1. Introduction
By 2050, over 2.1 billion people will be aged 60 years or older, comprising 22% of the global population.1 Chronic diseases are the major health threats to the elderly,2 thereby increasing the complexity of healthcare needs among older adults. In 2015, the World Health Organization (WHO) introduced the concept of “intrinsic capacity (IC),” defined as an individual’s composite ability across 5 domains: cognition, psychology, vitality, locomotion, and sensory capacity.3 This concept marks a shift from disease treatment alone to holistic functional maintenance. The WHO recommends initial screening across these 5 domains using a brief IC screening tool,4 followed by the application of domain-specific evaluation instruments for detailed measurement. Despite the growing variety of measurement tools, significant differences in indicators used across studies may limit the comparability of results.5
In recent years, IC has increasingly become a key indicator for predicting health outcomes in elderly adults.6 Numerous studies have demonstrated that IC is closely associated with falls, quality of life, and mortality rates.7,8,9 IC is gradually providing new entry points for the long-term health management of elderly patients with chronic diseases.10 Therefore, analyzing the status and determinants of IC in elderly patients with chronic diseases is key to promoting healthy aging.
2. Intrinsic capability of elderly patients with single chronic disease
Elderly patients with chronic diseases show heterogeneous patterns of IC decline across different disease types. For instance, a study of 701 elderly individuals with cardiovascular disease showed that they had lower baseline IC levels compared to the general community-dwelling elderly population.11 This may be attributed to the pathological and physiological burdens of the disease. Among elderly stroke patients in the recovery phase, overall IC tends to be at a moderately low level, particularly in the cognitive dimension.12 It was found similarly among elderly patients with coronary heart disease.13 Additionally, research on elderly hypertensive patients indicates a general decline in IC, involving multidimensional simultaneous impairment.14 In summary, elderly patients with common chronic diseases such as stroke, coronary heart disease, and hypertension generally exhibit moderate to low levels of IC, often in a state of decline. This decline is multifaceted. A study of 240 elderly patients with type 2 diabetes found that the overall incidence of IC decline was 47.5%, with particular deterioration in the cognitive and psychological domains.15 This may be related to age and diabetes-related complications, both of which are risk factors for reduced IC.16 Elderly patients undergoing hemodialysis also commonly experience significant IC decline, particularly affecting vitality, locomotion, and psychological dimensions.17 This is related to the fact that these patients commonly face physical functional decline, such as sarcopenia, reduced mobility, malnutrition, and a state of low-grade inflammation. These factors exacerbate the overall IC decline.18,19,20 A comparable decline has been noted among elderly cancer patients receiving chemotherapy.21 Elderly adults with a single chronic disease commonly experience different impairments in IC. Therefore, incorporating IC assessment into the management of elderly patients with chronic conditions is essential. Such assessments can support the development of individualized care plans, particularly for the most frequently affected cognitive, psychological, and vitality domains. Future research should prioritize longitudinal studies to better understand IC trajectories and causal mechanisms, to develop disease-specific intervention measures.
3. Intrinsic capability of elderly patients with multiple chronic conditions
Multiple chronic conditions (MCCs) are highly prevalent among older adults and have a pronounced cumulative adverse effect on functional independence.22 Furthermore, interactions between different diseases can amplify their collective negative impact on IC. Increased treatment burdens and complex medication regimens further undermine patients’ capacity to maintain function.23 Research indicates a clear relationship between MCCs and IC in older adults. Arthritis-gastritis or respiratory system diseases have a more significant negative impact on IC. This may be due to associated factors, such as chronic pain, systemic inflammation, limited mobility, and nutritional risks.24 However, existing studies have limitations. For instance, some important age-related conditions such as osteoporosis, were not included in certain analyses. Further analysis reveals that different disease combination patterns variably affect IC, contributing to its multi-dimensional deterioration.24,25 For example, among community-dwelling elderly diabetes patients with multimorbidity, sensory impairment is the most prominent (37.1%), often associated with diabetic retinopathy and hearing loss. Locomotion impairment affects 26.3% of patients and is frequently linked to reduced muscle strength and balance.26 In summary, MCCs significantly aggravate multidimensional impairment IC in the elderly, with distinct patterns based on disease combinations. Based on these findings, healthcare providers should implement structured IC assessments in geriatric clinics to identify high-risk patients early. Subsequently, integrated care models tailored to specific disease combination patterns should be developed to address the holistic functional needs of this population.
