Relationships between cystatin C- and creatinine-based eGFR in Japanese rural community- dwelling older adults with sarcopenia

Association of blood biomarkers with frailty-A mapping review

Frailty describes a geriatric syndrome characterized by an increased vulnerability. Although a variety of potential blood-based biomarkers have been discussed for its characterization, a reliable protocol considering blood-based biomarkers for this purpose is still missing. However, a comprehensive overview on these biomarkers is necessary to understand potential molecular pathways to frailty. We, therefore, performed a mapping review to identify those blood-based biomarkers most consistently associated with frailty in community-dwelling older adults as well as possible analytical gaps according to the available literature. A proposed weighted correlation index (CI) describing the direction and consistency of the association considering the number of available publications as well as the size of the study populations was calculated for each biomarker. Overall, 72 manuscripts were critically reviewed reporting on a total of 82 biomarkers. The most consistent positive association with at least 3 articles addressing the respective biomarker in unadjusted and fully adjusted models was shown for interleukin 6 (IL-6), high-sensitivity C-reactive protein (hs-CRP), neopterin, white blood cells count, glycated hemoglobin A1c (HbA1c) and sex hormone binding-globuline (SHBG) with a CI ≥ 0.7, while for negative association hemoglobin, 25-hydroxy vitamin D, free testosterone in men and albumin with a CI ≤ -0.7 were identified.

Serum uric acid/creatinine ratio and osteoporosis in the elderly: a NHANES study

Background

Osteoporosis (OP) is a metabolic bone disorder that is of significant concern to the elderly. However, few studies have investigated the correlation between the serum uric acid to creatinine ratio (UA/Cr) and OP in elderly individuals. This research seeks to examine the connection between UA/Cr levels and OP in older adults.

Methods

Data on participant information for the study was obtained from four cycles of the NHANES database. Multivariable logistic regression was employed to examine the correlation between UA/Cr and OP, adjusting for potential confounders such as age, gender, and race. The diagnostic efficacy of UA/Cr for OP was evaluated utilizing ROC curves.

Results

Multivariable logistic regression analysis showed that serum UA/Cr levels were significantly lower in individuals with OP than in those without OP. (OR = 0.83 [0.76, 0.91], P < 0.001). Subgroup analyses indicated a stronger association in men (OR = 0.77 [0.64, 0.94], P = 0.009) and women (OR = 0.85 [0.76, 0.95], P < 0.003). Furthermore, multivariable logistic regression analyses by ethnicity revealed that this association was significant solely among Non-Hispanic Whites (OR = 0.78 [0.68, 0.90], P < 0.001). The area under the ROC curve (AUC) for UA/Cr in predicting OP was higher than that for SUA alone, indicating superior predictive value.

Conclusion

A higher UA/Cr level within the normal range is associated with a lower risk of OP, providing insights for its diagnosis and risk assessment.

Association between psoas muscle mass index and bone mineral density in patients undergoing hemodialysis

Patients undergoing dialysis are at risk of osteoporosis and sarcopenia because of mineral and bone disorders or malnutrition. Additionally, maintaining muscle mass is important to prevent osteoporosis. The psoas muscle mass index (PMI) was recently used to evaluate muscle mass. However, few studies have evaluated the association between the PMI and bone mineral density (BMD); therefore, we examined the association between PMI and BMD in the femoral neck (FN) of 80 patients (45 males, age, 71 (60-76) years; dialysis duration, 74 (36-140) months) undergoing hemodialysis. FN-BMD was measured using dual-energy X-ray absorptiometry, and PMI was evaluated using psoas muscle areas on computed tomography. FN-BMD and PMI were significantly higher in males than in females. In a correlation analysis, sex, BMI, serum creatinine levels, HbA1c levels, and PMI were positively correlated with FN-BMD, whereas age, history of bone fracture, difficulty in walking and bone-specific alkaline phosphatase level were negatively correlated. In the multivariate regression analysis using clinical factors significantly correlated to FN-BMD, including PMI, both sex (standardized coefficient: 0.249, p = 0.028) and PMI (standardized coefficient: 0.249, p = 0.038) were extracted. Multivariable linear regression analysis using PMI and traditional osteoporosis factors revealed that PMI was significantly and independently associated with FN-BMD (standardized coefficient: 0.308, p = 0.010). In conclusion, PMI was positively associated with FN-BMD. Attention should be paid to the possibility of decreased BMD with decreased muscle mass.

