Genome-Wide Search Links Senescence-Associated Secretory Proteins With Susceptibility for Coronary Artery Disease in Mouse and Human

Advanced age is an independent risk factor for coronary artery disease (CAD), the leading global cause of mortality. Senescent vascular cells in the atherosclerotic plaques exhibit senescence-associated secretory phenotype (SASP). How SASP contributes to atherosclerosis and CAD, however, remains unclear. Here, we integrated RNA-array datasets of senescent human coronary arterial endothelial cells (HCAECs) and aortic smooth muscle cells (HASMCs) as well as genome-wide association data for CAD. We identified 26 genes from HCAECs and 6 genes from HASMCs related to SASP and CAD in both in-house and published datasets. Of which, Cystatin C (CST3), a CAD susceptibility gene, was found to be expressed in both HCAECs and HASMCs, thus, it was prioritized for further investigation. We demonstrated it was significantly elevated in senescent vascular cells, aged arteries, and early atherosclerosis. In vitro experiments showed that CST3 enhances the monocyte-endothelial cell adhesion. Additionally, ligand-receptor pairing analyses revealed two important pathways, COL4A1-ITGA1 and LPL-LRP1 pathways, linked to the critical processes in the development of atherosclerosis, including cell adhesion, inflammation response, extracellular matrix organization, and lipid metabolism. We further demonstrated a reduced monocyte-endothelial cell adhesion following the knockdown of COL4A1 or ITGA1 and a significantly increased expression of COL4A1, ITGA1, and LPL in arterial intima of aged mice and ApoE-/- mice. Our findings demonstrate that vascular cell-derived SASP proteins increase the CAD susceptibility and identify CST3 functionally contributing to atherosclerosis.

Impact of moderate to vigorous intensity physical activity on change in renal function in patients after acute myocardial infarction

Acute myocardial infarction (AMI) is associated with a decline in renal function. This study aimed to investigate the impact of engaging in moderate to vigorous intensity physical activity (MVPA) for more than 30 min per day on changes in renal function during the first 3 months after AMI onset. A prospective, observational study was conducted, enrolling 87 patients (75 men; average age, 65.2 ± 12.5 years) who had experienced AMI. The cystatin C-based estimated glomerular filtration rate (eGFRcys) was collected at and 3 months after discharge. Daily MVPA was measured using triaxial accelerometers at a threshold of 3.0 Metabolic equivalent of the task for 3 months. Generalized estimating equations (GEE) were applied to evaluate the longitudinal association between the number of days per week of MVPA for 30 min or more and within-patient changes in eGFRcys. The patients were categorized into three groups based on their MVPA engagement days: 0 days (n = 20), 1-2 days (n = 14), and 3-7 days (n = 53) groups. After adjusting for potential confounding variables, GEE analysis revealed that the eGFRcys slope over 3 months was significantly higher in the 3-7 days group than in 0 days group (B = 2.9, (95% confidence interval: 1.5-4.2), p < 0.001). Similar results were obtained when MVPA time thresholds were set to 40 and 60 min. These findings suggest a significant positive effect of engaging in MVPA for 30 min or more for 3-7 days per week in the improvement of renal function after AMI onset.

Cystatin C is a predictor for long-term All-Cause and Cardiovascular Mortality in US Adults with Metabolic Syndrome

OBJECTIVE

This study examined the relationship between Cystatin C (CysC) levels and all-cause, CVD, and cancer mortality in US metabolic syndrome (MetS) patients.

METHODS

The 1999-2002 National Health and Nutrition Examination Survey (NHANES) prospective cohort research included 1,980 MetS participants. To assess CysC levels and all-cause, CVD, and cancer mortality, fitted curves, Kaplan-Meier survival curves, cox regression analysis, and ROC curves were performed.

RESULTS

During a mean follow-up of 15.3 ± 5.4 years, a total of 819 deaths occurred. The fitted and Kaplan-Meier survival curves revealed that greater CysC levels were linked to higher all-cause, CVD, and cancer mortality rates (P<0.05). After adjusting for variables, CysC level was associated with all-cause, CVD, and cancer mortality at 1.63 (1.42-1.88), 1.53 (1.19-1.95), and 1.53 (1∼2.32), respectively (P<0.05). Later tertile models showed consistent results. High CysC tertile participants showed higher risk of all-cause mortality (HR 1.87; 1.43-2.45), CVD mortality (HR 1.97, 1.15∼3.38), and cancer mortality (HR 1.72, 1.01∼2.91) compared to those in the lowest tertile (P<0.05). Subgroup studies by sex and other characteristics confirmed the findings. CysC demonstrated the higher predictive efficacy across mortality outcomes, followed by eGFR, outperforming Urea nitrogen, Creatinine, Uric acid, and CRP. CysC alone exhibited substantial predictive value for all-cause (AUC 0.773; P<0.05) and CVD mortality (AUC 0.726; P<0.05). Combining CysC with age enhanced the predictive value for all-cause mortality to 0.861 and CVD mortality to 0.771 (P<0.05).

CONCLUSION

MetS patients with elevated CysC levels have a higher risk of all-cause, CVD, and cancer death. CysC may predict MetS all-cause and CVD mortality.

Inflammatory depression is associated with selective glomerular hypofiltration

BACKGROUND

Systemic low-grade inflammation may be a pathophysiological mechanism in a subtype of depression. In this study we investigate a novel candidate mechanism of inflammatory depression - Selective Glomerular Hypofiltration Syndromes (SGHS) - which are characterized by a reduced estimated glomerular filtration rate (eGFR) based on cystatin C (cysC) relative to eGFR based on creatinine (crea). SGHS have been associated with increased blood levels of pro-inflammatory markers, but have never been investigated in a sample of depressed individuals.

METHOD

The prevalence of SGHS was compared between 313 patients with difficult-to-treat depression and 73 controls. Since there is no single established eGFRcysC/eGFRcrea-ratio cut-off to define SGHS, several cut-offs were investigated in relation to a depression diagnosis, inflammation, and symptom severity. Plasma inflammatory markers tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin (IL)-6, IL-8, and IL-10 were available from 276 depressed patients. We examined mediation effects of IL-6 on the relationship between SGHS and depression.

RESULTS

Depressed patients were more likely to have SGHS compared to controls defining SGHS as either eGFRcysC/eGFRcrea-ratio < 0.9 (33.2 % vs 20.5 %, p = 0.035) or < 0.8 (15.7 % vs 5.5 %, p = 0.023). Lower eGFRcysC/eGFRcrea-ratio was associated with higher levels of inflammatory markers in depressed patients. IL-6 partly mediated the relationship between SGHS and depression.

CONCLUSION

This is the first study to demonstrate a link between SGHS and inflammatory depression. If replicated in independent and longitudinal cohorts, this may prove to be a relevant pathophysiological mechanism in some cases of depression that could be targeted in future intervention and prevention studies.

Limitations of U25 CKiD and CKD-EPI eGFR formulae in patients 2-20 years of age with measured GFR > 60 mL/min/1.73 m2-a cross-sectional study

BACKGROUND

When applying Pierce U25 formula for estimating glomerular filtration rate (eGFR), we observed a higher proportion of eGFR < 90 mL/min/1.73 m2 (chronic kidney disease (CKD) stage 2). We compared agreement and accuracy of the Pierce U25 (ages 2-25), Pottel (ages 2-100), and CKD-EPI (ages 18-100) formulae to GFR measurements.

METHODS

Post hoc analysis of the three eGFRs compared to 367 99m technetium-diethylene-triamine penta-acetic acid (99Tc DTPA) GFR measurements (240 patients) using 3 sampling points and Brockner/Mørtensen correction (body surface area calculation based on ideal weight) on simultaneous serum creatinine and cystatin C measurements.

RESULTS

Overall, the U25 formula performed well with a Spearman r of 0.8102 (95% confidence interval 0.7706 to 0.8435, p < 0.0001) while diagnostic accuracy was low in patients with normal mGFR. The U25 formula reclassified 29.5% of patients with normal mGFR as CKD stage 2; whereas the average of the modified Schwartz formula based on serum creatinine and the Filler formula based on cystatin C, only over-diagnosed CKD stage 2 in 8.5%, 24.5% within 10% and 62.7% within 30%. We therefore combined both. The average Schwartz/Filler eGFR had 36.5% of results within 10%, 84.7% within 30%, and normal mGFR accuracy was 26.8%, 63.9% for 10% and 30%, respectively, outperforming the CKD-EPI and Pottel formulae.

CONCLUSIONS

The Pierce U25 formula results correlated well with mGFR < 75 mL/min/1.73 m2. Over the entire GFR range, accuracy was better for patients with a higher mGFR, when averaging the combined Schwartz/Filler formulae. More work is needed to prospectively confirm our findings in other centers.

The diagnostic performance of Cr/CysC for sarcopenia and its predictive value on clinical outcomes in hospitalized older patients: a prospective cohort study

PURPOSE

The utilization of the creatinine-to-cystatin C ratio (Cr/CysC) represents an innovative method for predicting sarcopenia. Our objectives encompassed the evaluation of sarcopenia diagnostic accuracy for Cr/CysC, SARC-F, SARC-CalF, the combination of Cr/CysC and SARC-CalF, and the Ishii score, as well as an exploration of the predictive value of Cr/CysC concerning clinical outcomes within hospitalized older individuals.

METHODS

We employed receiver operating characteristic (ROC) curves and calculated areas under the curves (AUCs) to assess the diagnostic accuracy. Furthermore, we applied univariate and multivariate Cox proportional-hazard models to calculate the hazard ratio (HR) and 95% confidence interval (CI) of risk factors affecting prognosis.

RESULTS

Our study included 312 participants, comprising 167 men and 145 women, with an average age of 71 years. Among males, the AUCs for Cr/CysC, SARC-F, SARC-CalF, the combination of Cr/CysC and SARC-CalF, and the Ishii score were 0.717 [95% CI 0.642-0.784], 0.669 (95% CI 0.592-0.739), 0.845 (95% CI 0.781-0.896), 0.882 (95% CI 0.823-0.926), and 0.938 (95% CI 0.890-0.969), respectively. In females, the AUCs for Cr/CysC, SARC-F, SARC-CalF, the combination of Cr/CysC and SARC-CalF, and the Ishii score were 0.706 (95% CI 0.625-0.779), 0.631 (95% CI 0.547-0.710), 0.763 (95% CI 0.686-0.830), 0.789 (95% CI 0.714-0.853), and 0.898 (95% CI 0.837-0.942), respectively. After adjusting for age, sex, physical exercise, smoking, drinking, hypertension, coronary heart disease (CHD), chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD), and cancer, sarcopenia identified by Cr/CysC (adjusted HR = 2.176, 95% CI 1.062-4.460, P = 0.034) was independently associated with poor overall survival in hospitalized older patients.

CONCLUSIONS

Cr/CysC has satisfactory diagnostic accuracy for sarcopenia diagnosis and predictive value for poor outcomes in hospitalized older patients. The combination of Cr/CysC and SARC-CalF may provide a more accurate screening for sarcopenia and the Ishii score may be the most accurate clinical method for detecting sarcopenia.

