Serum cystatin C and left ventricular diastolic dysfunction in children with chronic kidney disease

Hemodializ Hastalarında Sistatin C Düzeyleri, Oksidan-Antioksidan ve İnflamasyon Durumu

Objective: Cystatin C is considered an important marker for the detection of renal dysfunction. It was aimed to determine cystatin C levels, status of oxidant-antioxidant and inflammation in hemodialysis (HD) patients. Methods: The study groups consisted of 20 HD patients and 20 healthy controls. Blood samples were obtained from the control group and from the HD group before hemodialysis. Serum cystatin C, total antioxidant capacity (TAC), total oxidative state (TOS), tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6) interleukin 18 (IL-18) levels were detected by Enzyme Linked Immunosorbent Assay (ELISA), C-reactive protein (CRP) and some biochemical parameters were analyzed by autoanalyser. Results: Cystatin C, TOS, TNF-α, IL-6, IL-18 and CRP levels of the HD group were significantly higher than the control group. Conclusion: As a result; oxidative stress and inflammation were increased in patients with chronic renal failure undergoing hemodialysis. New strategies and new studies are needed to reduce the increase in oxidative stress and inflammation in HD patients.

Impaired Systolic and Diastolic Left Ventricular Function in Children with Chronic Kidney Disease - Results from the 4C Study

Children with chronic kidney disease suffer from excessive cardiovascular mortality and early alterations of the cardiovascular system. Tissue doppler imaging is a validated echocardiographic tool to assess early systolic and diastolic cardiac dysfunction. We hypothesized that tissue Doppler velocities would reveal reduced cardiac function in children with chronic kidney disease compared to healthy children. A standardized echocardiographic exam was performed in 128 patients of the Cardiovascular Comorbidity in Children with Chronic Kidney Disease (4C) Study aged 6–17 years with an estimated glomerular filtration rate (eGFR) below 60 ml/min/1.73 m². Tissue Doppler measurements included early (E’) and late (A’) diastolic and systolic (S’) velocity at the mitral and septal annulus of the left ventricle. Measured values were normalized to z-scores using published reference data. Predictors of E’/A’, E/E’, S’ and left ventricular mass index (LVMI) were assessed by multiple linear regression analyses. Tissue Doppler E’ was reduced and tissue Doppler A’ increased, resulting in a reduced tissue Doppler E’/A’ ratio (z-score −0.14, p < 0.0001) indicating reduced diastolic function compared to healthy children. Reduced tissue Doppler E’/A’ Z-Scores were independently associated with lower eGFR (p = 0.002) and increased systolic blood pressure (p = 0.02). While E/E’ Z-Scores were increased (Z-score 0.57, p < 0.0001), patients treated with pharmacological RAS blockade but not with other antihypertensive treatments had significantly lower E/E’ and higher E’/A’ Z-Scores. Systolic tissue Doppler velocities were significantly decreased (Z-score −0.24, p = 0.001) and inversely correlated with E/E’ Z-Scores (r = −0.41, p < 0.0001). LVMI was not associated with systolic or diastolic tissue Doppler velocities. Concentric left ventricular hypertrophy showed a tendency to lower S’ in multivariate analysis (p = 0.13) but no association to diastolic function. Concentric left ventricular geometry was significantly associated with lower midwall fractional shortening. In summary, systolic and diastolic function assessed by tissue Doppler is impaired. eGFR, systolic blood pressure and the type of antihypertensive medications are significant predictors of diastolic function in children with CKD. Left ventricular morphology is largely independent of tissue Doppler velocities. Tissue Doppler velocities provide sensitive information about early left ventricular dysfunction in this population.