Oral Frailty and Its Relationship with Physical Frailty in Older Adults: A Longitudinal Study Using the Oral Frailty Five-Item Checklist

BACKGROUND/OBJECTIVES

Oral frailty, first identified in Japan in 2014, refers to a state between healthy oral function and severe decline, marked by minor issues, such as tooth loss and chewing difficulties. The oral frailty five-item checklist (OF-5) enables non-dental professionals to evaluate oral frailty using five key indicators: remaining teeth count, chewing difficulties, swallowing difficulties, dry mouth, and articulatory oral skills. Limited studies exist.

METHODS

This study examined the relationship between oral and physical frailties in older adults and assessed the prognosis of physical frailty using the OF-5. Participants aged ≥65 years were recruited from the frail elderly in the Sasayama-Tamba area, Hyogo, Japan, and their physical function was assessed in terms of grip strength, walking speed, and skeletal muscle mass. Blood markers, such as cystatin C, an indicator of renal function, were also analyzed.

RESULTS

A cross-sectional analysis indicated that oral frailty was correlated with reduced muscle mass, walking speed, and physical function. Women had lower hemoglobin and albumin levels and a greater prevalence of frailty than men. Longitudinal analysis revealed that initial OF-5 scores predicted increased physical frailty after 2-3 years, especially in those with higher baseline scores. The OF-5 was a significant factor for frailty progression in both sexes.

CONCLUSIONS

These results suggest that early detection of oral frailty via the OF-5 may be useful in preventing the progression of overall frailty in older adults.

Unlocking diagnosis of sarcopenia: The role of circulating biomarkers - A clinical systematic review

Sarcopenia, the gradual loss of muscle mass, strength, and function with age, poses a significant risk to older adults, making early diagnosis crucial for preventing disability and enhancing quality of life. Biomarkers are vital for the early detection, monitoring progression, and assessing the efficacy of treatments for sarcopenia, offering a detailed evaluation of muscle health. This systematic review examined the clinical potential of circulating biomarkers in sarcopenia by analyzing studies up to May 2024 from PubMed, Scopus, Web of Science. A total of 45 studies involving 641,730 patients were reviewed, revealing notable biomarker differences between sarcopenic and non-sarcopenic individuals. Sarcopenic patients exhibited lower levels of certain microRNAs, hemoglobin, albumin, and anti-inflammatory factors, alongside higher levels of red and white blood cells, pro-inflammatory factors, growth factors, matrix proteins, free thyroxine, cortisol, and adiponectin. Additionally, they had lower levels of irisin, free triiodothyronine, and insulin, with reduced phosphatidylcholines and elevated spermidine. The studies were generally of fair to good quality, but due to heterogeneity, a meta-analysis was not feasible. The review underscores the need for standardized biomarkers and diagnostic criteria and suggests that improving outcomes for sarcopenic patients may involve addressing inflammation, metabolic, and hormonal issues through nutrition, medication, and exercise.

Impaired Muscle Parameters in Individuals With Premature Ovarian Insufficiency: A Pilot Study

Context

Although bone loss is a recognized consequence of premature ovarian insufficiency (POI), the impact on skeletal muscle health is less well-defined.

Objective

To compare muscle mass and function parameters between women with POI and controls.

Methods

Cross-sectional study from a tertiary health network and community between 2017 and 2023. Participants were women aged 20 to 40 years with POI associated with Turner syndrome (TS; n = 11) and spontaneous normal karyotype POI (s-POI; n = 7) compared with age- and body mass index (BMI)-matched controls (n = 45).