Prospective validation of an equation based on plasma cystatin C for monitoring the glomerular filtration rate in children treated with cisplatin or ifosfamide for cancer

We recently proposed an equation to estimate the glomerular filtration rate (GFR) in children with cancer based on plasma cystatin C and serum creatinine levels together with body weight (the "CysPed equation"). The current clinical study reports a prospective evaluation of this equation in 18 children treated by nephrotoxic chemotherapy. The CysPed equation resulted in less bias and greater precision compared to two equations previously proposed equations by Schwartz, with or without plasma cystatin C. Moreover, the decrease in GFR due to chemotherapy was clearly identified by the CysPed equation. This equation may be used to monitor the renal function in childhood cancer units.

Extending the cystatin C based EKFC-equation to children - validation results from Europe

BACKGROUND

A new cystatin C based European Kidney Function Consortium (EKFCCysC) equation was recently developed for adults, using the same mathematical form as the previously published full age spectrum creatinine based EKFC-equation (EKFCCrea). In the present study the cystatin C based EKFC-equation is extended to children, by defining the appropriate cystatin C rescaling factor QCysC.

METHODS

Rescaling factor QCysC for cystatin C was defined as: a) 0.83 mg/L, exactly as it was defined for young adults in the adult equation, and b) a more complex QCysC-age relationship based on 4th degree cystatin C-age polynomials after evaluation of data from Uppsala, Stockholm and Canada and aggregated data from Germany. The EKFCCysC equation was then validated in an independent dataset in European children (n = 2,293) with measured GFR, creatinine, cystatin C, age, height and sex available.

RESULTS

The EKFCCysC with the simple QCysC-value of 0.83 had a bias of -7.6 [95%CI -8.4;-6.5] mL/min/1.73 m2 and a P30-value of 85.8% [95%CI 84.4;87.3] equal to the EKFCCysC with the more complex 4th degree QCysC-value. The arithmetic mean of the EKFCCrea and EKFCCysC with the simple QCysC of 0.83 had a bias of -4.0 [95%CI -4.5;-3.1] mL/min/1.73 m2 and P30 of 90.4% [95%CI 89.2;91.6] similar to using the more complex 4th degree QCysC-polynomial.

CONCLUSION

Using exactly the same QCysC of 0.83 mg/L, the adult EKFCCysC can easily be extended to children, with some bias but acceptable P30-values. The arithmetic mean of EKFCCrea and EKFCCysC results in bias closer to zero and P30 slightly over 90%.

Acute Kidney Injury Prediction Model Using Cystatin-C, Beta-2 Microglobulin, and Neutrophil Gelatinase-Associated Lipocalin Biomarker in Sepsis Patients

Introduction

AKI is a frequent complication in sepsis patients and is estimated to occur in almost half of patients with severe sepsis. However, there is currently no effective therapy for AKI in sepsis. Therefore, the therapeutic approach is focused on prevention. Based on this, there is an opportunity to examine a panel of biomarker models for predicting AKI.

Material and Methods

This prospective cohort study analysed the differences in Cystatin C, Beta-2 Microglobulin, and NGAL levels in sepsis patients with AKI and sepsis patients without AKI. The biomarker modelling of AKI prediction was done using machine learning, namely Orange Data Mining. In this study, 130 samples were analysed by machine learning. The parameters used to obtain the biomarker panel were 23 laboratory examination parameters.

Results

This study used SVM and the Naïve Bayes model of machine learning. The SVM model's sensitivity, specificity, NPV, and PPV were 50%, 94.4%, 71.4%, and 87.5%, respectively. For the Naïve Bayes model, the sensitivity, specificity, NPV, and PPV were 83.3%, 77.8%, 87.5%, and 71.4%, respectively.

Discussion

This study's SVM machine learning model has higher AUC and specificity but lower sensitivity. The Naïve Bayes model had better sensitivity; it can be used to predict AKI in sepsis patients.

Conclusion

The Naïve Bayes machine learning model in this study is useful for predicting AKI in sepsis patients.

Lower glomerular filtration rate after mild stroke induces cognitive impairment by causing endothelial dysfunction

The incidence of post stroke cognitive impairment (PSCI) is high in patients with mild stroke (MIS), and the risk factors and mechanism are uncertain. Increased cystatin C (CysC) levels after stroke may reflect lower glomerular filtration rate (GFR) and renal impairment. Previous studies have suggested endothelial dysfunction (ED) is closely related to renal impairment and cognitive impairment, respectively. We aimed to observe whether lower GFR estimated by CysC after MIS leaded to a high incidence of PSCI, and the role of ED in this process. 256 patients were enrolled in this prospective observational study. Renal function was assessed using GFR estimated by serum CysC. Endothelial function was evaluated by reactive hyperemia index (RHI) which calculated automatically by peripheral arterial tonometry (PAT). The cognitive function at baseline and 3 months was evaluated by MoCA score, and MoCA score ≤ 26 indicates the presence of PSCI. Spearman correlation analysis and linear regression were conducted to explore the factors affecting ED. Univariate and multivariate analysis was used to identify the independent risk factors of PSCI. The receiver operating characteristic (ROC) curve was applied to explore the optimal cutoff value of the independent risk factors levels for predicting PSCI. A total of 141 patients (55.1%) suffered from ED. Multiple linear regression analysis showed that there was a strong linear correlation between eGFRcys and RHI (p < 0.001). At the three-month follow-up, a total of 150 (58.6%) patients had been diagnosed with PSCI. Multivariate logistic regression analysis showed that RHI was an independent factor affecting the occurrence of PSCI (p < 0.05). ROC curve showed that the area under the curve was 0.724, and the optimal cut-off value of RHI was 1.655, with the sensitivity and specificity for PSCI were 72.7% and 73.6%, respectively. The lower eGFRcys level after MIS was significantly associated with ED, and ED may mediate the higher incidence of PSCI at 3 months after MIS.

Cystatin C Outperforms Creatinine in Predicting Cefepime Clearance in Pediatric Stem Cell Transplant Recipients

Pediatric hematopoietic stem cell transplant (HSCT) patients are at risk of developing both sepsis and altered kidney function. Cefepime is used for empiric coverage post-HSCT and requires dose adjustment based on kidney function. Since cefepime's antimicrobial efficacy is determined by the time free concentrations exceed bacterial minimum inhibitory concentration (MIC), it is important to assess kidney function accurately to ensure adequate concentrations. Serum creatinine (SCr) is routinely used to estimate glomerular filtration rate (eGFR) but varies with muscle mass, which can be significantly lower in HSCT patients, making SCr an inaccurate kidney function biomarker. Cystatin C (CysC) eGFR is independent of muscle mass, though steroid use increases CysC. Objectives of this study were to describe how eGFR impacts cefepime pharmacokinetic/pharmacodynamic (PK/PD) target attainment in pediatric HSCT patients, to investigate which method of estimating GFR (SCr, CysC, combined) best predicts cefepime clearance, and to explore additional predictors of cefepime clearance. Patients admitted to the pediatric HSCT unit who received ≥2 cefepime doses were prospectively enrolled. We measured total cefepime peak/trough concentrations between the second and fourth cefepime doses and measured SCr and CysC if not already obtained clinically within 24h of cefepime samples. eGFRs were calculated with Chronic Kidney Disease in Children U25 equations. Bayesian estimates of cefepime clearance were determined with a pediatric cefepime PK model and PK software MwPharm++. Simple linear regression was used to compare cefepime clearance normalized to body surface area (BSA) to BSA-normalized SCr-, CysC-, and SCr-/CysC-eGFRs, while multiple linear regression was used to account for additional predictors of cefepime clearance. For target attainment, we assessed the percentage of time free cefepime concentrations exceeded 1x MIC (%fT>1x MIC) and 4x MIC (%fT>4x MIC) using a susceptibility breakpoint of 8 mg/L for Pseudomonas aeruginosa. We enrolled 53 patients (ages 1 to 30 years, median 8.9 years). SCr- and CysC-eGFRs were lower in patients who attained 100% fT>1xMIC compared to those who did not attain this target: 115 versus 156 mL/min/1.73m2 (p = .01) for SCr-eGFR and 73.5 versus 107 mL/min/1.73m2 (p < .001) for CysC-eGFR. SCr-eGFR was weakly positively correlated with cefepime clearance (adjusted [a]r2= 0.14), while CysC-eGFR and SCr-/CysC-eGFR had stronger positive correlations (ar2 = 0.30 CysC, ar2 = 0.28 combo. There was a weak, significant linear association between increasing CysC-eGFR and decreased %fT>1xMIC (ar2 = 0.32) and %fT>4xMIC (ar2 = 0.14). No patients with a CysC-eGFR >120 mL/min/1.73 m2 achieved 100% fT>1xMIC or 50% fT>4x MIC. In multiple regression models, underlying diagnosis of hemoglobinopathy (in all models) and being pretransplant (in SCr and combined models) were associated with increased cefepime clearance, while concomitant use of calcineurin inhibitors was associated with decreased cefepime clearance in all models. Overall, the combo-eGFR model with timing pretransplant, hemoglobinopathy, and use of calcineurin inhibitors had the best performance (ar2 = 0.63). CysC-based eGFRs (CysC alone and combined) predicted cefepime clearance better than SCr-eGFR, even after considering steroid use. Increasing CysC eGFR correlated with decreased probability of PD target attainment, raising concerns for underdosing at high eGFRs. CysC should be included when estimating kidney function to provide adequate dosing of cefepime in pediatric HSCT patients.

Evaluation of eGFR methods in a sub-Saharan African community-based pediatric population

BACKGROUND

Accurate assessment of the estimated glomerular filtration rate (eGFR) plays a pivotal role in the early detection, management, and optimal medication dosing for chronic kidney disease (CKD). However, validation of eGFR, utilizing cystatin C-based equations, is limited in African children and adolescents with CKD. We evaluate the agreement of eGFR equations incorporating both cystatin C and creatinine in this specific population.

METHODS

This community-based study assessed CKD in children (2-15 years) using cystatin C and serum creatinine. eGFR agreement with the reference was evaluated with Bland-Altman plots, ROC curves, and Lin's CCC, using the Under-25 serum creatinine-cystatin C equation as the reference standard. Pairwise ROC comparisons assess the statistical differences in estimation equation agreement.

RESULTS

Among 666 children (mean age, 7.8 ± 3.8 years; 48.6% male), CKD prevalence was 11.6% (95% CI, 9.2-14.2%). Notably, the Chehade equation, using combined biomarkers, aligned best with the reference, displaying the lowest mean deviation (- 0.59; 95% CI, - 1.19 to 0.01), superior agreement (P10, 91.0%; P30, 96.70%), and highest discriminatory power (0.989). In contrast, CKD-EPI 2012 cystatin C had the highest mean deviation (- 35.90) and lowest discriminatory power (0.79). Equations combining creatinine and cystatin C (Schwartz, Chehade, Full Age Spectrum) demonstrated strong positive Lin's CCC with CKiD U25 creatinine-cystatin C, while Bouvet showed a notably weak correlation (Lin's CCC, 0.22).

CONCLUSION

In African children with CKD, the Chehade, CKiD Under 25 creatinine-based equations, and the Full Age Spectrum equations show promise for CKD diagnosis. However, a measured GFR is essential to identifying the most accurate eGFR equation in this population.

Correlation between sarcopenia index and cognitive function in older adult women: A cross-sectional study using NHANES data

OBJECTIVES

The Sarcopenia Index (SI) has the potential as a biomarker for sarcopenia, which is characterized by muscle loss. There is a clear association between sarcopenia and cognitive impairment. However, the relationship between SI and cognitive impairment is yet to be fully understood.

