In this cohort study, we included participants from CHARLS and NHANES to investigate the associations between CKM syndrome stages and the risks of adverse outcomes among middle-aged and older adults. Our findings indicated that CKM syndrome stages, particularly the advanced stages, were significantly associated with increased risks of geriatric syndromes, including disability, frailty, falls, and hospitalization. In addition, CKM syndrome stages were also associated with cause-specific mortality, including CVD, malignant neoplasm, respiratory disease, and other causes. After adjusting for CKM components, the positive associations retained, indicating that CKM syndrome had health-related impacts beyond those of its component disorders. These results highlighted CKM syndrome as a systemic health condition contributing to multiorgan dysfunctions, underscoring its relevance in gerontology, geriatrics, major chronic diseases and broader multidisciplinary contexts.
Previous studies focused on CKM components consisting of risk factors, rather than the whole construct of CKM syndrome, regarding to geriatric syndromes. Giltay et al. illustrated that CKM components consisting of BMI, hypertension, diabetes, and serum cholesterol, were predictive of functional disability34. Similarly, Cui et al. reported that higher cardiovascular risk burdens, as assessed by the Framingham general cardiovascular risk score, increased the risk of disability and accelerated its progression over time17. As for frailty, CKM components, including obesity, hypertension, dyslipidemia, diabetes, increased the risk of frailty35. Moreover, cardiovascular disorders, such as stroke and coronary artery disease, were associated with falls36. A consensus was reached to incorporate cardiovascular assessments in falls risk screening and prevention for older adults at risk of falls37. In contrast, our study employed the CKM syndrome construct, encompassing both CVD risk factors and CVD events comprehensively. We found that the CKM stages were associated with increased risks of geriatric syndromes with dose-effect relationships. Therefore, the CKM assessment could refine prediction model for risks stratification of geriatric syndromes. It highlighted the need to promote the concept of CKM staging construct and its education to geriatric community, clinician, and older adults to prevent these geriatric syndromes. Optimizing CKM health could help to enhance the geriatric health conditions and reduce social and healthcare burdens. In addition, these results confirmed the validity and robustness of the CKM staging construct, which enabled researchers and clinicians to categorize the individuals along a continuum of increasing risk in practice.
We found that CKM syndromes predicted cause-specific mortality, including CVD, cancer, respiratory disease and other cause. Prior studies had reported similar associations through CKM components or risk factors38. For instance, Lau et al. reported that a 10-year ASCVD risk score and natriuretic peptide concentrations were associated with increased risk of incident cancer39. Meanwhile, Mercedes et al. demonstrated a cardiovascular disease risk score was strongly associated with cancer mortality, such as lung, breast, and colon cancers40. Similarly, respiratory diseases shared CKM risk factors, such as hypertension, dyslipidemias41, diabetes and metabolic syndrome. In our study, we applied CKM staging construct to explore its associations with both CVD mortality and non-CVD mortality (e.g., cancer, respiratory disease). The CKM stages were linked to CVD mortality with highest risks, especially the advanced stages. It supported the CKM staging construct’s objective to prevent CVD events and mortality from early CKM stages. These associations between CKM syndrome and mortality of major chronic diseases underscored CKM syndrome as a systemic health condition impacting multiorgan systems and overall health. Prediction of the future aging-associated outcomes (e.g., geriatric syndromes, major chronic diseases), and its clinical utility validated the CKM construct and its substantial applications42. Screening for each CKM stage could help predict risks of aging-associated, CVD and non-CVD outcomes related to CKM syndrome. These results advocated for the use of CKM assessment in preventing major chronic diseases among middle-aged and older adults.
Our study demonstrated the incident geriatric syndromes and mortality followed advanced CKM stages, marked by subclinical and clinical CVD. Therefore, the primary objective was to prevent geriatric syndromes and major age-related chronic diseases among middle-aged and older adults in advanced CKM stages. Enhanced health care, such as intensified preventive therapies and pharmacological medications, was necessary to prevent CKM progression and mitigate adverse outcomes. The prevalence of early stages and advanced stages of CKM syndrome accounted for approximately 60% and 30% in CHARLS, respectively, highlighting its severe burden in the general population. The CKM staging construct emphasized early detection of CKM-related changes to support prevention efforts. For instance, lifestyle modification and weight loss can address excess or dysfunctional adiposity in early CKM stages.
Within the CKM construct, it recognized the importance of the relationships between kidney health and cardiovascular health. Impaired kidney function was linked with elevated risks of CVD and geriatric syndromes43,44. Risk prediction equations of kidney function could inform clinical management and prevention of CKM syndrome and geriatric syndrome. Moreover, it started to emphasize the social determinants of health in assessments for CKM risk factors7. The social needs, including financial strain, education and mental health, played a critical role in CKM health and healthy aging. Therefore, evaluation of kidney health and social risk factors were critical in risk screening, prediction and prevention of geriatric syndromes.
Several limitations should be noted in this study. Firstly, subclinical CVDs and CVDs were determined by predicted risks and self-reports, respectively, which may introduce recall bias and affect associations. Secondly, we focused on disability, frailty, falls, hospitalization, and mortality as outcomes; further studies should consider other metrics, such as cognitive decline, physical function declines, hip fracture and other functional metrics. Lastly, while cause-specific mortality was assessed, evidence regarding disease incidence remained limited for CKM syndrome.
In conclusion, the findings highlighted CKM syndrome as a systemic health disorder affecting overall health among middle-aged and older adults, advocating for its broader application in multidisciplinary research, diverse clinical and community settings, especially the gerontology research and geriatrics. Application of CKM in geriatrics will enhance geriatric conditions and promote healthy aging to alleviate the social and healthcare burdens. These results provided substantial evidence to support the validity and robustness of the CKM staging construct, and its goal to prevent CVD events and mortality.