Results

All women with POI (mean age 28.70 ± 5.58) were using hormone therapy. Appendicular lean mass (ALM)/total fat mass and ALM/ BMI was lower in the POI group. Height-adjusted muscle mass parameters did not differ between groups. Compared with controls, women with TS and s-POI had lower muscle strength (TS 19.72 ± 4.89; s-POI 22.73 ± 5.35; controls 28.67 ± 5.65 kg; P < .001) and muscle quality (TS 11.09 ± 2.06; s-POI 10.89 ± 2.01; controls 14.10 ± 1.99 kg/kg; P < .001). Higher C-reactive protein levels, higher depression scores, and lower sex-steroid and physical activity levels were observed in women with POI (P < .05). Creatinine/cystatin C ratio, insulin-like growth factor-1, and transthyretin did not differ between groups.

Conclusion

Despite hormone therapy usage, women with POI exhibited compromised muscle parameters compared with age-matched controls. Potential contributory factors were identified. Further research is required to clarify pathophysiology and inform management strategies.

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.

Urban-rural differences in the prevalence and associated factors of sarcopenia: A systematic review and meta-analysis

BACKGROUND

Loss of muscle mass, muscle strength, and/or physical performance due to aging is known as sarcopenia. Regardless of how serious this illness is, no single diagnostic criteria have been established. Much research conducted recently has demonstrated differences between built environment characteristics (i.e., urban and rural) and the occurrence of sarcopenia; however, variations in sarcopenia prevalence in urban-rural areas around the world have been reported by fewer studies. This work sought to determine how sarcopenia prevalence varied between urban and rural areas and to explore the associated influencing factors.

METHODS

Using the pertinent MESH phrases and free words, PubMed, Web of Science, Embase, and China national knowledge infrastructure databases were scanned for core sarcopenia literature up to February 26, 2023. Observational studies involving urban-rural patients with sarcopenia published in Chinese and English, and assessing muscle mass via computed tomography, bioelectrical impedance, or dual-energy X-ray absorption techniques were considered as inclusion criteria. The meta-analysis involved analysis of the urban-rural prevalence in subgroups by diagnostic criteria, tools for assessing muscle mass and study type, as well as the factors related to urban-rural differences in the occurrence of sarcopenia. STATA version 11.0 was used to perform the statistical analysis.

RESULTS

Sixty-six articles involving 433,091 participants were included for analysis: of which 27 were analyzed for both prevalence and related factors whereas 39 were for only prevalence. The meta-analysis revealed the prevalence of sarcopenia to be 0.18 (95 % CI 0.14-0.22), with significant heterogeneity (P < 0.001; I2 = 99.9 %). Moreover, the prevalence of sarcopenia in urban group [0.16 (I2 = 99.9 %, 95 % CI 0.1-0.22)] was lower than in rural group [0.2 (I2 = 99.6 %, 95 % CI 0.16-0.25)] and urban-rural group [0.21 (I2 = 97.5 %, 95 % CI 0.16-0.25)]. Besides, the factors significantly associated with sarcopenia in urban-rural areas were age, gender, BMI, malnutrition, physical activity, and polypharmacy. There was significant heterogeneity between these factors and the association of sarcopenia.

CONCLUSIONS

Sarcopenia is associated with aspects of the built environment, and studies have revealed that sarcopenia is more common in rural than in urban populations with influencing factors including age, gender, BMI, poor nutrition, insufficient physical activity, and polypharmacy. The lack of uniform diagnostic criteria makes a robust and comprehensive assessment difficult. Therefore, the formation of certain universal and standardized diagnostic criteria will help future research on sarcopenia.

Diagnostic test accuracy of serum creatinine and cystatin C-based index for sarcopenia: a systematic review and meta-analysis

BACKGROUND

Sarcopenia is an important prognostic factor, but its optimal screening methods remain challenging. Several new indices developed based on serum creatinine (Cr) and cystatin C (CysC) have been proposed to be diagnostic biomarkers for sarcopenia screening.

OBJECTIVE

This review aimed to evaluate the diagnostic accuracy of serum Cr- and CysC-based indices for sarcopenia diagnosis.

METHODS

We systematically searched MEDLINE, EMBASE, SCIE and SCOPUS from inception to 2 April 2023. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. A bivariate random-effects model was used to synthesise the pooled sensitivity, specificity and area under the curves of the summary receiver operating characteristic (SROC-AUC).