METHODS

We employed data extracted from the U.S. National Health and Nutrition Examination Survey (NHANES) spanning the years 1999 to 2002. Our study encompassed individuals aged 65 to 80 who possessed accessible information regarding both SI and cognitive evaluations with a GFR ≥ 90. Cognitive function was assessed using the digit symbol substitution test (DSST). SI was calculated by serum creatinine (mg/dL)/cystatin C (mg/L)*100. Employing multivariate modeling, we estimated the connection between SI and cognitive performance. Furthermore, to enhance the reliability of our data analysis, we categorized SI using tertiles and subsequently calculated the P-value for trend.

RESULTS

After adjustment for potential confounders, we found SI was significantly and positively correlated with cognitive function scores both in older female in the American population [β = 0.160, 95 % confidence interval (CI) 0.050 to 0.271, P = 0.00461]. Similarly, when the total cognitive function score was treated as a categorical variable according to tertiles, higher SI was related to better total cognitive function scores in females [odds ratio (OR) = 3.968, 95 % CI 1.863 to 6.073, P = 0.00025] following adjustment for confounders.

CONCLUSIONS

Higher SI was correlated with a lower prevalence of cognitive impairment among older adult women with normal kidney function.

Renal arterial resistive index versus novel biomarkers for the early prediction of sepsis-associated acute kidney injury

Acute kidney injury (AKI) is a critical complication of sepsis. There is a continuous need to identify and validate biomarkers for early detection. Serum and urinary biomarkers have been investigated, such as neutrophil gelatinase associated lipocalin (NGAL) and cystatin C (Cys C), but their reliability in the intensive care unit (ICU) remains unknown. Renal hemodynamics can be investigated by measuring the renal resistive index (RRI). This study aimed to compare the performance of RRI, serum NGAL (sNGAL), urinary NGAL (uNGAL), and serum Cys C levels as early predictors of the diagnosis and persistence of sepsis-associated AKI. A total of 166 adult patients with sepsis syndrome were enrolled immediately after ICU admission. Biomarkers were measured directly (T1) and on day 3 (T3). RRI was measured directly (T1) and 24 h later (T2). Patients were categorized (according to the occurrence and persistence of AKI within the first 7 days) into three groups: no AKI, transient AKI, and persistent AKI. The incidence rate of sepsis-associated AKI was 60.2%. Sixty-six patients were categorized as in the no AKI group, while another 61 were in transient AKI and only 39 were in persistent AKI. The RRI value (T1 ≥ 0.72) was the best tool for predicting AKI diagnosis (area under the receiver operating characteristic curve, AUROC = 0.905). Cys C (T1 ≥ 15.1 mg/l) was the best tool to predict the persistence of AKI (AUROC = 0.977). RRI (T1) was the best predictive tool for sepsis-associated AKI, while Cys C was the best predictor of its persistence and 28-day mortality.

A case of Duchenne muscular dystrophy recovered from prolonged ischemic kidney injury which emerged with a normal creatinine level

Duchenne muscular dystrophy (DMD) is an inherited disease characterized by progressive degeneration of the skeletal muscles. Renal dysfunction in patients with DMD has recently become more apparent as life expectancy has increased owing to advances in respiratory devices and heart failure therapies. A 23-year-old man with DMD who required nasal tube feeding was referred to our hospital with a 4-month history of renal dysfunction and anemia. The patient's serum creatinine (sCr) level was within the normal range (0.84 mg/dL), but his serum cystatin C level and estimated glomerular filtration rate calculated by cystatin C (5.90 mg/L and 7.5 mL/min/1.73 m2, respectively) indicated severe renal impairment. A urinalysis revealed elevated levels of protein and tubular markers. The patient's hemoglobin and erythropoietin levels indicated renal anemia. Hypotension, a collapsed inferior vena cava, and a poor tube feeding episode suggested that the kidney injury was due to renal ischemia, which progressed to tubulointerstitial kidney injury, an intrinsic kidney injury. The angiotensin-converting enzyme inhibitors and beta-blockers were discontinued, and extracellular fluid was infused. Thereafter, the patient's renal function recovered. Subsequently, the patient's urinary findings and anemia improved. Although advances in cardioprotective agents are expected to improve the prognosis of patients with DMD, it is important to consider that the number of patients with kidney injury due to renal ischemia may increase and that it is difficult to evaluate renal function using sCr level in patients with DMD because of decreased skeletal muscle mass.

Predictive Performance of Neutrophil Gelatinase Associated Lipocalin, Liver Type Fatty Acid Binding Protein, and Cystatin C for Acute Kidney Injury and Mortality in Severely Ill Patients

Background

Acute kidney injury (AKI) is a common condition in severely ill patients associated with poor outcomes. We assessed the associations between urinary neutrophil gelatinase-associated lipocalin (uNGAL), urinary liver-type fatty acid-binding protein (uLFABP), and urinary cystatin C (uCysC) concentrations and patient outcomes.

Methods

We assessed the predictive performances of uNGAL, uLFABP, and uCysC measured in the early phase of intensive care unit (ICU) management and at discharge from the ICU in severely ill patients for short- and long-term outcomes. The primary outcome was the occurrence of AKI during ICU stay; secondary outcomes were 28-day and 1-yr allcause mortality.

Results

In total, 1,759 patients were admitted to the ICU, and 728 (41.4%) developed AKI. Median (interquartile range, IQR) uNGAL, uLFABP, and uCysC concentrations on admission were 147.6 (39.9-827.7) ng/mL, 32.4 (10.5-96.0) ng/mL, and 0.33 (0.12-2.05) mg/L, respectively. Biomarker concentrations on admission were higher in patients who developed AKI and associated with AKI severity. Three hundred fifty-six (20.3%) and 647 (37.9%) patients had died by 28 days and 1-yr, respectively. Urinary biomarker concentrations at ICU discharge were higher in non-survivors than in survivors. The areas under the ROC curve (95% confidence interval) of uLFABP for the prediction of AKI, 28-day mortality, and 1-yr mortality (0.70 [0.67-0.72], 0.63 [0.59-0.66], and 0.57 [0.51-0.63], respectively) were inferior to those of the other biomarkers.

Conclusions

uNGAL, uLFABP, and uCysC concentrations on admission were associated with poor outcomes. However, their predictive performance, individually and in combination, was limited. Further studies are required to confirm our results.

Novel equations incorporating the sarcopenia index based on serum creatinine and cystatin C to predict appendicular skeletal muscle mass in patients with nondialysis CKD

BACKGROUND & AIMS

Skeletal muscle mass measurements are important for customizing nutritional strategies for patients with chronic kidney disease (CKD). The serum creatinine-to-cystatin C ratio (Cr/CysC) is a potential indicator of sarcopenia. We developed simple equations to predict the appendicular skeletal muscle mass (ASM) of patients with CKD using readily available parameters and Cr/CysC.

METHODS

Overall, 573 patients with nondialysis CKD stages 3-5 were included for developing and validating the equations. The participants were randomly divided into development and validation groups in a 2:1 ratio. ASM was measured using the Body Composition Monitor (BCM), a multifrequency bioelectrical impedance spectroscopy device. The height, weight, anthropometric data, and handgrip strength (HGS) of the participants were obtained. Equations were generated using stepwise multiple linear regression models. The prognostic significance of the predicted ASM was evaluated in a CKD registry comprising 1043 patients.

RESULTS

The optimal equation without anthropometric data and HGS (Equation 1) was as follows: ASM (kg) = -7.949 - 0.049 × Age (years) - 2.213 × Woman + 0.090 × Height (cm) + 0.210 × Weight (kg) + 1.141 × Cr/CysC. The modified equation (Equation 2) with anthropometric data and HGS was as follows: ASM (kg) = -4.468 - 0.050 × Age (years) - 2.285 × Woman+ 0.079 × Height (cm) + 0.228 × Weight (kg) - 0.127 × Mid-arm muscular circumference (cm) + 1.127 × Cr/CysC. Both equations exhibited strong correlations with the ASM measured via BCM in the validation cohort (r = 0.944 and 0.943 for Equations 1 and 2, respectively) with minimal bias. When Equation 1 was applied to the CKD registry, the estimated ASM index (ASM/Height2) significantly predicted overall mortality over a median of 54 months.

CONCLUSIONS

Novel ASM equations offer a simple method for predicting skeletal muscle mass and can provide valuable prognostic information regarding patients with nondialysis CKD.

Exploring Renal Function Assessment: Creatinine, Cystatin C, and Estimated Glomerular Filtration Rate Focused on the European Kidney Function Consortium Equation

Serum creatinine and serum cystatin C are the most widely used renal biomarkers for calculating the estimated glomerular filtration rate (eGFR), which is used to estimate the severity of kidney damage. In this review, we present the basic characteristics of these biomarkers, their advantages and disadvantages, some basic history, and current laboratory measurement practices with state-of-the-art methodology. Their clinical utility is described in terms of normal reference intervals, graphically presented with age-dependent reference intervals, and their use in eGFR equations.

Renal dysfunction caused by severe hypothyroidism diagnosed by renal biopsy: a case report

There is a close relationship between thyroid dysfunction and renal dysfunction. However, thyroid dysfunction can unfortunately result in inaccurate measurements of serum creatinine and cystatin C levels. The chronic decrease in cardiac output due to hypothyroidism can reduce renal plasma flow (RPF) resulting in renal dysfunction. We report the case of a 36-year-old male in whom renal dysfunction detected during a company health check-up was found to be caused by severe hypothyroidism. His serum creatinine levels showed poor results, but serum cystatin C levels were within the normal range. The physician thus prioritized serum cystatin C for assessing the patient's renal function, and concluded that his renal function was normal. He subsequently visited our hospital, aged 36 years, for a comprehensive examination. His serum creatinine level was 1.88 mg/dL and his serum cystatin C level was 0.75 mg/dL, indicating an unusual discrepancy between the two measurements. The patient also presented with fatigue, suggesting hypothyroidism, and we therefore evaluated his thyroid function. His free thyroxine level was below the sensitivity of the assay, while his thyroid-stimulating hormone level was > 100 μIU/mL. A renal biopsy was performed to further explore the underlying cause of his renal dysfunction, which suggested that reduced RPF could be the leading cause of his renal ischemia, with no indications of chronic glomerulonephritis or other abnormalities. His hypothyroidism and renal function improved after thyroid hormone replacement therapy. Given the limited reports of renal biopsy tissue examination during the acute phase of hypothyroidism, the current case provides important information regarding the diagnosis of renal dysfunction in patients with hypothyroidism.

Correlation between serum markers and transjugular intrahepatic portosystemic shunt prognosis in patients with cirrhotic ascites

BACKGROUND

Individuals with refractory ascites in the context of liver cirrhosis typically face an adverse prognosis. The transjugular intrahepatic portosystemic shunt (TIPS) is an efficacious intervention, but there is a lack of reliable tools for postoperative prognosis assessment. Previously utilized clinical biochemical markers, such as the serum albumin concentration (Alb), sodium (Na+) concentration, and serum creatinine (Scr), have limited predictive value. Therefore, the quest for novel, specific biomarkers to evaluate the post-TIPS prognosis in patients with liver cirrhosis and refractory ascites holds significant practical importance.

AIM

To investigate the associations between the Child-Pugh score, model for end-stage liver disease (MELD) score, and serum cystatin C (Cys C) level and post-TIPS prognosis in patients with liver cirrhosis and refractory ascites.

