In this present study, our results showed that physical frailty was highly prevalent among older adults living in nursing homes in China, especially in women. We observed older age, being women, living in a private institution, living alone or others unknown person, having no regular exercise, and poor self-reported health was significantly associated with physical frailty. Also, we found that although physical frailty, to some extent, overlapped with disability and comorbidity, many frail participants did not have disability or comorbidity, suggesting that physical frailty did not equate with comorbidity or disability in the population of elderly nursing home residents. At present, there is no the gold standard for comprehensive geriatric assessment which is the standard for admission in the resident assessment instrument among the elderly living in nursing homes in China, therefore, China does not use RAI as that is what is in use in North America and Europe in most nursing homes as the standard and that data can be automatically converted in the frailty index [23].
Our preliminary study underlined the fact that as high as about one-half of the older adults living in nursing homes were frail, and 38.5% were still prefrail; moreover, women were frailer than men. Many studies [24–26] from different countries (i.e., Japan, South Italy) are consistent with our results, which demonstrated that frailty was highly prevalent, and the prevalence of frailty in women was higher than in men. A greater understanding of the reasons and implications of this physical phenotype across sex is required. An important reason suggested is that older women with frailty have more abdominal fat than older men[27]. The abdominal adiposity was associated with systemic inflammation by mediating its link with metabolic syndromes, which was higher markers of oxidative stress resulting in skeletal muscle damage and low grip strength [27]. This factor might be a core mechanism leading to sex-associated frailty. However, in nursing homes in China, women were also older, and women more often than men had better learned to take care of themselves and others and to arrange care. Hence, it would be interesting to look at who is admitted and why to live in a nursing home, men may be admitted with lower frailty levels when they live alone because they are less able to support themselves or organize support for themselves [28]. Therefore, we can make effective interventions to prevent or delay the onset of frailty according to the result of the sex differences in frail older adults.
In agreement with some previous studies in other countries [8, 19, 29], we also observed that the prevalence of frailty increased with older age. In term of the associations between physical frailty and style of the institution, the present study was the first, to our knowledge, that had observed such an association. The possible explanation could be that older people who had been living in a private institution (more expensive in the metropolitan areas than public institution) usually have higher social economic status; they were more likely to feel lonely [30] and loss of appetite [31] when staying away from family and changing their ways of previous life, resulting in higher likelihood of being frailer. Compared with people living with their partners in the same nursing home, those who live with alone or share the room with unknown person may become more frail because of poorer social ties [32] and mental disorders [33]. In line with previous studies [34, 35], we also found that regular exercise was associated with physical frailty. One explanation is that there is a vicious cycle: due to the fear of falling [36], as the level of frailty increases, so does the tendency to avoid taking regular exercise. Participants with frailty had poorer self-reported health in our study, in concordance with results from previous studies[12, 37, 38]. This might be explained that frail older people have a state of greater vulnerability [39], so they were more likely to rate their health poorly. In all, the potential role of those factors of physical frailty warrant further investigations to explore their clinical application among elderly nursing home residents.
Reduced physical function reserve (i.e., physical frailty) may occur without showing any difficulties in tasks of daily living or having multiple chronic diseases [4]. However, there are concerns that whether physical frailty is synonymous to disability or comorbidity among the elderly in nursing homes in China. This is because most older adults who moved to nursing homes are usually severely physically dependent and suffering from comorbidities [40–42] as most older people tend to living at home with their families in keeping with the traditional family value in China [43, 44]. In the present study, in contrast, we found that many frail participants did not have disability or comorbidity, indicating that physical frailty did not equate with comorbidity or disability in the population of elderly nursing home residents. Our findings suggest that, physical frailty, related but distinct from disability and comorbidity, can be integrated into nursing-home settings as part of risk stratification and may serve a useful target for preventive interventions.
Our study had several strengths. Firstly, weakness and slowness for defining physical frailty were recorded by objective measures. Secondly, this study comprehensively reporting examined substantial sociodemographic differences in physical frailty prevalence. However, there were limitations to our study. Firstly, the limitations of the present study could lie in the cross-sectional study, there was no follow up to observe the progression from pre-frailty to frailty, and to establish causality of frailty and adverse health outcomes. Therefore, further research will be verified by the temporality of the exposure-effect association. Besides, because of the relatively low response rate, selection bias might have existed in our study. We could speculate that older people in nursing homes not participating might be frailer. Moreover, because most older adults in nursing homes were more 80 years and over, we might have underestimated frailty status.