RESULTS

We retrieved 936 publications and included 16 studies with 5,566 participants (mean age ranged: 51.0-78.4 years, 50.2% men). The prevalence of sarcopenia ranged from 7.8 to 69.5%. All included studies presented a moderate to high risk of bias. The serum Cr- and CysC-based indices showed moderate diagnostic accuracy for sarcopenia (pooled sensitivity: 0.67, 95% CI 0.57-0.75; pooled specificity: 076, 95% CI 0.67-0.83; pooled SROC-AUC: 0.78, 95% CI 0.74-0.81). The Cr/CysC ratio is the most widely studied index, followed by the Cr × eGFRcys index. Overall, both indicators had satisfactory and comparable performance in screening sarcopenia.

CONCLUSION

Serum Cr- and CysC-based indices showed moderate diagnostic accuracy for sarcopenia. The most studied indices-the Cr/CysC ratio and Cr × eGFRcys index-had comparable diagnostic accuracy for evaluating sarcopenia and may serve as surrogate markers for sarcopenia. However, further validation is required to verify these findings.

Blood biomarkers for sarcopenia: A systematic review and meta-analysis of diagnostic test accuracy studies

Biomarkers are emerging as a potential tool for screening or diagnosing sarcopenia. We aimed to summarize the current evidence on the diagnostic test accuracy of biomarkers for sarcopenia. We comprehensively searched Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials up to January 2023 and only included diagnostic test accuracy studies. We identified 32 studies with 23,840 participants (women, 58.26%) that assessed a total of 30 biomarkers. The serum creatinine to cystatin C ratio (Cr/CysC) demonstrated a pooled sensitivity ranging from 51% (95% confidence interval [CI] 44-59%) to 86% (95% CI 70-95%) and a pooled specificity ranged from 55% (95% CI 38-70%) to 76% (95% CI 63-86%) for diagnosing sarcopenia defined by five different diagnostic criteria (11 studies, 7240 participants). The aspartate aminotransferase to alanine aminotransferase ratio demonstrated a pooled sensitivity of 62% (95% CI 56-67%) and a pooled specificity of 66% (95% CI 60-72%) (3 studies, 11,146 participants). The other 28 blood biomarkers exhibited low-to-moderate diagnostic accuracy for sarcopenia regardless of the reference standards. In conclusion, none of these biomarkers are optimal for screening or diagnosing sarcopenia. Well-designed studies are needed to explore and validate novel biomarkers for sarcopenia.

Comparison of the serum creatinine- and cystatin-C-based indices as screening biomarkers for sarcopenia in community-dwelling older adults

BACKGROUND

Several creatinine- and cystatin-C-based indices have been proposed as sarcopenia predictors. This study aimed to compare serum creatinine- and cystatin-C-based indices as screening biomarkers for sarcopenia in community-dwelling older adults.

METHODS

A cross-sectional study was conducted on 945 participants aged between 70 and 84 years (men=47.5%; mean age=76.0 ± 3.9 years) from the Korean Frailty and Aging Cohort Study. The serum creatinine-to-cystatin-C ratio estimated glomerular filtration rate (eGFR) ratio (eGFRcystatin-C/eGFRcreatinine), sarcopenia index (serum creatinine × eGFRcreatinine), predicted skeletal muscle mass index (pSMI), and total body muscle mass index (TBMM) were compared.

RESULTS

The prevalence of sarcopenia was 19.9% in men and 14.0% in women. The pSMI and TBMM showed higher correlations with appendicular lean mass and grip strength in men (pSMI: rs=0.356-0.701, p < 0.001; TBMM: rs=0.320-0.730, p < 0.001) and women (pSMI: rs=0.299-0.669, p < 0.001; TBMM: rs=0.256-0.658, p < 0.001) than the other indices. The area under the receiver operating characteristic curves (AUC) of the serum indices for predicting sarcopenia showed the highest accuracy for pSMI (men: AUC=0.77, p < 0.001; women: AUC=0.71, p < 0.001). After adjusting for potential confounders, pSMI was associated with the likelihood of sarcopenia in both men (odds ratio [OR]=0.170; 95% confidence interval [CI]=0.103-0.279) and women (OR=0.167; 95% CI=0.087-0.321).

