Due to the narrowing of social networks in later years of life, marriage is a central resource for social support, 50 especially when social engagement is limited. Marriage may promote health through various causal mechanisms, including gaining legal access to marital assets and resources, monitoring spouses’ health status and behaviors, and forming social bonds.45 Married individuals have greater access to social, psychological and economic resources than singles, all of which promote health and longevity.
We found that housing satisfaction is significantly associated with social frailty. A small number of previous studies have found a correlation between housing/relocation and social frailty.51 China is a vast country with uneven social development and disparate social conditions in urban and rural areas. There are also significant differences in housing, including those who own their own housing, rent apartments, or live with their children. Chinese elderly people mainly live at home, and factors such as private housing and the presence of an elevator, alarm facilities, and sufficient light may pose inconvenience and safety concerns to the elderly. We found a significant correlation between housing dissatisfaction and social frailty. Housing satisfaction, favorable living environments and appropriate housing facilities to promote active living can help the elderly with social activities and interactions. In addition, elderly respondents who reported being satisfied with their housing are generally better off financially, which is one factor associated with reduced social frailty. Although the government has already started to improve the housing of elderly people, the relationship between housing status and social frailty requires further research.
Our survey shows a large difference between urban and rural social frailty in mainland China, with a significantly higher prevalence in rural populations than urban. This difference is related to the overall higher economic and cultural level and living conditions associated with urban environments. Therefore, economic development and elimination of the urban-rural gap is critical to reduce social frailty.
The advantages of this study include its large sample size and the use of a tractable method to identify social frailty. However, large sample sizes can lead to statistical differences with little association between groups, with special attention required for the interpretation of statistical results in this paper. Our study may serve as a basis for future research evaluating the value of social and economic factors in the design of targeted interventions for frailty. Prospective studies are needed to identify the causal relationships between socioeconomic factors and frailty, and further research is required to identify the specific mechanisms underlying the association between socioeconomic factors and frailty among older people.
However, this study also has some limitations. First, due to the use of cross-sectional data, causality could not be explored; this should be clarified in a future prospective study. Second, the categories of social frailty were based on recent studies, rather than on an established method. Therefore, future research on the development of tools to measure social frailty is needed. Third, this study identified many factors associated with social frailty, and we have only discussed some of them. Further analysis of other relevant factors is needed in the future. It is important that future studies determine which social components of frailty contribute most strongly to increased vulnerability and greater risk of adverse outcomes. Further studies are also needed to develop efficient intervention strategies for social frailty to improve and enhance life satisfaction.