The association between creatinine versus cystatin C-based eGFR and cardiovascular risk in children with chronic kidney disease using a modified PDAY risk score

BACKGROUND

Children with chronic kidney disease (CKD) have a high prevalence of cardiovascular disease (CVD) risk factors which may contribute to the development of cardiovascular events in adulthood. Among adults with CKD, cystatin C-based estimates of glomerular filtration rate (eGFR) demonstrate a stronger predictive value for cardiovascular events than creatinine-based eGFR. The PDAY (Pathobiological Determinants of Atherosclerosis in Youth) risk score is a validated tool used to estimate the probability of advanced coronary atherosclerotic lesions in young adults.

OBJECTIVE

To assess the association between cystatin C-based versus creatinine-based eGFR (eGFR cystatin C and eGFR creatinine, respectively) and cardiovascular risk using a modified PDAY risk score as a proxy for CVD in children and young adults.

METHODS

We performed a cross-sectional study of 71 participants with CKD [median age 15.5 years; inter-quartile range (IQR) 13, 17], and 33 healthy controls (median age 15.1 years; IQR 13, 17). eGFR was calculated using age-appropriate creatinine- and cystatin C-based formulas. Median eGFR creatinine and eGFR cystatin C for CKD participants were 50 (IQR 30, 75) and 53 (32, 74) mL/min/1.73 m², respectively. For the healthy controls, median eGFR creatinine and eGFR cystatin were 112 (IQR 85, 128) and 106 mL/min/1.73m² (95, 123) mL/min/1.73 m², respectively. A modified PDAY risk score was calculated based on sex, age, serum lipoprotein concentrations, obesity, smoking status, hypertension, and hyperglycemia.

RESULTS

Modified PDAY scores ranged from -2 to 20. The Spearman's correlations of eGFR creatinine and eGFR cystatin C with coronary artery PDAY scores were -0.23 (p = 0.02) and -0.28 (p = 0.004), respectively. Ordinal logistic regression also showed a similar association of higher eGFR creatinine and higher eGFR cystatin C with lower PDAY scores. When stratified by age <18 or ≥18 years, the correlations of eGFR creatinine and eGFR cystatin C with PDAY score were modest and similar in children [-0.29 (p = 0.008) vs. -0.32 (p = 0.004), respectively]. Despite a smaller sample size, the correlation in adults was stronger for eGFR cystatin C (-0.57; p = 0.006) than for eGFR creatinine (-0.40; p = 0.07).

CONCLUSIONS

Overall, the correlation between cystatin C- or creatinine-based eGFR with PDAY risk score was similar in children. Further studies in children with CKD should explore the association between cystatin C and cardiovascular risk.

Cystatin C and Cardiac Measures in Children and Adolescents With CKD

BACKGROUND

Cardiovascular disease (CVD) is highly prevalent among children with chronic kidney disease (CKD). Cystatin C is an established marker of kidney function and an emerging biomarker for CVD events. We quantified the relationship between cystatin C level and cardiac structure and function over time among children with CKD and assessed whether cystatin C level and diastolic function retained an association after accounting for kidney function.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

678 children and adolescents with mild to moderate CKD enrolled in the CKD in Children (CKiD) Study with 1,228 echocardiographically obtained cardiac structure and function measurements.

PREDICTOR

Serum cystatin C (mg/L) measured annually.

OUTCOMES

Cardiac structure (left ventricular mass index [g/m^2.7]) and cardiac function (shortening fraction; E/A, E'/A', E/E' ratios) measured every other year.

MEASUREMENTS

Demographics and anthropometrics, measured glomerular filtration rate (mGFR), heart rate, blood pressure, hemoglobin z score, serum albumin level, and calcium-phosphorus product.

RESULTS

Independent of time, each 1-mg/L increase in cystatin C level was independently associated with a concurrent 7.7% (95% CI, 5.3%-10.0%) increase in left ventricular mass index, a -4.7% (95% CI, -7.0% to -2.4%) change in E/A ratio, a -6.6% (95% CI, -9.0% to -4.2%) change in E'/A' ratio, and a 2.5% (95% CI, 0.3%-4.7%) increase in E/E' ratio. mGFR was also independently associated with E'/A' ratio. When cystatin C level and mGFR were included in the same model, cystatin C level remained independently associated with E'/A' ratio, whereas mGFR was not.