METHODS

A retrospective analysis was conducted on 75 patients with liver cirrhosis and refractory ascites who underwent TIPS at our institution from August 2019 to August 2021. These patients were followed up regularly for two years, and the death toll was meticulously documented. The patients were allocated into a survival group (n = 45 patients) or a deceased group (n = 30 patients) based on their prognosis status. The clinical data of the two groups were collected, and Child-Pugh scores and MELD scores were calculated for analysis. Spearman correlation analysis was carried out to evaluate the correlation of prognosis with Child-Pugh grade, MELD score, and Cys C level. Additionally, a multiple-factor analysis utilizing the Cox proportional hazard model was used to identify independent risk factors affecting the post-TIPS prognosis of patients with liver cirrhosis and refractory ascites. The receiver operating characteristic curve (ROC) ascertained the predictive value of the Cys C concentration, Child-Pugh grade, and MELD score for the prognosis of liver cirrhosis with refractory ascites in post-TIPS patients.

RESULTS

During a 2-year follow-up period, among 75 patients with liver cirrhosis and refractory ascites who underwent TIPS treatment, 30 patients (40.00%) passed away. The deceased cohort exhibited heightened aspartate aminotransferase, alanine aminotransferase, total bilirubin, Scr, prothrombin time, Cys C, international normalized ratio, Child-Pugh, and MELD scores compared to those of the survival cohort, while Alb and Na+ levels were attenuated in the deceased group (P < 0.05). Spearman analysis revealed moderate to high positive correlations between prognosis and Child-Pugh score, MELD score, and Cys C level (r = 0.709, 0.749, 0.671, P < 0.05). Multivariate analysis using the Cox proportional hazard model demonstrated that the independent risk factors for post-TIPS prognosis in patients with liver cirrhosis and refractory ascites were Cys C (HR = 3.802; 95%CI: 1.313-11.015), Child-Pugh (HR = 3.030; 95%CI: 1.858-4.943), and MELD (HR = 1.222; 95%CI: 1.073-1.393) scores. ROC analysis confirmed that, compared to those of the classic prognostic models for Child-Pugh and MELD scores, the predictive accuracy of Cys C for post-TIPS prognosis in patients with liver cirrhosis and refractory ascites was slightly lower. This analysis yielded sensitivity and specificity values of 83.33% and 82.22%, respectively. The area under the curve value at this juncture was 0.883, with an optimal cutoff value set at 1.95 mg/L.

CONCLUSION

Monitoring the serum Cys C concentration is valuable for assessing the post-TIPS prognosis in patients with liver cirrhosis and refractory ascites. Predictive models based on serum Cys C levels, as opposed to Scr levels, are more beneficial for evaluating the condition and prognosis of patients with ascites due to cirrhosis.

Prognostic Value of Isolated High Serum Cystatin C Levels Without Glomerular Filtration Rate Reduction

OBJECTIVES

Cystatin C is increasingly used as a marker of renal function as a complement to serum creatinine and glomerular filtration rate (GFR). We have assessed its efficacy as a predictor of mortality in a group of patients with increased cystatin C but GFR> 60mL/min.

DESIGN AND METHODS

We included 608 patients, 65.9% male, 34.6% had diabetes mellitus. The mean age was 58.5±14.5 years and a mean GFR of 64.1±33.5mL/min. Patients were divided into 3 groups: CONTROL (normal cystatin C and GFR> 60mL/min, age 53.3±12.8years, GFR 96.6±22.4mL/min,n=193), INCREASED CYSTATIN (cystatin C>1.03mg/l and GFR>60mL/min, age 58.9±13,1years, GFR 72.2±10.4mL/min, n=40) and CKD (chronic kidney disease, increased cystatin C and GFR <60mL/min, age 61.4±14.8years, GFR 36.0±12.7mL/min, n=160). The relationship with overall mortality was analyzed using the Kaplan-Meier method.

RESULTS

Mean cystatin C was 0.75±0.13 versus 1.79±0.54 in CKD group and 1.14±0.14mg/l, p <0.001). In CONTROL group survival was 93.9% at 5y, compared to 78.8% in the ERC group and 82.3% in the INCREASED CYSTATIN group (p <0.001) Five-year survival before renal replacement therapy was also different for the ERC group (73%, p <0.001 Log Rank) but not between the other two groups (CONTROL 99.0%, INCREASED CYSTATIN 94.3% p=0.08).

CONCLUSIONS

Increased plasmatic levels of cystatin C in patients with GFR> 60mL/min was a predictor of increased mortality but not of progression to end-stage renal failure. These results confirm the interest of routinely measuring cystatin C.

Value of Cystatin C-Based Sarcopenia Index in Patients Undergoing Surgery for Renal Tumors

INTRODUCTION

Sarcopenia is a condition of low muscle strength and quantity, severe if low physical performances. The sarcopenia index (SI), calculated by blood levels of creatinine and cystatin C, had been reported to be correlated with skeletal muscle mass and is a potential simple screening tool for sarcopenia. We hypothesized that patients with a low SI, meaning low muscle mass, would have an inflated estimated glomerular filtration rate (eGFR) value based on serum creatinine levels. We also tested the prognostic value of the SI in a cohort of patients who had surgery for renal malignancies.

PATIENTS AND METHODS

We conducted a retrospective, observational study of 322 patients that had surgery for renal tumors in National Cancer Center Hospital East (Kashiwa, Chiba) between April 2017 and June 2023. We assessed sarcopenia measuring psoas muscle index (PMI), psoas muscle density (PMD), and skeletal muscle area (SMA) by computed tomography. We assessed the association between SI and eGFR before and after surgery. We also assessed the association between SI and postoperative outcome, including overall survival.

RESULTS

Of the 322 patients, 211 (66%) were males, with a median age of 69 years. SI had a weak correlation with both PMI and PMD in males (PMI: ρ = 0.25; PMD: ρ = 0.21). In females, SI and PMD exhibited a low correlation (ρ = 0.26), while SI and PMI displayed an insignificant correlation (ρ = 0.19). The correlation between SMA and SI was moderate for both males and females (males: ρ = 0.51; females: ρ = 0.46). After radical nephrectomy, eGFR decreased in 98% of patients with high SI, compared to 69% of patients with low SI. We also demonstrated that low SI predicted poor prognosis.

CONCLUSIONS

Clinicians can recognize the possibility of overestimated eGFR in the low SI group by measuring SI around the surgery. Low SI may also help predict poor prognosis.

Association of albuminuria with kidney function and hemodynamic disturbance in pre-school children who undergo congenital heart disease surgery

BACKGROUND

We validated the prevalence of albuminuria and its association with kidney function and hemodynamics in pre-school children who underwent surgery for congenital heart disease (CHD).

METHODS

From 403 patients who had undergone surgery for CHD at least 6 months before pre-school and were admitted to our hospital between 2011 and 2015, 75 who underwent blood and urine tests and cardiac catheterization were included in this study. The urinary albumin-to-creatinine ratio (ACR) was quantified, and the relationship of ACR with physical and laboratory findings and hemodynamics assessed using cardiac catheterization was analyzed.

RESULTS

The study cohort was divided into three groups: Fontan group (n = 25), tetralogy of Fallot (TOF) group (n = 18), and control group (other biventricular CHDs; n = 32). The median age of patients was 5.9 years. ACR was higher in the Fontan group than in the TOF and control groups (median: 15.0 vs. 5.0 and 0.0 mg/g, p < 0.001). Moreover, albuminuria (ACR > 30 mg/g) was observed in 20.0% of Fontan patients, while ACR was associated with potential complicating factors of Fontan circulation: high central venous pressure, high mean pulmonary artery pressure, and worse than moderate atrioventricular regurgitation. ACR showed a moderate correlation with the cystatin C-based estimated glomerular filtration rate (r =  - 0.725, p < 0.001).

CONCLUSIONS

Measurement of albuminuria in Fontan patients before they join elementary school is useful because it reflects kidney function and hemodynamic factors that can worsen their condition. Identification and management of patients with albuminuria may facilitate early therapeutic intervention for worsening Fontan factors, eventually delaying the deterioration of kidney function. A higher resolution version of the Graphical abstract is available as Supplementary information.

Estimated glomerular filtration rate among intensive care unit survivors: From the removal of race coefficient to cystatin C-based equations

PURPOSE

Black race coefficient used in serum creatinine (sCr)-based estimated glomerular filtration rate (eGFR) calculation may perpetuate racial disparities. Among intensive care unit (ICU) survivors, sCr overestimates kidney function due to sarcopenia. Cystatin C (cysC) is a race- and muscle mass-independent eGFR marker. We investigated the impact of removing the race coefficient from sCr-based eGFR and compared cysC- and sCr-based eGFR in ICU survivors.

MATERIALS AND METHODS

Among 30,920 patients from 2 institutions in the Bronx and Boston, eGFR was calculated at hospital discharge using sCr-based equations with and without race coefficient (eGFRsCr2009 and eGFRsCr2021). In a subset with available cysC between ICU admission and 1-year follow-up, sCr- and cysC-based estimates were compared.

RESULTS

eGFRsCr2021 was higher than eGFRsCr2009 by a median of 4 ml/min/1.73 m2 among non-Black patients and lower by a median of 8 ml/min/1.73 m2 among Black patients. Removing race coefficient reclassified 12.9% of non-Black subjects and 16.1% of Black subjects to better and worse eGFR category, respectively, and differentially impacted the prevalence of kidney dysfunction between the institutions due to differences in racial composition. Among 51 patients with available cysC (108 measurements), cysC-based estimates were lower than sCr-based estimates (median difference 9 to 16 ml/min/1.73 m2), resulting in reclassification to worse eGFR category in 34% to 53.5% of measurements.

CONCLUSIONS

Among ICU survivors, removal of race coefficient leads to lower eGFR in Black patients and may contribute to overestimation of kidney function in non-Black patients. While cysC is rarely used, estimates based on this marker are significantly lower than those based on sCr.

The relationship between serum creatinine/cystatin C ratio and mortality in hypertensive patients

BACKGROUND AND AIMS

Sarcopenia is a disease characterized by loss of skeletal muscle mass and function that is closely associated with cardiovascular disease. The serum creatinine/cystatin C (Cr/CysC) ratio has been shown to be a simplified indicator for identifying low muscle mass (LMM) or sarcopenia. The aim of this study was to investigate whether the Cr/CysC ratio helps to predict prognostic information in hypertensive patients.

METHODS AND RESULTS

This cohort study included 2509 patients with hypertension from the National Health and Nutrition Survey 1999-2002. To evaluate the association between Cr/CysC ratio and mortality, we used Kaplan Meier estimates to calculate cumulative survival probabilities for all-cause mortality and cardiovascular mortality, Cox regression analyses, and hazard ratio (HR) and 95% confidence interval (CI) were calculated. Over a median follow-up of 11.76 years, lower Cr/CysC ratio was associated with lower risk of all-cause mortality (per 0.1 increase, HR:0.81, 95% CI: 0.77-0.85, P < 0.001) and cardiovascular mortality (per 0.1 increase, HR:0.80, 95% CI: 0.72-0.89, P < 0.001). Compared with patients with normal muscle mass, all-cause mortality, and cardiovascular mortality HR for patients with LMM diagnosed by Cr/CysC ratio were 1.57 (95% CI: 1.36-1.82, P < 0.001) and 1.64 (95% CI: 1.12-2.42, P = 0.012), respectively.

CONCLUSION

We found that low muscle mass shown by lower Cr/CysC ratio was an independent risk factor for poor prognosis in hypertensive patients. We recommend routine screening of Cr/CysC ratio in hypertensive patients and early intervention for low muscle mass or sarcopenia.

