To the best of our knowledge, this paper is the first review, through descriptive analysis and meta-analysis, to systematically evaluate the influencing factors affecting frailty in CHF patients. As seen from the results of this systematic review and meta-analysis, the incidence rate of frailty in patients with CHF was 41.83%, and age, NYHA functional class, albumin, haemoglobin, cerebrovascular accidents, comorbidity, duration of hospitalization, LVEF, left atrial diameter were associated with frailty in patients with CHF. In previous reports, while some studies have explored the factors that influence frailty in CHF patients, the articles each focused on a single factor, and their conclusions were controversial [32, 33].
Our finding was consistent with the studies conducted by He et al and Meng et al [34, 35], indicating that age was a significant factor associated with frailty in patients with CHF. A systematic review supported this, revealing that older patients with HF were six to seven times more likely to be frail than non-frail individuals [36]. A systematic review also supports this, the risk of frailty increases with age in CHF patients, the older the CHF patients, the higher the risk of frailty [37, 38]. This can be attributed to a decline in activities of daily living, reduced handgrip strength, and slower gait speed that commonly occur with ageing. Combined with the lower activity tolerance of CHF patients and poor immune function, these changes eventually lead to frailty [39]. Ageing is also associated with DNA damage, impaired autophagy and elevated oxidative stress due to mitochondrial dysfunction, which could be considered an accelerated form of frailty in CHF patients [40].
Our research also suggests a strong correlation between a poor NYHA classification and frailty in CHF patients. Some studies [41–43] have demonstrated that changes in cardiac structure and function including elevated B-type natriuretic peptide, abnormal left ventricular structures and decrease in stroke volume worsen frailty. Cardiac function decline contributes to dysfunction of organ systems and functional losses. Meanwhile, patients with poor cardiac function are more likely to restrict their movements, leading to skeletal muscle atrophy, which increases the likelihood of developing frailty [7]. Studies have shown that engaging in physical activity [44, 45], such as resistance training, can potentially reverse or delay the muscle wasting process. This suggests that implementing rehabilitation training during a patient’s stable phase to improve functional capacity may help prevent or slow down the progression of frailty.
The systematic review and meta-analysis highlighted that nutritional management and nutritional support may be beneficial to reducing the risk of frailty in patients with CHF. We found that albumin, haemoglobin and MAMC were protective factors against frailty in individuals with heart failure. In contrast, CHF patients with malnutrition risk were more inclined to be frail than their counterparts. Chaves and colleagues [46] conducted a cross-sectional study that mildly low and low-normal haemoglobin levels were independently associated with increased frailty risk in community-dwelling older women, and cardiovascular diseases such as CHF decreased the ability of compensatory reactions to anaemia, leading to increased susceptibility. Additionally, malnutrition can lead to a decrease in protein synthesis and muscle mass, causing the risk of and progression of sarcopenia, which is an important aetiological factor in the development of frailty [47].
Frailty is considered the accumulation of biological deficits, and multiple chronic diseases are manifestations of biological deficit accumulation [48]. In this study, the CIRS-CI scale, comorbidity score and number of comorbidities contributed to frailty in patients with CHF, and the results were similar to the findings of Vetrano and colleagues [49]. Tazzeo et al found that in multimorbidity patterns, cardiovascular diseases, and neuropsychiatric diseases were more strongly associated with physical frailty than other diseases in both cross-sectional and longitudinal dimensions [50]. Our results also demonstrated that cerebrovascular accidents had a significant effect on the risk of frailty in CHF. Hence, it is crucial to establish an early warning mechanism for HF patients with cerebrovascular diseases and implement appropriate interventions to prevent frailty. CHF patients with multiple conditions usually rely on polypharmacy. Gnjidic and Hilmer have indicated that [51] there are plausible mechanisms by which drugs may affect the development of frailty, including weight loss, balance disorders, poor nutritional status, and functional deterioration. Observing the possible benefits of reducing polypharmacy and improving the precise medication rate to delay frailty need to be studied further.
In contrast to previous studies, our study did not find a significant difference in gender between frail and non-frail individuals. Conversely, this contradicts the majority of previous studies which reported a higher proportion of frailty among females than males [35, 52]. However, it is important to note that our study had strict limitations on the articles included for analysis, which may have affected our ability to observe gender differences in frailty over long periods of time. Future research using different study designs may provide further insights into the relationship between gender and frailty.
Previous studies showed [53, 54] a relationship between increased inflammation and frailty regardless of the presence of significant clinical comorbidity. However, the C-reactive phase protein also showed nonsignificant results on frailty in patients with HF in our study. Ribeiro et al [24] collected elevated sensitivity C-reactive protein by immunoturbidimetry analysis, and Noda analysed the relationship between log CRP with frailty [22]. The difference in the detection method and calculation method between the three studies brings heterogeneity.
Psychiatric disease conditions such as depression and anxiety have a negative effect on physical frailty in patients with HF in the findings of Fried et al [55], but depression was not associated with frailty in our study. A relatively small sample size would most likely have resulted in the finding of a nonsignificant association between frailty and depression.
In addition, the influence of haemoglobin and LVEF on frailty in CHF patients in our review should be treated with careful caution. The unstability of the results due to the limited number of studies with heterogeneity call for more robust evidence. there was possible evidence of publication bias in our systematic review and meta-analysis. Although we tried to minimize potential publication bias by a comprehensive collection of the factors reported to affect frailty in CHF patients. Reasons for this bias including firstly the nature of observational study design, the limited number of studies with heterogeneity were the origin of publication bias. Secondly, favourable results were more likely to be reported also caused the risk. Thirdly, the included population was not set as the elderly in the study of Valdiviesso et al [13], and the age of participants ranged from 24 to 81 years, which increased the likelihood of publication bias.
Limitations and strengths
This review features participants from a diverse range of study designs, geographical regions, and ethnic backgrounds, and we combine descriptive analysis with meta-analysis, to comprehensively recognize the influencing factors affecting frailty in CHF patients. Since we only retrieved published literature, articles published in English and Chinese, and the document collection may be incomplete. Future studies should consider other languages and grey literature. In addition, the relatively small size of some studies [29, 30], the moderate risk bias of two articles [25, 31], the heterogeneity in study design and the evidence of publication bias calls for robust, better-designed, and uniform standard studies. Third, the influencing factors included in the studies were scattered, so a meta-analysis of some of the influencing factors could not be performed in this study.