LIMITATIONS

24% of the cohort was missing data for outcomes of interest or measurements; study population includes only children and adolescents with mild to moderate CKD.

CONCLUSIONS

In this study of children and adolescents with mild to moderate CKD, cystatin C level was independently associated with cardiac structure and diastolic function. Cystatin C level remained able to predict diastolic function decline via E'/A' ratio even after adjusting for mGFR, suggesting that cystatin C level may have an independent role in CVD risk stratification among children and adolescents with CKD.

Association between kidney and cardiac diastolic function in Chinese subjects without overt disease: correlation with ageing and inflammatory markers

BACKGROUND

Age-related changes in kidney structure and function have been well documented. This study aimed to assess the relationship between declines of normal ageing-related kidney function and cardiac diastolic function in a healthy Chinese population.

MATERIALS AND METHODS

A total of 852 healthy adults aged 30-98 years were enrolled and divided into four groups according to quartiles of estimated glomerular filtration rate (eGFR) and cystatin C (CYSC). Cardiac diastolic function was measured by ratio of peak velocity of early filling to peak velocity of atrial filling (E/A), which was derived by B-mode echocardiography. Lower E/A was defined as measures under the 25th percentile of sample distribution (0·784).

RESULTS

Age was significantly associated with eGFR (r = -0·102, P < 0·01), CYSC (r = 0·544, P < 0·01) and E/A (r = -0·381, P < 0·01). Binary logistic regression analysis revealed that second, third and fourth quartile groups of CYSC and fourth quartile of eGFR were significantly associated with lower E/A in an unadjusted model. However, these associations were lost after full adjustment.

CONCLUSIONS

Our results confirm that ageing is a major factor contributing to declines in both kidney and cardiac diastolic function in a healthy population. Adjustment for covariates, however, showed that normal ageing-related declines in kidney function and cardiac diastolic function are not independently linked.

Diastolic dysfunction in paediatric patients on peritoneal dialysis and after renal transplantation

BACKGROUND

Cardiovascular disease is the leading cause of death in children with end-stage renal disease. We investigated the presence of cardiac systolic and diastolic dysfunction in patients on peritoneal dialysis or after renal transplantation. Methods and results. Fourteen patients on peritoneal dialysis for a mean of 1.4 years (range 0.1-5.3) and 39 patients with a functioning kidney transplant for a median time of 3.3 years (range 1.2-14.5) were studied. These patients were compared to 153 age-matched healthy controls. As assessed by echocardiography, both dialysis and transplant patients showed left ventricular dysfunction. Systolic tissue Doppler values were lower as compared to controls. Mitral E/A ratios were significantly lower as well, indicating diastolic dysfunction (transplant 1.82 +/- 0.58 versus 2.15 +/- 0.63, P < 0.01; dialysis patients 1.57 +/- 0.73 versus 2.31 +/- 0.52, P < 0.01). Also, tissue Doppler values were different, showing an increased E/E' ratio in the patients, indicating diastolic dysfunction (transplant 9.49 +/- 1.71 versus 7.50 +/- 1.60, P < 0.01; dialysis patients 11.90 +/- 2.11 versus 8.10 +/- 1.24, P < 0.01). The left ventricular mass index was increased in the transplant patients (controls 25 +/- 7 g/m(2.7); transplant 59 +/- 64 g/m(2.7); P < 0.01), as well as in the dialysis patients (controls 28 +/- 7 g/m(2.7); dialysis 43 +/- 11 g/m(2.7); P < 0.01) and was associated with systolic hypertension (R = 0.46, P < 0.05). High parathyroid hormone (PTH) levels, more prevalent in dialysis patients, were associated with abnormal E/A and E/E' ratios.