CONCLUSION

pSMI and TBMM accurately determined sarcopenia than the other indices. Furthermore, a higher pSMI was strongly associated with a decreased risk of sarcopenia compared to TBMM. These findings suggest pSMI as a potential biomarker for sarcopenia screening in community-dwelling older adults.

Association between the ratio of serum creatinine to cystatin C and bone mineral density in middle-aged and older adults: a cross-sectional study from NHANES database

OBJECTIVE

To investigate the association between creatinine to cystatin C ratio (CCR) and bone mineral density (BMD) in middle-aged and older adults.

METHODS

This cross-sectional study investigated participants aged 50-85, using National Health and Nutrition Examination Survey (NHANES) data from 1999 to 2002. The correlation between CCR and total BMD was assessed by multivariate linear regression models, using stratified analysis by age, sex and race (Mexican American, other Hispanic, non-Hispanic White, non-Hispanic Black, and other race) to distinguish various special populations.

RESULTS

Among 2992 patients, multiple regression models revealed a significant positive correlation between CCR and total BMD: model 1, 0.030 (95% confidence interval [CI] 0.029, 0.031); model 2, 0.009 (95% CI 0.008, 0.010); model 3, 0.010 (95% CI 0.009, 0.013). After controlling for all covariates, a positive correlation was observed between CCR and total BMD in both men and women, and was further strengthened in older age groups. When stratifying by race, the positive correlation was most significant among 'other Hispanic' participants; there was no significant correlation among those of 'other race'.

CONCLUSIONS

A positive correlation was demonstrated between CCR and total BMD in middle-aged and older adults aged 50-85 years, with the most significant positive correlation in the older 'other Hispanic' population. No significant correlation was observed among participants of 'other race'.

Renal dysfunction, malignant neoplasms, atherosclerotic cardiovascular diseases, and sarcopenia as key outcomes observed in a three-year follow-up study using the Werner Syndrome Registry

Werner syndrome is an adult-onset progeria syndrome that results in various complications. This study aimed to clarify the profile and secular variation of the disease. Fifty-one patients were enrolled and registered in the Werner Syndrome Registry. Their data were collected annually following registration. A cross-sectional analysis at registration and a longitudinal analysis between the baseline and each subsequent year was performed. Pearson's chi-squared and Wilcoxon signed-rank tests were used. Malignant neoplasms were observed from the fifth decade of life (mean onset: 49.7 years) and were observed in approximately 30% of patients during the 3-year survey period. Regarding renal function, the mean estimated glomerular filtration rate calculated from serum creatinine (eGFRcre) and eGFRcys, which were calculated from cystatin C in the first year, were 98.3 and 83.2 mL/min/1.73 m2, respectively, and differed depending on the index used. In longitudinal analysis, the average eGFRcre for the first and fourth years was 74.8 and 63.4 mL/min/1.73 m2, showing a rapid decline. Secular changes in Werner syndrome in multiple patients were identified. The prevalence of malignant neoplasms is high, and renal function may decline rapidly. It is, therefore, necessary to carry out active and detailed examinations and pay attention to the type and dose of the drugs used.

Association between the ratio of serum creatinine to cystatin C and bone mineral density in Chinese older adults patients with type 2 diabetes mellitus

Background

The ratio of creatinine to cystatin C (Cre/CysC), a marker of muscle function and muscle mass, can be used to predict sarcopenia in different populations. Since sarcopenia is closely associated with osteoporosis, this study investigated the association between Cre/CysC and bone mineral density (BMD) in patients with type 2 diabetes mellitus (T2DM).

Method

This cross-sectional study included 391 Chinese patients with T2DM. General information, biochemical indicators, and the BMD of lumbar spine (LS), femoral neck (FN), and total hip (TH) were measured.

Results

Pearson correlation analysis showed that Cre/CysC was significantly positively correlated with the BMD of LS (r = 0.170, p = 0.001), FN (r = 0.178, p < 0.001), and TH (r = 0.205, p < 0.001). The results of stepwise linear regression suggested that Cre/CysC was the only biochemical predictor of the BMD at three sites (LS: β = 0.137, p = 0.01; FN: β = 0.097, p = 0.038; TH: β = 0.145, p = 0.002).