4. The impact of IC on health outcomes in elderly patients with chronic disease
The level of IC directly influences disease progression and key health outcomes in elderly patients with chronic disease. These outcomes include functional limitations, falls, disability, and hospitalization rates.27,28,29 For example, patients with osteoporosis are more likely to experience activity limitations and have an increased risk of falls.30 Similarly, stroke survivors frequently exhibit cognitive impairment and multidimensional functional limitations.31 Overall, patients with chronic disease are particularly susceptible to insufficient IC. This insufficiency often leads to a substantial increase in health-care resource consumption.24 More critically, the decline in IC is a significant predictor of all-cause mortality and cardiovascular mortality among elderly patients with chronic disease.11,32,33 In summary, the deterioration of IC in this population worsens their quality of life and amplifies the overall disease burden. While these observational studies are valuable for establishing association, their inherent design limits their capacity to definitively establish causality between IC decline and subsequent health outcomes. Therefore, dynamic monitoring and targeted intervention for IC should be prioritized in chronic disease management. The primary goal should be to design and evaluate effective integrated care models aimed at mitigating IC decline and its consequential impact on health outcomes.34
5. Factors influencing IC in elderly patients with chronic disease
The decline of IC arises from complex interactions among physiological, psychological, and social factors. In elderly patients with chronic disease, this process is often accelerated by the pathological progression of the disease, the cumulative effects of comorbidities, and the burdens associated with treatment.
5.1. Physiological factors
Physiological factors constitute the core foundation influencing IC. Inflammatory responses,35 oxidative stress,36 metabolic disorders,37 and impaired neurological function38 related to chronic diseases can directly contribute to the decline of IC. For instance, patients with chronic kidney disease frequently experience reduced muscle mass and strength due to chronic inflammation, manifesting as decreased physical strength and vitality.39 Research indicates that the level of brain-derived neurotrophic factor (BDNF) at the neuromuscular junction is positively correlated with IC. Higher BDNF levels are associated with a lower risk of IC impairment. Furthermore, oxidative stress has been identified as a partial mediator in the protective mechanism of BDNF against IC decline.36 Additionally, comorbidity and polypharmacy can trigger drug interactions and adverse reactions, thereby diminishing patients’ functional reserves.40 However, it is important to note that evidence for many specific mechanisms often derives from cross-sectional or case-control studies. Future research should employ longitudinal designs with repeated measures of both biomarkers and IC to better elucidate causal pathways. Consensus-building efforts are also needed to standardize core biomarker panels.
5.2. Psychological factors
Psychological factors significantly influence the maintenance of IC. Elderly patients with chronic diseases experience depression, increased cognitive burden, and diminished self-efficacy.41 Depression accelerates memory decline, while memory decline exacerbates depression.42 It also found that middle-aged and elderly diabetes patients with low self-efficacy levels often lack confidence in adhering to medication regimens and monitoring blood glucose levels, indirectly accelerating functional decline.43 The research is strengthened by the use of validated psychometric scales, yet it is limited by its heavy reliance on self-report, which can be influenced by cultural and cognitive biases.42 Moreover, many studies focus on single psychological constructs, potentially overlooking synergistic effects, such as those between depression and low self-efficacy. Therefore, integrating standardized psychological screening into chronic disease management and providing targeted psychological support are crucial for maintaining IC in this population.
5.3. Social factors
Social factors provide essential external support for maintaining IC. They influence IC through pathways such as promoting activity participation, strengthening family relationships, providing social support, and determining economic status.11,44 Social environment and lifestyle play crucial roles, particularly in resource-poor areas and among populations with weak social support systems, where the risk of IC decline is significantly heightened. High levels of education and economic wealth can foster healthy lifestyles and encourage active social engagement, thereby enhancing quality of life and delaying IC decline.11,45 However, it is difficult to disentangle whether social factors directly preserve IC or are proxies for other advantages like better nutrition and earlier access to healthcare. For policymakers, it is vital to fund community-based programs that reduce social isolation and develop social care policies that actively support the functional well-being of older adults with chronic conditions.
6. Conclusions
IC significantly influences both the quality of life and clinical outcomes in elderly patients with chronic diseases. The factors affecting IC include physiological, psychological, and social dimensions. Although this study provides an overview of the current understanding of IC in elderly adults with chronic diseases, the existing evidence base remains relatively limited. Studies to date vary widely in research design and different chronic disease populations, making it challenging to draw definitive conclusions. Future research should prioritize longitudinal and interventional studies to elucidate the characteristics and trajectories of IC in this population. Expanding high-quality evidence in this area will be essential for advancing the practical integration of IC into clinical assessment and intervention strategies.