CONCLUSIONS

Abnormalities in diastolic function are present in both peritoneal dialysis and renal transplanted patients. In the dialysis group, abnormalities in calcium-phosphate metabolism are associated with diastolic dysfunction. Cardiac hypertrophy was noted in both patient groups and was associated with systolic hypertension.

Association of cystatin C with left ventricular structure and function: the Dallas Heart Study

BACKGROUND

Cystatin C, a novel marker of renal function, has been associated with heart failure and cardiovascular mortality in older individuals. We tested the hypothesis that cystatin C is associated with preclinical cardiac structural and functional abnormalities in a younger population-based sample.

METHODS AND RESULTS

The study included participants in the Dallas Heart Study (ages 30 to 65 years) who had measurements of cystatin C and cardiac MRI. The associations of cystatin C with left ventricular (LV) mass, LV end-systolic and -diastolic volumes, concentricity (LV mass/LV end-diastolic volume), LV wall thickness, and LV ejection fraction were evaluated. Cystatin C levels ranged from 0.46 to 6.55 mg/L. In univariable analyses, increasing levels of cystatin C correlated with higher LV mass, concentricity, and wall thickness (P<0.001), but not with LV end-systolic volume, LV end-diastolic volume, or LV ejection fraction. After adjustment with traditional covariates and estimated glomerular filtration rate by the modification of diet in renal disease formula, log-transformed cystatin C remained independently associated with LV mass (P<0.001), concentricity (P=0.027), and wall thickness (P<0.001). These associations persisted when creatinine or estimated glomerular filtration rate by the Cockcroft-Gault formula were included in the models.

CONCLUSIONS

Higher levels of cystatin C were associated with increased LV mass and a concentric LV hypertrophy phenotype. These findings were independent of potential confounding variables including standard measurements of renal function, supporting the hypothesis that cystatin C may be useful to identify individuals with preclinical structural heart abnormalities.

Cystatin C and risk of heart failure in the Physicians' Health Study (PHS)

BACKGROUND

Chronic kidney disease is a risk factor for heart failure (HF). Although cystatin C can detect early kidney dysfunction, limited data are available on the association between cystatin C and HF.

METHODS

In a prospective nested case-control study design, we examined whether cystatin C is associated with an increased risk of HF in the PHS and whether such an association is stronger in hypertensive subjects. We selected 220 cases of incident HF and 220 controls, matched on age, year of birth, and time of blood collection. Plasma cystatin C was measured using an immunonephelometry method. We used conditional logistic regression to estimate relative risks (RRs).

RESULTS

Compared with the lowest tertile, the multivariable adjusted RR (95% CI) for HF was 1.15 (0.69-1.89) and 1.78 (1.01-3.13) for the second and third tertiles of cystatin C, respectively. Additional adjustment for systolic blood pressure and history of hypertension attenuated this association (RR = 1.0, 1.23 [0.73-2.09], and 1.61 [0.90-2.88] from the lowest to the highest tertile, respectively). Furthermore, we observed a 4-fold increased risk of HF in the second and third tertiles of cystatin C among hypertensive individuals and no meaningful effects of cystatin C on HF among nonhypertensive subjects.

CONCLUSIONS

Our data demonstrated that higher levels of cystatin C are associated with an increased risk of HF and that such association may be limited to hypertensive individuals. Additional studies are warranted to further examine the relationship between hypertension and cystatin C on the risk of HF.

Cystatin C is associated with cardiovascular risk factors and metabolic syndrome in Aboriginal youth