Association of obstructive sleep apnea and diurnal variation of cystatin C

PURPOSE

Obstructive sleep apnea is a known risk factor for the progression of chronic kidney disease. To find early signs of the progression in subjects with obstructive sleep apnea., we assessed the diurnal variation of kidney biomarkers.

METHODS

A prospective observational study was conducted at Kangwon National University Hospital, Chuncheon, South Korea. All participants underwent in-laboratory polysomnography and phlebotomy in the evening before the polysomnography and in the morning after the polysomnography. Kidney biomarkers, including serum creatinine, blood urea nitrogen, and serum cystatin C, were measured. Delta kidney biomarkers were calculated by subtracting the evening level of the biomarkers from the morning level.

RESULTS

Twenty-six of 50 participants had severe obstructive sleep apnea. Delta cystatin C was significantly correlated with apnea-hypopnea index, oxygen desaturation index, and total arousal index with coefficients of -0.314, -0.323, and -0.289, respectively. In participants without severe obstructive sleep apnea, the morning cystatin C level (0.84 ± 0.11 mg/L) was significantly higher than the evening cystatin C level (0.81 ± 0.11 mg/L) (P = 0.005). With severe obstructive sleep apnea, the cystatin C levels were not different between the morning (0.85 ± 0.11 mg/L) and the evening (0.85 ± 0.10 mg/L).

CONCLUSIONS

Cystatin C level was increased in the morning in participants without severe obstructive sleep apnea, but not in participants with severe obstructive sleep apnea.

Longitudinal NGAL and cystatin C plasma profiles present a high level of heterogeneity in a mixed ICU population

BACKGROUND

NGAL and Cystatin C (CysC) as biomarkers for the early detection of AKI are subject to both pathophysiological, as well as patient related heterogeneity. The aim of this study was to investigate the timeline of plasma levels of NGAL and CysC during the first seven days of ICU admission in a mixed ICU population and to relate these to AKI severity during ICU stay. Via these means we aimed to bring clarity to the previously reported heterogeneity of these renal biomarkers.

METHODS

Prospective Observation Cohort. Consecutive patients admitted to adult ICU at an academic hospital in the Netherlands between 18-02-2014 and 31-03-2014 were included. Urine output, serum creatinine, plasma NGAL and CysC were recorded during the first seven days of ICU admission. Biomarker expression was analyzed based on KDIGO score and time of AKI diagnosis.

RESULTS

335 patients were included, 110 met KDIGO criteria for AKI. NGAL and CysC plasma levels were higher in AKI patients compared to non-AKI, high variability in individual values resulted in 56% of AKI patients having a false negative, and 32% of non-AKI patients having a false positive. Individual biomarker levels were variable, and no pattern based on KDIGO score was observed.

CONCLUSIONS

Plasma NGAL and CysC as biomarkers for the early AKI detection may be subject to pathophysiological, and patient related heterogeneity. Further understanding of individual biomarker profiles may help in their application amongst mixed ICU populations.

TRIAL REGISTRATION

The need for informed consent was waived by the Institutional Ethical Review Board of the University Medical Center Groningen (METc 2013 - 174) by Prof. dr. W.A. Kamps on May 17th 2013.

Serum cystatin C as a biomarker to predict all-cause mortality in geriatrics hip fracture

Background

Cystatin C, a low-molecular-weight protein, belongs to cysteine protease inhibitors produced primarily by nucleated cells. Its serum concentration, independent of sex, age, or muscle mass, is a good predictor of renal dysfunction in older adults. This study evaluated the association between all-cause mortality and preoperative cystatin C levels in hip fractures.

Materials and methods

Data describing the demographic and clinical characteristics of the patients were gathered specifically from older individuals who had suffered hip fractures. The study used linear and non-linear multivariate Cox regression models to investigate the association between preoperative cystatin C levels and mortality. The analyses were conducted using the R and EmpowerStats software.

Results

In total, two thousand three hundred and ninety-four patients were included in this study. A total of 790 patients (33 %) died of all causes. The mean follow-up was 37.62 months. The preoperative cystatin C was 0.91 ± 0.41 mg/L. Linear multivariate Cox regression analysis revealed a significant association between preoperative cystatin C level and death, with a hazard ratio (HR) of 2.19 (95 % confidence interval [CI]: 1.72-2.79, P < 0.0001). Nevertheless, the correlation between the variables was inconsistent. A cystatin C concentration of 1.62 mg/L marked a significant change in the non-linear relationship. A preoperative cystatin C level below 1.62 mg/L was found to be significantly linked with an increased risk of mortality (HR = 2.60, 95 % CI: 1.92-3.52, P < 0.0001). The mortality reached its highest point when the preoperative cystatin C level was greater than 1.62 mg/L. After that, the mortality risk did not increase further (HR = 1.54, 95 % CI: 0.98-2.42, P = 0.0588). The non-linear relationship remained consistent in the propensity score-matching sensitive analysis.

Conclusions

The study found a non-linear relationship between preoperative cystatin C levels and mortality in geriatric hip fractures. This suggests that preoperative cystatin C can be used as a predictor of the risk of death. The registration number is ChiCTR2200057323.

Subclinical atherosclerosis in patients with relapsing-remitting multiple sclerosis

BACKGROUND

Multiple sclerosis is an inflammatory disorder of the central nervous system. Inflammation may create high susceptibility to subclinical atherosclerosis. The purpose of this study was to compare subclinical atherosclerosis and the role of inflammatory cytokines between the group of patients with relapsing-remitting multiple sclerosis (RRMS) and healthy controls matched for age and sex.

METHODS

The study group consisted of 112 non-diabetic and non-hypertensive RRMS patients treated with disease modifying drugs (DMD) and the control group was composed of 51 healthy subjects. The common carotid artery (CCA) intima media thickness (IMT) was investigated. Serum levels of risk factors for atherosclerosis and inflammatory cytokines were also determined.

RESULTS

The mean CCA IMT (0.572 ± 0.131 mm vs. 0.571 ± 0.114 mm) did not differ (p > 0.05) between patients and controls. The RRMS patients' CCA IMT was significantly correlated with serum interleukin 6 (IL-6) (p = 0.027), high-sensitivity C-reactive protein (hs-CRP) (p = 0.027), cystatin C (p < 0.0005), glucose (p = 0.031), cholesterol (p = 0.008), LDL (p = 0.021), erythrocyte sedimentation rate (p = 0.001) and triglyceride (p = 0.018) level. We fitted generalized linear models in order to assess the relationship between CCA IMT and IL‑6 with adjustment for sex and age. The obtained results showed that adjusted for age (p < 0.001) and sex (p = 0.048) IL‑6 serum levels statistically significantly (p = 0.009) predict CCA IMT only in the RRMS group.

CONCLUSION

The findings of the present study suggest that when treated with DMD RRMS might not be an independent risk factor for early atherosclerosis presenting with arterial wall thickening; however, the results suggest a significant association of IL‑6 serum levels with CCA IMT only in the RRMS group.

Serum Cystatin C is a potential biomarker for predicting amyotrophic lateral sclerosis survival

OBJECTIVE

Currently, it is unclear whether serum Cystatin C can be used to evaluate the prognosis of ALS. We aim to study the relationship between serum Cystatin C and survival in ALS.

METHODS

Sporadic ALS patients diagnosed at the Department of Neurology, the First Medical Center, and the Chinese PLA General Hospital from January 2016 to December 2019 were enrolled in this study. Experienced neurologists followed up the participants regularly every 6 months until January 2022. According to the levels of serum Cystatin C, the participants were divided into high and low Cystatin C levels groups. The comparison between groups was performed with parametric or non-parametric test. Kaplan-Meier method and Cox regression model were used to calculate survival analysis.

RESULTS

Three hundred fifty-six sporadic ALS patients were enrolled in this study, including 203 males and 153 females. Among all ALS patients, 26 cases (7.3%) were lost to follow-up, 226 cases (63.5%) died, and 104 cases (29.2%) were still alive at the last follow-up. The median survival time of all ALS patients was 42.0 months. Patients with high Cystatin C levels had shorter median survival than those with lower Cystatin C levels (38.0 months vs. 48.0 months, P = 2.58 × 10-4). In multivariate Cox regression analysis, onset form, age of onset, diagnostic delay, disease progression rate, creatinine, and serum Cystatin C levels were associated with ALS survival.

CONCLUSIONS

Our study found that serum Cystatin C was associated with ALS survival, and serum Cystatin C level might be an independent predictor of ALS survival.

Prognostic value of the serum creatinine/cystatin C ratio in patients with chronic obstructive pulmonary disease

BACKGROUND

Sarcopenia, characterized by skeletal muscle atrophy and physical inactivity, is a manifestation of chronic obstructive pulmonary disease (COPD) and is associated with a poor prognosis. The serum creatinine (Cr)/cystatin C (CysC) ratio has been proposed as a marker of sarcopenia, given its correlation with total skeletal muscle mass, and as a prognostic indicator in COPD. This study aimed to evaluate the usefulness of the serum Cr/CysC ratio as a prognostic determinant in these patients.

METHODS

A total of 124 outpatients with COPD were enrolled in this study. Their serum Cr and CysC levels were measured. Survival time analyses were conducted to compare mortality rates between the low and high serum Cr/CysC ratio groups. Multivariate analysis was performed to investigate the association between various factors.

RESULTS

Using a serum Cr/CysC cut-off value of 0.885, the mortality rate (per 1000 person-years) for overall mortality was significantly higher in the low serum Cr/CysC ratio group (69.2 versus 28.6; hazard ratio, 2.47; 95% confidence interval, 1.06-5.79; p < 0.05). Similarly, the mortality rate due to respiratory disease was also higher (37.8 versus 8.2; hazard ratio, 4.68; 95% confidence interval, 1.05-20.9; p < 0.05). Multivariate Cox proportional hazards analysis revealed that serum Cr/CysC was an independent risk factor for respiratory disease mortality, regardless of age and airflow limitations.

CONCLUSIONS

The serum Cr/CysC ratio could be a valuable clinical parameter for identifying sarcopenia and severe airflow obstruction. The study findings highlight the utility of this ratio as a prognostic predictor in patients with COPD.

Kidney function predicts new-onset cardiorenal events and mortality in primary aldosteronism: approach of the 2021 race-free eGFR equation

Individuals with primary aldosteronism (PA) exhibit glomerular hyperfiltration, which may conceal underlying kidney damage. This observational cohort study enrolled 760 coronary artery disease-naive patients diagnosed with PA between January 1, 2007 and December 31, 2018 (male, 45%; mean age, 52.3 ± 11.9 years). The baseline estimated glomerular filtration rate (eGFR) was calculated using the 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, which includes serum creatinine and cystatin C but omits the race variable. During a mean follow-up of 5.8 ± 3.2 years, new-onset composite cardiovascular events (total death, non-fatal myocardial infarction, and coronary revascularization procedure) occurred at a crude incidence rate of 10.9 per 1,000 person-years. Multivariable Cox proportional hazards analysis showed that baseline eGFR was independently associated with composite cardiovascular events (hazard ratio [HR], 0.98 [95% CI, 0.97-0.99]). Penalized splines smoothing in multivariable regression analysis demonstrated that the risk of composite cardiovascular events increased negatively and linearly when patients had a baseline eGFR less than 85 mL/min/1.73 m2. Patients with baseline eGFR <85 mL/min/1.73 m2 were independently associated with higher risks of composite cardiovascular events (HR, 2.39 [95% CI, 1.16-4.93]), all-cause mortality (HR, 4.63 [95% CI, 1.59-13.46]), and adverse kidney events (sub-distribution HR, 5.96 [95% CI, 3.69-9.62], with mortality as a competing risk). Our data support baseline eGFR as a predictor for new-onset adverse cardiorenal events and emphasizes the importance of the early detection of kidney function impairment in hypertensive patients with PA. We also firstly validate the 2021 race-free CKD-EPI eGFR equation in Asian patents with PA. Even with the glomerular hyperfiltration phenomenon, baseline eGFR in patients with primary aldosteronism is associated with subsequent cardiorenal outcomes. The results also firstly point to the validity of the 2021 race-free CKD-EPI eGFR equation in healthcare and clinical decision-making.