Conclusion

In older patients with T2DM, high Cre/CysC value is independently positively associated with BMD and hence, Cre/CysC may serve as a valuable marker of osteoporosis.

Relationships between cystatin C and creatinine‐based eGFR with low tongue pressure in Japanese rural community‐dwelling older adults

Background

Sarcopenia is prevalent in patients with chronic kidney disease (CKD), which is defined as a low estimated glomerular filtration rate (eGFR). It has been reported that oral hypofunction characterized by decreased tongue pressure is related to sarcopenia. Although there are several previous reports regarding the association of renal dysfunction with oral hypofunction characterized by low tongue pressure, the association between tongue pressure and renal function is not fully understood.

Methods

This cross‐sectional study included 68 men aged 79.0 ± 4.8 years and 145 women aged 77.3 ± 5.4 years from a rural area in Hyogo Prefecture, Japan. We examined the relationships between cystatin C‐based CKD (CKDcys), creatinine‐based CKD (CKDcre), ratio of cystatin C‐based GFR (eGFRcys) divided by creatinine‐based GFR (eGFRcre): eGFRcys/eGFRcre, and tongue pressure in community‐dwelling older adults.

Results

Tongue pressure was significantly lower in participants with CKDcys than in those without CKDcys in men and women. However, there were no significant differences in tongue pressure with or without CKDcre. Tongue pressure was significantly lower in participants with eGFRcys/eGFRcre <1.0, than in those with eGFRcys/eGFRcre ≧ 1.0 in men. According to the receiver operating characteristic analysis, the optimal cut‐off value of tongue pressure for the presence of CKDcys was 36.6kPa, area under the curve (AUC) 0.74 (specificity 54.8%, sensitivity 84.6%) in men and 31.8kPa, AUC 0.65 (specificity 67.3%, sensitivity 60.5%) in women.

Conclusions

CKDcys but not CKDcre is associated with low tongue pressure. In addition, a lower eGFRcys/eGFRcre ratio is a useful screening marker of low tongue pressure in community‐dwelling older adults.

Comparison of Creatinine and Cystatin C to Estimate Renal Function in Geriatric and Frail Patients

The aim of this study was to compare estimated glomerular filtration rate (eGFR) with creatinine (eGFRcrea) and cystatin C (eGFRcys) in geriatric and frail patients. A retrospective, cross-sectional study was performed at a geriatric clinic in Stockholm (n = 95). The revised Lund−Malmö equation was used to calculate eGFRcrea and the Caucasian-Asian-Pediatric-Adult (CAPA) equation was used for eGFRcys. The absolute mean percentage difference between eGFRcrea and eGFRcys was used as a surrogate measure for accuracy in eGFR. Other outcome measures were consistency expressed in Lin’s concordance correlation coefficient and the proportion of consistent staging of renal failure. Subgroup analyses were performed with regard to frailty (according to Clinical Frailty Scale) and age. eGFRcys estimated lower GFR than eGFRcrea across the entire study population as well as in all subgroups (p < 0.05). Difference between the estimates increased with increasing frailty (r2 = 0.15, p < 0.01), but was not significantly affected by age (r2 = 0.004, p = 0.55). In conclusion, eGFRcys was significantly lower compared to eGFRcrea in geriatric and frail patients. Moreover, frailty had greater impact than age on the accuracy of eGFR. However, this study cannot determine if any of the estimates are preferable over the other in this patient group.

The ratio of creatinine and cystatin C estimated glomerular filtration rates as a surrogate marker in patients with hepatocellular carcinoma undergoing hepatic resection

BACKGROUND

The ratio of creatinine and cystatin C estimated glomerular filtration rates (eGFRcre/eGFRcys) is significantly positively correlated with sarcopenia. However, there are no published reports on the relationship between eGFRcre/eGFRcys and long-term prognosis in patients after hepatic resection for hepatocellular carcinoma (HCC).

METHODS

157 patients who had undergone curative hepatic resection for HCC were retrospectively reviewed. Cystatin C levels were measured in serum samples that had been frozen after collection at surgery. We aimed to investigate the significance of cystatin C in prognostic value following hepatic resection for HCC.