Serum concentration of cystatin C, a marker of glomerular filtration, has been associated with incident cardiovascular disease (CVD), although the pathophysiology underlying this association remains unclear. As North American Aboriginal populations are experiencing high prevalence rates of CVD in early adulthood, evaluation of cardiovascular (CV) risk factors in Aboriginal children may provide insight into the early pathophysiology of vascular disease. In this context, we sought to determine whether cystatin C is associated with CV risk factors in Aboriginal youth. Serum concentrations of cystatin C were assessed in a population-based study of a Canadian Aboriginal community, involving 230 children aged 10-19 years. Cystatin C was higher in the 41 children with pediatric metabolic syndrome (MetS) (defined using an age- and gender-specific version of Adult Treatment Panel III criteria) than in the 189 children free of MetS (0.87 vs 0.81 mg/l, p = 0.0026). After adjustment for age, gender, and glomerular filtration rate (estimated using the Schwartz formula), cystatin C was (1) positively correlated with waist circumference, body mass index, systolic blood pressure, triglycerides, fasting insulin, and leptin (all r >/= 0.18, p < 0.05), and (2) inversely related to high-density lipoprotein (HDL) cholesterol (r = -0.21, p = 0.0023). These associations, however, were attenuated with further adjustment for insulin resistance, as measured by the homeostasis model assessment (HOMA-IR). On multivariate analysis, waist circumference emerged as a positive independent determinant of cystatin C, whereas female gender and age were negative correlates. Cystatin C levels progressively increased in association with the number of metabolic syndrome component disorders coexistent within an individual (trend p = 0.0072). In summary, increased cystatin C is associated with an enhanced CV risk factor profile in Aboriginal youth and may be an early event in the natural history of vascular disease.

Bias and precision of estimated glomerular filtration rate in children

Determining true glomerular filtration rate (GFR) using an exogenous marker is time-consuming and cumbersome. Therefore, creatinine-based estimates of GFR are used. Recent papers using new population-specific/local parameters in their prediction equations, standardizing creatinine determination or adding other endogenous surrogate markers of GFR, like cystatin C, could demonstrate an improvement of bias inherent in the results of the prediction equations. Precision, however, is still poor. Currently, we have to accept a precision (as defined in the so-called Bland-Altman plot) of +/-20% in adults and +/-30-40% in children. This problem of poor precision/uncertainty is especially bothering in the higher, near normal GFR range. Caution should be exercised when applying prediction equations in individuals in need of an accurate GFR determination. In that case, a real clearance procedure has to be performed. In the long run, the true clearance procedure should be simplified using new exogenous GFR markers and developing new devices, allowing GFR measurements to be performed, for example, transcutaneously. Such a procedure would be more acceptable for both patients and physicians.

Cystatin C, left ventricular hypertrophy, and diastolic dysfunction: data from the Heart and Soul Study

BACKGROUND

Impaired kidney function, as measured by serum cystatin C, is associated with risk of incident heart failure. Whether cystatin C is associated with preclinical cardiac structural abnormalities is unknown. We evaluate whether cystatin C is associated with left ventricular hypertrophy, diastolic dysfunction, and systolic dysfunction among 818 outpatients with coronary artery disease who were free of clinical heart failure.

METHODS AND RESULTS

The 818 study participants were categorized into quartiles based on serum cystatin C concentrations, with < or =0.91 mg/L constituting the lowest quartile (I) and > or =1.28 mg/L constituting the highest (IV). Left ventricular hypertrophy (left ventricular mass index >90 g/m(2) by truncated ellipsoid method), diastolic dysfunction (impaired relaxation, pseudo-normal, or restrictive filling patterns) and systolic dysfunction (left ventricular ejection fraction < or =50%) were determined by echocardiography. Left ventricular hypertrophy was present in 68% of participants in quartile IV, compared with 44% of those in quartile I (adjusted odds ratio [OR] 2.17; 95% confidence interval [CI] 1.34 to 3.52; P = .002). Diastolic dysfunction was present in 52% of participants in quartile IV, compared with 24% of those in quartile I (adjusted OR 1.79; 95% CI 1.04 to 3.11; P = .04). Systolic dysfunction was present in 12% of those in quartile IV, compared with 6% of those in quartile I (adjusted OR 1.83; 95% CI 0.75 to 4.46; P = .15).

CONCLUSION

Higher cystatin C concentrations are strongly associated with left ventricular hypertrophy and diastolic dysfunction in outpatients with coronary artery disease and without heart failure.