Sarcopenia index based on serum creatinine and cystatin C is associated with mortality in middle-aged and older adults in Chinese: A retrospective cohort study from the China Health and Retirement Longitudinal Study

Serum creatinine and serum cystatin C as an index of muscle mass in adults

PURPOSE OF REVIEW

Serum creatinine reflects both muscle mass and kidney function. Serum cystatin C has recently been recommended as an additional marker for estimating kidney function, and use of both markers together may provide an index of muscle mass. This review aims to describe the biological basis for and recent research examining the relationship of these markers to muscle mass in a range of adult populations and settings.

RECENT FINDINGS

This review identified 67 studies, 50 of which had direct measures of muscle mass, and almost all found relationships between serum creatinine and cystatin C and muscle mass and related outcomes. Most studies have been performed in older adults, but similar associations were found in general populations as well as in subgroups with cancer, chronic kidney disease (CKD), and other morbid conditions. Creatinine to cystatin C ratio was the measure examined the most often, but other measures showed similar associations across studies.

SUMMARY

Measures of serum creatinine and cystatin C together can be an index of muscle mass. They are simple and reliable measures that can be used in clinical practice and research. Further study is needed to determine actionable threshold values for each measure and clinical utility of testing and intervention.

Biomarkers of chronic kidney disease in older individuals: navigating complexity in diagnosis

Chronic kidney disease (CKD) in older individuals is a matter of growing concern in the field of public health across the globe. Indeed, prevalence of kidney function impairment increases with advancing age and is often exacerbated by age-induced modifications of kidney function, presence of chronic diseases such as diabetes, hypertension, and cardiovascular disorders, and increased burden related to frailty, cognitive impairment and sarcopenia. Accurate assessment of CKD in older individuals is crucial for timely intervention and management and relies heavily on biomarkers for disease diagnosis and monitoring. However, the interpretation of these biomarkers in older patients may be complex due to interplays between CKD, aging, chronic diseases and geriatric syndromes. Biomarkers such as serum creatinine, estimated glomerular filtration rate (eGFR), and albuminuria can be significantly altered by systemic inflammation, metabolic changes, and medication use commonly seen in this population. To overcome the limitations of traditional biomarkers, several innovative proteins have been investigated as potential, in this review we aimed at consolidating the existing data concerning the geriatric aspects of CKD, describing the challenges and considerations in using traditional and innovative biomarkers to assess CKD in older patients, highlighting the need for integration of the clinical context to improve biomarkers' accuracy.

Lower serum creatinine to cystatin C ratio associated with increased incidence of frailty in community-dwelling elderly men but not in elderly women

BACKGROUND

Sarcopenia has been reported to play an important role in frailty syndrome. The serum creatinine/serum cystatin C ratio (Scr/Cys C ratio) has recently been recognized as a valuable indicator for assessing sarcopenia. However, few studies have examined the association between serum creatinine/serum cystatin C ratio and frailty. The objective of this study is to investigate the relationship between the serum creatinine/serum cystatin C ratio and frailty among older adults residing in the community.

METHODS AND MATERIALS

A Total of 1926 community-dwelling older adults aged ≥ 60 years in the 2011 waves of the China Health and Retirement Longitudinal Study (CHARLS) were included. The participants' frailty status was determined using a 39 item frailty index (FI), which classified individuals as "robust" (FI ≤ 0.1), "pre-frailty" (0.1 < FI < 0.25), or "frailty" (FI ≥ 0.25). The Scr/Cys C ratio was determined by dividing the serum creatinine level (mg/dL) by the cystatin C level (mg/L). The one-way analysis of variance(ANOVA) and Chi-squared test (χ2)were applied to compare the differences between the 3 groups. Both linear regression and logistic regression models were used to further investigate the relationship between Scr/Cys C ratio and frailty.

RESULTS

After adjusting for potential confounding factors, the study revealed that participants in the Q1 quartile of Scr/Cys C ratio had increased odds of frailty (Q1vs.Q4: OR = 1.880, 95% CI 1.126-3.139, p = 0.016) compared with those in the Q4 quartile group. In fully adjusted logistic regression models, male participants in the Q2 quartile of Scr/Cys C ratio were significantly correlated with higher odds of pre-frailty (Q2 vs.Q4: OR = 1.693, 95%CI 1.040-2.758, p = 0.034). However, this correlation was not observed in females (OR = 0.984, 95% CI 0.589-1.642, p = 0.950,). Additionally, the study observed an increase in both the frailty index and the incidence of frailty as age increased in both males and females.

CONCLUSION

Among community-dwelling older adults, lower Serum creatinine to cystatin C ratio were found to be associated with increased odds of frailty prevalence in males.

Adherence Behaviors and Related Factors Among Elderly Hypertensive Patients in China: Evidence from the China Health and Retirement Longitudinal Study

Background

Non-adherence or partial adherence is the main reason for poor therapeutic effect of hypertension. This paper aims to assess adherence behaviors and related factors among elderly hypertensive patients in China.

Methods

Participants aged ≥60 years, with hypertension, and with complete data in 2018 interviews of the China Health and Retirement Longitudinal Study (CHARLS) were included. The adherence behaviors included medication, blood pressure monitoring and the combined adherence behaviors. Referring to the social-ecological theory, correlates of adherence behaviors were divided into three layers, namely demographic characteristics, health behaviors, living environment and retirement. Univariate and multivariable logistic regression models were performed to identify factors of adherence behaviors.

Results

The prevalence of medication adherence (76.58%) was higher than that of blood pressure monitoring adherence (20.08%), and the full adherence rate was 18.53%. Self-rated health status, smoking status, living area, and health education status were detected to be associated with medication adherence and blood pressure monitoring adherence (all p < 0.05). Gender, sleep duration, health examination, and physical exercise were also detected to be associated with blood pressure monitoring adherence (all p < 0.05). Self-rated health status and health education status were detected to be associated with partially and fully adherence, while age, living area, and life satisfaction were detected to be associated with partially adherence, smoking status, sleep duration, health examination, and pension reliance were detected to be associated with fully adherence (all p < 0.05).

Conclusion

Our study reveals the poor adherence behaviors of elderly hypertensive patients in China. This is most evident among those who were male, 60-69 years old, living in rural areas, self-reported being healthier, those without health examination and health education. Targeting these vulnerable populations, we suggest to strengthen health education, increase the publicity of basic public health services and enhance the self-management ability of hypertensive patients.