RESULTS

The best cut-off eGFRcre/eGFRcys value for overall survival after hepatic resection for HCC was 1.0025. High eGFRcre/eGFRcys was significantly associated with poor liver function, low skeletal muscle mass, large tumor size, large ascitic volume, worse overall and recurrence-free survival. The eGFRcre/eGFRcys was significantly related to severe recurrence patterns (multiple liver recurrences, distant metastasis).

CONCLUSIONS

Preoperative eGFRcre/eGFRcys can predict overall and recurrence-free survival in HCC patients undergoing hepatic resection. The eGFRcre/eGFRcys is a simple and reliable surrogate marker that indicate for eligibility for hepatic resection for HCC.

A Novel Application of Serum Creatinine and Cystatin C to Predict Sarcopenia in Advanced CKD

Sarcopenia is highly prevalent in patients with advanced chronic kidney disease (CKD), yet a reliable serum index has not been established. The product of serum creatinine and the estimated glomerular filtration rate based on cystatin C (Cr×eGFRcys) was recently proposed as a sarcopenia index (SI), approximately to 24-h filtered creatinine through the glomerulus. We aimed to evaluate the diagnostic validity of the novel SI in advanced CKD. In 297 patients with non-dialysis stage 3b-5 CKD, aged 68.8 ± 12.9 years, the total skeletal muscle mass (SMM), handgrip strength (HGS), and usual gait speed were assessed. Sarcopenia was defined based on the Asian Working Group for Sarcopenia 2019 consensus update. The prevalence of sarcopenia in this cohort was 20.2%. The SI correlated moderately with SMM (r = 0.503, P &lt; 0.001), HGS (r = 0.508, P &lt; 0.001), and gait speed (r = 0.381, P &lt; 0.001); the independency of the SI with three muscle metrics was confirmed after extensive adjustment. For sarcopenia prediction, the SI had acceptable discriminative powers in males [area under the receiver operating characteristic curve (AUC) 0.646, 95% confidence interval (CI) 0.569–0.718] and females (AUC 0.754, 95% CI 0.670–0.826). In males, the best cut-off was 53.9, which provided 71.1% sensitivity, 58.0% specificity, 32.9% positive predictive value (PPV), and 87.4% negative predictive value (NPV); in females, the best cut-off was 45.8, which provided 81.8% sensitivity, 62.3% specificity, 31.0% PPV, and 94.3% NPV. In conclusion, Cr×eGFRcys could be served as a surrogate marker for sarcopenia and may be helpful for sarcopenia screening in advanced CKD. Further studies are needed to expand our investigation.

Estimation of Muscle Mass Using Creatinine/Cystatin C Ratio in Japanese Community-Dwelling Older People

OBJECTIVES

Sarcopenia is defined as a combination of low skeletal muscle mass index (SMI), weak muscle strength, and reduced physical function. Recently, many studies have reported that the creatinine/cystatin C ratio (Cr/CysC) is useful for evaluating muscle mass. We designed a cross-sectional study with separate model development and validation groups to develop a prediction equation to estimate bioimpedance analysis (BIA)-measured SMI with Cr/CysC.

DESIGN

The current study was a retrospective cross-sectional study.

SETTING AND PARTICIPANTS

The model development group included 908 subjects (288 men and 620 women) from the Frail Elderly in the Sasayama-Tamba Area (FESTA) study, and the validation group included 263 subjects (112 men and 151 women) from participants in the medical checkup program at the Anti-Aging Center in Ehime Prefecture.

MEASURES

Multivariate regression analysis indicated that age, hemoglobin (Hb), body weight (BW), and Cr/CysC were independently associated with SMI in both men and women. The SMI prediction equation was developed as follows: Men:4.17-0.012×Age+1.24×(Cr/CysC)-0.0513×Hb+0.0598×BW Women:3.55-0.00765×Age+0.852×(Cr/CysC)-0.0627×Hb+0.0614×BW RESULTS: The SMI prediction equation was applied to the validation group and strong correlations were observed between the BIA-measured and predicted SMI (pSMI) in men and women. According to the receiver operator characteristic (ROC) analysis, the areas under the curve were 0.93 (specificity 89.0%, sensitivity 87.2%) among men and 0.88 (specificity 83.6%, sensitivity 79.6%) among women for using pSMI to identify low SMI in the model development group. The pSMI also indicated high accuracy in ROC analysis for low SMI in the validation group. The Bland-Altman plot regression showed good agreement between BIA-measured and pSMI.