Brief Report: Tyrosine Kinase Inhibitors for Lung Cancers That Inhibit MATE-1 Can Lead to "False" Decreases in Renal Function

INTRODUCTION

Select tyrosine kinase inhibitors (TKIs) used to treat oncogene-driven lung cancers also inhibit MATE-1. When MATE-1 is blocked, creatinine is retained in the serum. Elevated creatinine levels raise the specter of drug-induced intrarenal insufficiency despite the lack of true renal injury. We conducted a systematic analysis of MATE-1 inhibitor (MATEi)-treated patients to comprehensively characterize this phenomenon.

METHODS

Patients with oncogene-driven lung cancer treated with a wide variety of MATEi TKIs (brigatinib, cabozantinib, capmatinib, crizotinib, entrectinib, lorlatinib, pralsetinib, selpercatinib, and tepotinib) were eligible for an analysis of renal dysfunction. Acute kidney injury was classified on the basis of creatinine levels (Kidney Disease: Improving Global Outcomes criteria) as stage 1 (≥1.5× but <2× baseline), stage 2 (≥2× but <3× baseline), or stage 3 (>3× baseline). When available, cystatin C, a marker of kidney function unaffected by MATE-1, was used to evaluate the glomerular filtration rate (GFR).

RESULTS

We identified 863 patients receiving MATEi TKIs including crizotinib (39%, n = 333), lorlatinib (17%, n = 144), cabozantinib (10%, n = 87), selpercatinib (10%, n = 82), capmatinib (9%, n = 77), brigatinib (6%, n = 53), entrectinib (5%, n = 45), tepotinib (5%, n = 41), and pralsetinib (0.1%, n = 1). Of the 90 patients (10%) with acute kidney injury, Kidney Disease: Improving Global Outcomes stages 1, 2, and 3 were observed in 72% (n = 65), 21% (n = 19), and 7% (n = 6) of patients, respectively. Concurrently drawn creatinine and cystatin C levels on TKI therapy were available for 17 patients. In most cases (n = 15 of 17), the calculated GFR was higher using cystatin C versus creatinine. The percentage of patients whose GFR was higher using cystatin C versus creatinine by less than 10 mL/min, 10 to 19 mL/min, 20 to 29 mL/min, and more than or equal to 30 mL/min was 27% (n = four of 15), 20% (n = three of 15), 20% (n = three of 15), and 33% (n = five of 15), respectively. Long-term data in three patients that spanned 3 years revealed that GFR was higher using cystatin C versus creatinine in 96% (n = 49 of 51) of all time points. Using a virtual clinical trial GFR cutoff of 40 mL/min, the percentage of eligible patients rose from 41% (n = seven of 17) using creatinine calculations to 71% (n = 12 of 17) using cystatin C calculations.

CONCLUSIONS

The calculated GFR in patients with cancer receiving MATEi TKIs was higher in almost all cases when using cystatin C. When serum creatinine level seems elevated in patients receiving MATE-1 inhibitors, we recommend recalculating GFR using cystatin C before searching for other etiologies of kidney injury and reducing or stopping TKI therapy.

Incident Heart Failure Risk Reclassification With Race-Independent Estimated Glomerular Filtration Rate: A National Heart, Lung, and Blood Institute Pooled Cohorts Analysis

BACKGROUND

This study compared the predictive value of the race-independent creatinine- and cystatin C-based estimated glomerular filtration rate (eGFRcr-cys) and the race-dependent creatinine-based eGFR (eGFRcr) for incident heart failure (HF).

METHODS

This study combined the participant-level data from ARIC (Atherosclerosis Risk in Communities) (visit 4) and MESA (Multi-Ethnic Study of Atherosclerosis) (visit 1) to calculate eGFRcr-cys and eGFRcr. The primary outcome of the study was adjudicated incident HF over a follow-up period of 10 years. Multivariable Cox models were used to assess the risk of incident HF with the quartiles of eGFRcr-cys and eGFRcr.

RESULTS

Among 15,615 individuals (median age: 62 [57-68] years; 55.0% females; 23.9% Black), the median eGFRcr-cys and eGFRcr were 91.4 (79.4, 102.0) mL/min/1.73m2 and 84.7 (72.0, 94.7) mL/min/1.73m2, respectively. Compared with the fourth quartile of eGFRcr-cys, the hazard ratio for incident HF was 1.02 (95% CI:0.80-1.30) in the third quartile, 1.02 (95% CI:0.80-1.30) in the second quartile, and 1.47 (95% CI:1.16-1.86) in the first quartile. Compared with the 4th quartile of the eGFRcr, the risk of incident HF was similar in the 3rd (HRadj:0.90 [95% CI:0.73-1.12]), 2nd (HRadj: 0.96 [95% CI:0.77-1.20]), and 1st (HRadj:1.15 [95% CI:0.93-1.44]) quartiles. C-statistics were similar for the multivariable-adjusted Cox models for incident HF using eGFRcr (0.80 [0.79-0.81]) and eGFRcr-cys (0.80 [0.79-0.82]).

CONCLUSION

The eGFRcr and eGFRcr-cys had comparable predictive values for incident HF.

Differences in metabolic characteristics between Metabolically Healthy Obesity (MHO) and Metabolically Unhealthy Obesity (MUO) in weight reduction therapy

Metabolically Healthy Obesity (MHO) is generally recognized as the absence of any metabolic disorders and cardiovascular diseases, including type 2 diabetes, dyslipidemia, and hypertension, in obese individuals; however, it is not clearly defined. Therefore, the present study investigated differences in metabolic characteristics between individuals with MHO and Metabolically Unhealthy Obesity (MUO) during weight reduction therapy. The key factors defining MHO and the importance of weight reduction therapy for MHO were also examined. Cohort data from the Japan Obesity and Metabolic Syndrome (JOMS) study were analyzed. Subjects were divided into the MHO (n = 25) and MUO (n = 120) groups. Prior to weight reduction therapy, serum adiponectin levels were significantly higher in the MHO group than in the MUO group. Serum adiponectin levels also negatively correlated with the area of subcutaneous adipose tissue (SAT) and Homeostasis model assessment (HOMA)-R in the MHO group, but not in the MUO group. Collectively, the present results suggest the importance of adiponectin for maintaining metabolic homeostasis in the MHO group. On the other hand, no significant differences were observed in inflammatory markers between the MHO and MUO groups, suggesting the presence of chronic inflammation in both groups. Furthermore, a positive correlation was noted between changes in serum cystatin C levels and waist circumference in the MHO group, which indicated that despite the absence of metabolic disorders, the MHO group exhibited anti-inflammatory responses during weight reduction therapy. These results underscore the significance of weight reduction even for individuals with MHO.

Kidney Function Measures and Mortality: A Mendelian Randomization Study

RATIONALE & OBJECTIVE

Individuals with a low estimated glomerular filtration rate (eGFR) are at a high risk of death. However, the causes underpinning this association are largely uncertain. This study aimed to assess the causal relationship of low eGFR with all-cause and cause-specific mortality.

STUDY DESIGN

Retrospective cohort study incorporating Mendelian randomization (MR).

SETTING & PARTICIPANTS

Individual-level data from 436,214 White participants (54.3% female; aged 56.8±8.0 years) included in the UK Biobank.

EXPOSURES

eGFR estimated using cystatin C (eGFRcyst).

OUTCOMES

The outcomes of interest included all-cause mortality, cardiovascular mortality, cancer mortality, infection mortality, and other-cause mortality.

ANALYTICAL APPROACH

Cox proportional hazards analysis for the conventional observational analyses; linear and nonlinear MR analyses implemented using genetic allele scores as instrumental variables representing kidney function to estimate the effect of kidney function on the survival outcomes.

RESULTS

During a median follow-up of 12.1 years, there were 30,489 deaths, 6,098 of which were attributed to cardiovascular events, 15,538 to cancer, 1,516 to infection, and 7,227 to other events. In the conventional observational analysis, eGFRcyst exhibited a nonlinear association with all the outcomes. MR analysis suggested that a genetically predicted lower eGFRcyst was linearly associated with a higher rate of cardiovascular mortality (HR, 1.43; 95% CI, 1.18-1.75) across the entire measurement range (every 10-mL/min/1.73m2 decrement). Nonetheless, no causal associations between eGFRcyst and all-cause mortality (HR, 1.07; 95% CI, 0.98-1.17) or any types of noncardiovascular mortality were detected.

LIMITATIONS

Potential misclassification of the actual cause of death, a nonrepresentative sample, and potential error in the interpretation of the magnitude of associations generated in MR analyses.

CONCLUSIONS

These findings suggest a potential causal association between low eGFR and cardiovascular mortality in the general population, but no causal relationship with all-cause mortality or noncardiovascular mortality was observed. Further studies in other populations are warranted to confirm these findings.

PLAIN-LANGUAGE SUMMARY

This study investigated the existence of a causal relationship between lower kidney function and death of different causes. Using data from 436,214 people in the United Kingdom, we applied conventional statistical analyses and those incorporating genetic data to implement Mendelian randomization, an approach that estimates causal associations. The observational analysis showed a nonlinear association between kidney function and various types of mortality outcomes. However, Mendelian randomization analysis suggested a linear increase in the risk of cardiovascular mortality with lower kidney function, but no causal link between the level of kidney function and all-cause or noncardiovascular mortality was identified. Managing kidney health may help reduce cardiovascular mortality, but caution is needed in interpreting the magnitudes of these results. Further validation in other populations and in those with advanced kidney failure is needed.

Cystatin C as a GFR Estimation Marker in Acute and Chronic Illness: A Systematic Review

Rationale & Objective

Creatinine-based GFR estimating (eGFRcr) equations may be inaccurate in populations with acute or chronic illness. The accuracy of GFR equations that use cystatin C (eGFRcys) or creatinine-cystatin C (eGFRcr-cys) is not well studied in these populations.

Study Design

A systematic review of original articles identified from PubMed and expert sources. Two reviewers screened articles independently and identified those meeting inclusion criteria.

Setting & Study Populations

Adults and children with acute or chronic illness.

Selection Criteria for Studies

Studies published since 2011 that compared performance of eGFRcr, eGFRcys, and eGFRcr-cys relative to measured GFR (mGFR), used standardized assays for creatinine or cystatin C, and used eGFR equations developed using such assays. Studies of ambulatory clinical populations or research studies in populations with only CKD, kidney transplant recipients, only diabetes, kidney donor candidates, and community-based cohorts were excluded.

Data Extraction

Data extracted from full text.

Analytical Approach

Bias and percentages of estimates within 30% of mGFR (P30) of eGFR compared with mGFR were evaluated.