CONCLUSIONS AND IMPLICATIONS

Our new prediction equation to estimate SMI is easy to calculate in daily clinical practice and would be useful for diagnosing sarcopenia.

Serum indices based on creatinine and cystatin C predict mortality in patients with non-dialysis chronic kidney disease

Serum indices based on creatinine and cystatin C, including creatinine/cystatin C ratio (Cr/CysC), ratio and difference of estimated glomerular filtration rate (eGFR) based on cystatin C and creatinine (eGFRcys/eGFRcre and eGFR_Diff), and serum creatinine × eGFRcys, are recently identified serum markers for sarcopenia. We aimed to evaluate the association between these serum indices and mortality in patients with chronic kidney disease (CKD). A single-center retrospective cohort study included 1141 adult patients with stage 1–5 CKD between 2016 and 2018. Basic characteristics, comorbidities, laboratory parameters, and serum creatinine and cystatin C values were obtained. Patients were followed up until death, dialysis, transfer to another hospital, or end of the study. The median age (interquartile range) of our participants was 71 (62–81) years. During a median follow-up of 39 months, 116 (10.2%) patients died. Compared to the survivor group, Cr/CysC, eGFRcys/eGFRcre, eGFR_Diff, and Cr × eGFRcys were all lower in the non-survivors (p < 0.001 for all). The receiver operating characteristic curves of serum indices for predicting mortality showed that all four indices had significant discriminative power. Based on the Cox proportional hazard models, lower values of four serum indices, both as continuous and categorical variables, independently predicted mortality. Our findings suggest that low serum indices of Cr/CysC, eGFRcys/eGFRcre, eGFRDiff, and Cr × eGFRcys are independent indicators of mortality in patients with non-dialysis CKD.

Estimation of kidney function in patients with primary neuromuscular diseases: is serum cystatin C a better marker of kidney function than creatinine?

BACKGROUND

Using serum creatinine leads to an overestimation of kidney function in patients with primary neuromuscular disorders, and reduced kidney function may remain undetected. Cystatin C (CysC) could provide a better estimation.

AIM

To evaluate the precision, accuracy, and bias of two creatinine-, one cystatin C-based and one combined equation to estimate glomerular filtration rate (eGFR) in patients with primary neuromuscular disease.

PATIENTS AND METHODS

Of the 418 patients initially identified at the out-patient clinic, data on kidney function was obtained for 145 adult patients (age 46 ± 14 years, BMI 26 ± 6 kg/m²) with primary neuromuscular disease. Kidney function was measured by iohexol clearance, and blood samples for serum creatinine and CysC were drawn simultaneously. Bias was defined as the mean difference between eGFR and measured iohexol clearance, and accuracy as the proportion of eGFRs within ± 10% (P10) of measured clearance.

RESULTS

Kidney function (iohexol clearance) was 81 ± 19 (38-134) ml/min/1.73m². All equations overestimated kidney function by 22-60 ml/min/1.73m². eGFR CysC had the lowest bias overall 22 (95% CI 20-26) ml/min/1.73m² also at all levels of kidney function we evaluated (at 30-59 ml/min/1.73m² bias was 27 (95% CI 21-35), at 60-89 it was 25 (95% CI 20-28) and at ≥ 90 it was 12 (95% CI 7-22)). eGFR CysC also had the best accuracy in patients with reduced kidney function (P10 was 5.9% at 30-59 ml/min/1.73m²).

CONCLUSIONS

Cystatin C-based estimations of kidney function performed better than creatinine-based ones in patients with primary neuromuscular disease, but most importantly, all evaluated equations overestimated kidney function, especially in patients with reduced kidney function. Therefore, kidney function should be measured by gold-standard methods when precision and accuracy are needed.