Results

Of the 179 citations, 26 studies met the inclusion criteria: 24 in adults and 2 in children in clinical populations with cancer (n=5), HIV (n=5), cirrhosis (n=3), liver transplant (n=3), heart failure (n=2), neuromuscular diseases (n=1) critical illness (n=5), and obesity (n=2). In general, eGFRcr-cys had greater accuracy than eGFRcr or eGFRcys equations among study populations with cancer, HIV, and obesity, but did not perform consistently better in cirrhosis, liver transplant, heart failure, neuromuscular disease, and critical illness.

Limitations

Participants were selected because of concern for inaccurate eGFRcr, which may bias results. Most studies had small sample sizes, limiting generalizability.

Conclusions

eGFRcr-cys improves GFR estimation in populations with a variety of acute and chronic illnesses, providing indications for cystatin C measurement. Performance was poor in many studies, suggesting the need for more frequent mGFR.

Plain-Language Summary

Kidney function, specifically glomerular filtration rate (GFR), estimated using creatinine (eGFRcr) is often inaccurate in people with acute and chronic illness. The accuracy of estimates using cystatin C alone (eGFRcys) or together with creatinine (eGFRcr-cys) is not well studied in these populations. We conducted a systematic review to address the knowledge gap. Of the 179 papers reviewed, we identified 26 studies in clinical populations with cancer (n=5); HIV (n=5); cirrhosis (n=3); liver transplant (n=3); heart failure (n=2); neuromuscular disease (n=1); critical illness (n=5); and obesity (n=2). In general, eGFRcr-cys improved the GFR estimation in HIV, cancer, and obesity, providing indications for cystatin C measurement. Performance was poor in many studies, suggesting the need for more frequent measured GFR.

Application of GFR estimating equations to children with normal, near-normal, or discordant GFR

BACKGROUND

The objective was to determine the extent that eGFR formulas correspond to measured plasma iohexol clearance (iGFR) in children with normal or near normal kidney function, particularly how different eGFR formulas yield discordant results.

METHODS

iGFR from 2 (iGFR-2pt) and 4 (iGFR-4pt) time points along with creatinine and/or cystatin C-based eGFR were measured in children with mild CKD, stages 1-2. eGFR was calculated using 6 equations: 3 under 25 (U25) formulas from the Chronic Kidney Disease in Children (CKiD) study, the full age-combined cystatin C (cysC) and creatinine spectrum (FAS-combined), the European Kidney Function Consortium (EKFC-creatinine) equation, and the Chronic Kidney Disease Epidemiology Collaboration (CKD-epi) cysC-based equation.

RESULTS

Twenty-nine children were included, of which 22 had discordant creatinine vs. cystatin C-based eGFR by ≥ 15mL/min/1.73 m2. Overall, the FAS-combined had the least bias, while the U25 most accurately identified children with an eGFR < 90 mL/min/1.73 m2. When Cr-eGFR was ≥ 15 mL/min higher than CysC-eGFR, the U25 creatinine eGFR was closest to iGFR-4pt. When CysC eGFR was higher, the U25-combined was closest to iGFR-4pt.

CONCLUSION

The formulas that most closely approximated the measured GFR varied depending on the pattern of discordant eGFR results. Based on the results, we recommend using the CKiD U25-combined formula to screen for children with a low GFR. Either the CKiD U25-combined or FAS-combined would be recommended for changes in eGFR longitudinally. However, because all formulas were discordant from the iGFR-4pt in over a third of participants, further refinement of pediatric eGFR formulas is needed at the normal/near-normal range. A higher resolution version of the Graphical abstract is available as Supplementary information.

Serum cystatin C predicts the risk of non-ST-elevation acute coronary syndrome

OBJECTIVE

Inflammation markers have been proposed as the predictors of adverse cardiac events in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS). This study aimed to investigate prognostic value of serum cystatin C (Cys-C) for NSTE-ACS patients.

METHODS

Cys-C, neutrophil to lymphocyte ratio (NLR) and high-sensitivity C-reactive protein (hsCRP) were examined in 212 NSTE-ACS patients and 60 controls. Global registry of acute coronary events (GRACE) score and major adverse cardiac events (MACE) in NSTE-ACS patients were recorded.

RESULTS

Cys-C level in the serum was significantly higher in NSTE-ACS patients than in control, and was positively correlated with hsCRP level and NLR as well as GRACE score at admission and 6 months after discharge in NSTE-ACS patients. Serum Cys-C level was identified as a new predictor of MACE.

CONCLUSION

Serum Cys-C level may be an inflammation biomarker in patients with NSTE-ACS, and could be used as an independent predictor of MACE.

Effect of stress hyperglycaemia on acute kidney injury in non-diabetic critically ill patients?

BACKGROUND

Stress hyperglycaemia (SH) and acute kidney injury (AKI) occur frequently in critically ill patients, and particularly non-diabetics are associated with adverse outcome. Data is scarce on the effect of SH on AKI. We assessed whether SH (i) preceded AKI, (ii) was a risk factor of subsequent AKI, and (iii) how SH and tubular injury interacted in AKI development in critically ill, non-diabetics.

METHODS

Case-control study of 82 patients each with and without SH matched by propensity score for multiple demographic characteristics. AKI was defined by KDIGO criteria, SH either as blood glucose (BG) > 140 mg/dl (BG140), > 200 mg/dl (BG200), or stress hyperglycemia rate (SHR) ≥ 1.47 (SHR1.47) as measured 2 days before AKI. Urinary cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) indicated tubular injury.

RESULTS

In AKI, SH rates were frequent using all 3 definitions applied, but highest when BG140 was applied. SH by all 3 definitions was consistently associated with AKI. This was independent of established risk factors of AKI such as sepsis and shock. Increments of BG, urinary NGAL or cystatin C, and its products, were independently associated with the likelihood of subsequent AKI, demonstrating their reciprocal potentiating effects on AKI development.

CONCLUSIONS

SH is frequent in critically ill, non-diabetics with AKI. SH was identified as an independent risk factor of AKI. Higher BG combined with tubular injury may potentiate their adverse effects on AKI.

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.

Serum Cystatin C within 24 hours after admission: a potential predictor for acute kidney injury in Chinese patients with community acquired pneumonia

BACKGROUND

Acute kidney injury (AKI) is common in patients with community-acquired pneumonia (CAP), and is associated with poor prognosis. Therefore, in this study, we evaluated whether AKI in Chinese patients with CAP could be well predicted by serum Cystatin C within 24 h after admission.

METHODS

Univariate and multivariate logistic regression analyses were used to investigate independent factors of AKI in patients with CAP.

RESULTS

Totally, 2716 patients with CAP were included in this study. 766 (28%) patients developed AKI. After multivariate logistic regression analysis, serum Cystatin C (odds ratio [OR] 4.27, 95% confidence interval [CI] 3.36-5.44; p < 0.001) was an independent factor for AKI in patients with CAP. Serum Cystatin C had an area under the receiver operating characteristic curve (AUC) of 0.81 for predicting AKI, with an optimal cutoff value of 1.37 mg/L, computing 68% sensitivity, 80% specificity. Furthermore, serum Cystatin C within 24 h after admission still had a good and stable prediction efficiency for AKI in various subgroups (age, gender, hypertension, diabetes, coronary artery disease, cardiac insufficiency, cerebrovascular disease, atrial fibrillation, chronic obstructive pulmonary disease, chronic kidney disease, and tumor, albumin, anemia, platelet count, white blood cell count, and uric acid, confusion, uremia, respiratory rate, blood pressure, and age 65 years or older [CURB-65] score, acute respiratory failure, intensive care unit admission, and mechanical ventilation) of patients with CAP (AUCs: 0.69-0.84).

CONCLUSION

Serum Cystatin C within 24 h after admission appears to be a good biomarker for predicting AKI in Chinese patients with CAP.

Associations between ultra-processed food consumption and kidney function in an older adult population with metabolic syndrome

BACKGROUND & AIMS

Ultra-processed food (UPF) consumption has increased dramatically over the last decades worldwide. Although it has been linked to some cardiometabolic comorbidities, there is limited evidence regarding kidney function. This study aimed to cross-sectionally and longitudinally assess the association between UPF consumption and estimated-glomerular filtration rate (eGFR) based on Cystatin C (CysC).

METHODS

Older adults (mean age 65 ± 5.0 years, 46% women) with overweight/obesity and metabolic syndrome (MetS) who had available data of CysC at baseline (n = 1909), at one-year and at 3-years of follow-up (n = 1700) were analyzed. Food consumption was assessed using a validated 143-item semi-quantitative food frequency questionnaire and UPF consumption (% of g/d) at baseline and changes after one-year of follow-up were estimated according to NOVA classification system. Multivariable-adjusted linear and logistic regression models were performed to evaluate the cross-sectional associations between UPF consumption with eGFR levels and decreased kidney function (eGFR <60 ml/min/1.73 m2) at baseline. Multivariable-adjusted mixed-effects linear regression models were fitted to investigate the associations between one-year changes in UPF and eGFR over 3-years of follow-up.

RESULTS

Individuals with the highest baseline UPF consumption showed lower eGFR (β: -3.39 ml/min/1.73 m2; 95% CI: -5.59 to -1.20) and higher odds of decreased kidney function (OR: 1.64; 95% CI: 1.21 to 2.22) at baseline, compared to individuals in the lowest tertile. Participants in the highest tertile of one-year changes in UPF consumption presented a significant decrease in eGFR after one-year of follow-up (β: -1.45 ml/min/1.73 m2; 95% CI: -2.90 to -0.01) as well as after 3-years of follow-up (β: -2.18 ml/min/1.73 m2; 95% CI: -3.71 to -0.65) compared to those in the reference category.

CONCLUSIONS

In a Mediterranean population of older adults with overweight/obesity and MetS, higher UPF consumption at baseline and one-year changes towards higher consumption of UPF were associated with worse kidney function at baseline and over 3-years of follow-up, respectively.

CLINICAL TRIAL REGISTRY NUMBER

ISRCTN89898870.

Serum cystatin C is correlated with mortality of traumatic brain injury patients partially mediated by acute kidney injury

BACKGROUND

Evaluating risk of poor outcome for Traumatic Brain Injury (TBI) in early stage is necessary to make treatment strategies and decide the need for intensive care. This study is designed to verify the prognostic value of serum cystatin C in TBI patients.

METHODS

415 TBI patients admitted to West China hospital were included. Logistic regression was performed to explore risk factors of mortality and testify the correlation between cystatin C and mortality. Mediation analysis was conducted to test whether Acute Kidney Injury (AKI) and brain injury severity mediate the relationship between cystatin C level and mortality. Area under the receiver operating characteristic curve (AUC) was used to evaluate the prognostic value of cystatin C and the constructed model incorporating cystatin C.

RESULTS

The mortality rate of 415 TBI patients was 48.9%. Non-survivors had lower GCS (5 vs 8, p < 0.001) and higher cystatin C (0.92 vs 0.71, p < 0.001) than survivors. After adjusting confounding effects, multivariate logistic regression indicated GCS (p < 0.001), glucose (p < 0.001), albumin (p = 0.009), cystatin C (p < 0.001) and subdural hematoma (p = 0.042) were independent risk factors of mortality. Mediation analysis showed both AKI and brain injury severity exerted mediating effects on relationship between cystatin C and mortality of included TBI patients. The AUC of combining GCS with cystatin C was 0.862, which was higher than that of GCS alone (Z = 1.7354, p < 0.05).

CONCLUSION

Both AKI and brain injury severity are mediating variables influencing the relationship between cystatin C and mortality of TBI patients. Serum cystatin C is an effective prognostic marker for TBI patients.

Cystatin C-derived estimated glomerular filtration rate in children with sickle cell anaemia

BACKGROUND

Sickle cell disease is the most common inherited blood disorder in humans and constitutes a major public health burden. It is a multisystemic condition with long-term renal complications. Early detection of sickle cell nephropathy and initiation of appropriate interventions are associated with improved survival and quality of life. This study aimed to compare the cystatin C-derived estimated glomerular filtration rate (GFR) of the study groups and also, to correlate the clinical features of chronic kidney disease (CKD) with decreased GFR in children with sickle cell anaemia (SCA).

METHODS

This hospital-based cross-sectional analytic study recruited 86 SCA subjects in steady-state and 86 age and sex-matched healthy HbAA controls aged 1-14 years who attended the Paediatric Haematology and Outpatient clinics of Federal Medical Centre Bida over six months. Data were collected using a semi-structured questionnaire, and participants' length/height, weight, and blood pressure were measured using standard procedures. Blood samples were drawn for serum cystatin C assay via the sandwich enzyme-linked immunosorbent assay (ELISA) technique. Filler's equation was used to calculate the glomerular filtration rate.

RESULTS

There was a significant difference in the mean cystatin C-derived GFR between the two groups, i.e. 116 ± 30mL/min/1.73m2 vs. 106 ± 24mL/min/1.73m2 for the SCA and control groups, respectively (p = 0.017). The prevalence of supernormal GFR (i.e. GFR > 140mL/min/1.73m2) and decreased GFR (i.e. GFR < 90mL/min/1.73m2) was 19.8% and 22.1%, respectively, in children with SCA. There was no significant association between the age at diagnosis of SCA, blood transfusions, blood pressure, packed cell volume and presence of peripheral oedema with decreased GFR in the study subjects.

CONCLUSIONS

Supernormal GFR is common in children with SCA and there is no significant association between clinical features of CKD with decreased GFR. Regular evaluation of renal function is, however, recommended in children with SCA for early detection and treatment of renal complications in order to halt the progression to end-stage kidney disease (ESKD).

The Difference Between Cystatin C- and Creatinine-Based Estimated GFR in Heart Failure With Reduced Ejection Fraction: Insights From PARADIGM-HF

RATIONALE & OBJECTIVE

The clinical implications of the discrepancy between cystatin C (cysC)- and serum creatinine (Scr)-estimated glomerular filtration rate (eGFR) in patients with heart failure (HF) and reduced ejection fraction (HFrEF) are unknown.

STUDY DESIGN

Post-hoc analysis of randomized trial data.

SETTING & PARTICIPANTS

1,970 patients with HFrEF enrolled in PARADIGM-HF with available baseline cysC and Scr measurements.

EXPOSURE

Intraindividual differences between eGFR based on cysC (eGFRcysC) and Scr (eGFRScr; eGFRdiffcysC-Scr).

OUTCOMES

Clinical outcomes included the PARADIGM-HF primary end point (composite of cardiovascular [CV] mortality or HF hospitalization), CV mortality, all-cause mortality, and worsening kidney function. We also examined poor health-related quality of life (HRQoL), frailty, and worsening HF (WHF), defined as HF hospitalization, emergency department visit, or outpatient intensification of therapy between baseline and 8-month follow-up.

ANALYTICAL APPROACH

Fine-Gray subdistribution hazard models and Cox proportional hazards models were used to regress clinical outcomes on baseline eGFRdiffcysC-Scr. Logistic regression was used to investigate the association of baseline eGFRdiffcysC-Scr with poor HRQoL and frailty. Linear regression models were used to assess the association of WHF with eGFRcysC, eGFRScr, and eGFRdiffcysC-Scr at 8-month follow-up.

RESULTS

Baseline eGFRdiffcysC-Scr was higher than +10 and lower than-10mL/min/1.73m2 in 13.0% and 35.7% of patients, respectively. More negative values of eGFRdiffcysC-Scr were associated with worse outcomes ([sub]hazard ratio per standard deviation: PARADIGM-HF primary end point, 1.18; P=0.008; CV mortality, 1.34; P=0.001; all-cause mortality, 1.39; P<0.001; worsening kidney function, 1.31; P=0.05). For a 1-standard-deviation decrease in eGFRdiffcysC-Scr, the prevalences of poor HRQoL and frailty increased by 29% and 17%, respectively (P≤0.008). WHF was associated with a more pronounced decrease in eGFRcysC than in eGFRScr, resulting in a change in 8-month eGFRdiffcysC-Scr of-4.67mL/min/1.73m2 (P<0.001).

LIMITATIONS

Lack of gold-standard assessment of kidney function.

CONCLUSIONS

In patients with HFrEF, discrepancies between eGFRcysC and eGFRScr are common and are associated with clinical outcomes, HRQoL, and frailty. The decline in kidney function associated with WHF is more marked when assessed with eGFRcysC than with eGFRScr.

PLAIN-LANGUAGE SUMMARY

Kidney function assessment traditionally relies on serum creatinine (Scr) to establish an estimated glomerular filtration rate (eGFR). However, this has been challenged with the introduction of an alternative marker, cystatin C (cysC). Muscle mass and nutritional status have differential effects on eGFR based on cysC (eGFRcysC) and Scr (eGFRScr). Among ambulatory patients with heart failure enrolled in PARADIGM-HF, we investigated the clinical significance of the difference between eGFRcysC and eGFRScr. More negative values (ie, eGFRScr>eGFRcysC) were associated with worse clinical outcomes (including mortality), poor quality of life, and frailty. In patients with progressive heart failure, which is characterized by muscle loss and poor nutritional status, the decline in kidney function was more pronounced when eGFR was estimated using cysC rather than Scr.

Serum cystatin C for risk stratification of prediabetes and diabetes populations

BACKGROUND

The association between serum cystatin C level and vascular outcomes has not been fully elucidated in diabetes and is unclear in prediabetes. We aim to evaluate whether cystatin C level predicts future risk for mortality and vascular outcomes in prediabetes and diabetes.

METHODS

A total of 85,371 participants with prediabetes and diabetes, and available baseline cystatin C in the UK biobank were included with a 14-year follow-up. Cox hazards models were used to calculate the associations between cystatin C level, mortality (all-cause, cause-specfic mortality) and vascular outcomes (myocardial infarction [MI], stroke, end-stage renal disease [ESRD] and diabetic retinopathy [DR]). The 1136 diabetes subjects in Guangzhou Diabetic Eye Study (GDES) were included for examing the impact of cystatin C on in vivo retinal degeneration and microvascular changes by using SS-OCT and OCTA.

RESULTS

The highest cystatin C quartile had increased risks of all-cause (hazard ratio [HR], 2.02; 95% confidence interval [CI] 1.86-2.19), cardiovascular (HR, 2.29; 95% CI 1.97-2.67), cancer (HR, 1.86; 95% CI 1.65-2.10) and other-cause mortality (HR, 2.24; 95% CI 1.90-2.64), MI (HR, 1.40; 95% CI 1.26-1.55), stroke (HR, 1.88; 95% CI, 1.57-2.26), ESRD (HR, 7.33; 95% CI, 5.02-10.71), DR (HR, 1.17; 95% CI 1.03-1.32) than those in the lowest quartile. Adding cystatin C to the conventional model improved C-statistic for all-cause (0.699-0.724), cardiovascular (0.762-0.789), cancer (0.661-0.674) and other-cause mortality (0.675-0.715), MI (0.748-0.750), stroke (0.712-0.718), and ESRD (0.808-0.827). The GDES analysis identified a strong association between increased cystatin C levels and diminished retinal neural layers, as well as microvascular rarefaction in both macular and optic disc regions (all P < 0.05).

CONCLUSIONS

Serum cystatin C refines the risk stratification for mortality and vascular outcomes among patients with prediabetes or diabetes.

Effect of Two Cystatin C Reagents and Four Equations on Glomerular Filtration Rate Estimations After Standardization

Background

Serum cystatin C (cysC), which is less affected by sex, race, and muscle mass than creatinine, is a useful biomarker of the estimated glomerular filtration rate (eGFR). The standardization of cysC measurements remains controversial, although a certified reference material (ERM-DA471/IFCC) is available. Moreover, the effect of combinations of cysC reagents and equations for eGFR is unclear.

Methods

We conducted a simulation analysis of cysC measured using two reagents standardized against ERM-DA471/IFCC-Gentian cystatin C immunoassay (Gentian_cys; GentianAS, Moss, Norway) and Roche Tina-quant Cystatin C Gen.2 (Roche_cys; Roche, Mannheim, Germany)-on a Cobas c702 system (Roche) and eGFR generated by eight combinations of four equations: 2012 cystatin C-based Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI_cys); the Caucasian, Asian, pediatric, and adult equation (CAPA_eq); full age spectrum equation (FAS_eq); and 2023 cystatin C-based European Kidney Function Consortium equation (EKFC_cys).

Results

A total of 148 participants (mean age, 60.5±14.5 years; 43% female) were enrolled. The mean cysC was 1.72±1.44 mg/L for Gentian_cys and 1.71±1.35 mg/L for Roche_cys. Regression analysis showed concordance between the reagents within 0.85-4.40 mg/L when using ±7.61% total allowable error. Lin's concordance correlation coefficient of eGFR, by combining the measuring system and equation, varied from 0.73 to 1.00.

Conclusions

The equivalence of cysC values at low concentrations (<0.85 mg/L) between the two reagents was unsatisfactory. Results obtained with different measurement systems could lead to larger differences in eGFR varying with the combination.

Comparison of cardiovascular event predictability between the 2009 and 2021 Chronic Kidney Disease Epidemiology Collaboration equations in a Korean chronic kidney disease cohort: the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease

BACKGROUND

The 2009 Chronic Kidney Disease Epidemiology Collaboration creatinine-based estimated glomerular filtration rate (eGFRcr) equation contains a race component that is not based on biology and may cause a bias in results. Therefore, the 2021 eGFRcr and creatinine-cystatin C-based eGFR (eGFRcr-cysC) equations were developed with no consideration of race. This study compared the cardiovascular event (CVE) and all-cause mortality and CVE combined predictability among the three eGFR equations in Korean chronic kidney disease (CKD) patients.

METHODS

This study included 2,207 patients from the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease. Receiver operating characteristic (ROC) and net reclassification improvement (NRI) index were used to compare the predictability of the study outcomes according to the 2009 eGFRcr, 2021 eGFRcr, and 2021 eGFRcr-cysC equations.

RESULTS

The overall prevalence of CVE and all-cause mortality were 9% and 7%, respectively. There was no difference in area under the curve of ROC for CVE and mortality and CVE combined among all three equations. Compared to the 2009 eGFRcr, both the 2021 eGFRcr (NRI, 0.013; 95% confidence interval [CI], - 0.002 to 0.028) and the eGFRcr-cysC (NRI, -0.001; 95% CI, -0.031 to 0.029) equations did not show improved CVE predictability. Similar findings were observed for mortality and CVE combined predictability with both the 2021 eGFRcr (NRI, -0.019; 95% CI, -0.039-0.000) and the eGFRcr-cysC (NRI, -0.002; 95% CI, -0.023 to 0.018).

CONCLUSION

The 2009 eGFRcr equation was not inferior to either the 2021 eGFRcr or eGFRcr-cysC equation in predicting CVE and the composite of mortality and CVE in Korean CKD patients.