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.

[Cystatin C: Biomarker of cardiovascular risk in HIV]

INTRODUCTION

Patients infected with the human immunodeficiency virus (HIV) have a higher cardiovascular risk (CVR). The development of cardiovascular disease (CVD) in this population involves traditional CVR factors and factors related to the infection itself, such as chronic inflammatory status, immune dysfunction, as well as the antiretroviral therapy received. Cystatin C (CC) has shown to be useful in assessing the presence of CVR factors and CVD established in the general population, the elderly population, and patients with chronic kidney disease. An analysis was performed on this association in an HIV positive population (HIV+).

MATERIAL AND METHODS

Analytical, observational, cross-sectional study was conducted, and included collecting information about CVR factors and CVD in HIV+, as well as measuring CC. The patients were divided into 2 groups: Group1=high CC (≥0.95mg/L) and Group2=normal CC (<0.95mg/L).

RESULTS

A total of 95 patients were included. Group1=27 (28.4%) and Group2=68 (71.5%). A value of CC≥0.95mg/L was related to the presence of CVD (P=.01). It was also related with and an increase in waist circumference (P=.05), neck circumference (P=.04), systolic blood pressure (P=.04), diastolic blood pressure (P=.01), Framingham score (P=.03), and Framingham score adapted for HIV (P=.01). After performing multivariate analysis with incorporation of variables associated with CVD in the bivariate analysis, only CC≥0.95mg/L continued to be related to CVD.

CONCLUSION

CC≥0.95mg/L was independently associated with CVD. This cut-off point was also linked to higher levels of blood pressure, and higher CVR at 10 years using the Framingham Score and Framingham Score adapted for HIV population.

Comparison of MDRD and the old CKD-EPI equations with the new CKD-EPI equations in kidney transplant patients when glomerular filtration rate is measured with 51Cr-EDTA

BACKGROUND

When estimating the glomerular filtration rate (GFR) in kidney transplant patients, significant differences have been found between MDRD and the 2009 CKD-EPI equations, and reference techniques.

OBJECTIVE

To analyse and compare the performance of MDRD and the 2009 and 2012 CKD-EPI equations against ⁵¹Cr-EDTA plasma clearance in measuring GFR in 270 kidney transplant patients after one year.

RESULTS

The mean measured GFR was 43.0±11.4 (18.2-79.4)ml/min/1.73m², with creatinine levels of 1.42±0.46 (0.60-4.33)mg/dl and cystatin C levels of 1.45±0.53 (0.42-3.48)mg/l. This correlated moderately with creatinine (r=-0.61, P<.001) and cystatin C (r=-0.52, P<.001). Using linear regression techniques, it was found that creatinine, cystatin C, gender and age only explained 52% of GFR total variance. All equations overestimated GFR, with a mean bias of +11.1ml/min/1.73m² for MDRD, +16.4ml/min/1.73m² for 2009-CKD-EPI, +15ml/min/1.73m² for CKD-EPI with cystatin C, and +14.1ml/min/1.73m² for 2012-CKD-EPI with creatinine and cystatin C. eGFR by MDRD and the 2009 CKD-EPI equation correlated better with ⁵¹Cr-EDTA than CKD-EPI with creatinine and/or cystatin C. The overestimations were negatively correlated with creatinine and cystatin C levels, most significantly for CKD-EPI with creatinine and/or cystatin C when GFR was greater than 60ml/min/1.73m².

CONCLUSIONS

The 2012 CKD-EPI equations with creatinine and/or cystatin C significantly overestimate GFR in stage 1 and 2 chronic kidney disease. The MDRD equations is therefore recommended in these cases. The reference method used to measure GFR seems to heavily influence the bias of the equations.

Influence of age, gender, smoking, diabetes, thyroid and cardiac dysfunctions on cystatin C biomarker

BACKGROUND

Creatinine is the most widely used renal failure biomarker; however, it has a lot of drawbacks. One of the major drawbacks is the blind range (does not increase until 50% of the kidney deteriorates). On the other hand, cystatin C has gained more attention as a promising biomarker due to several advantages over creatinine. Cystatin C levels are elevated as soon as any mild defect in the kidney occurs. Furthermore, cystatin C is influenced by several non-renal diseases which provide an additional prognostic value for this promising biomarker.

OBJECTIVES

1. Study the effects of age, gender and smoking on cystatin C levels to. 2. Challenge the adoption of glomerular filtration rate equations for healthy population. 3. Compare the values generated from different glomerular filtration rate equations. 4. Evaluate the prognostic value of cystatin C for selected non-renal diseases.

METHODS

Using cross sectional analyses, we established the relationship between cystatin C levels and non-renal predictors. The quantification of cystatin C was performed by high performance liquid chromatographic method, while for creatinine by a colorimetric enzymatic method.

RESULTS

In the healthy volunteers the levels of cystatin C were slightly higher in men than in women and in individuals older than 50 years old than those under 50 years old and in smokers than non-smokers, however, statistical data confirmed a non-significant relationship with respect to the aforementioned factors. For the recruited patients suffering from (diabetes, hyper- and hypothyroidism and cardiac dysfunctions) a clear increase in cystatin C levels were observed with the exception of hypothyroidism patients in which a decrease in their cystatin C levels were observed.

CONCLUSION

Diabetes, thyroid and cardiac dysfunctions have a clear impact on the levels of cystatin C in human blood, whereas age, gender and smoking habit have no effect. Therefore, cystatin C could be considered as a useful biomarker of the aforementioned diseases, in turn, this requires extra precautions including the evaluation of several clinical conditions by physicians should CC is considered as a renal failure biomarker.

Absence of cystatin C involvement in ventricular remodelling and heart failure

Cystatin C (CysC) is a protease encoded by housekeeping genes. Although its prognostic value in heart failure (HF) is well known, it is debatable whether this value is due to the greater accuracy of CysC in calculating the glomerular filtration rate or to its involvement in pathological ventricular remodelling. The aim of this study was to determine whether CysC expression changes in the myocardium of foetuses of different ages and in the myocardium of adults with various cardiovascular diseases, as well as to analyse the correlation between its serum concentrations and cardiac structure and morphology in a patient group with HF.

PATIENTS AND METHODS

We analysed the correlations (Pearson's r and Spearman's test) between the serum CysC levels and echocardiographic parameters of 351 patients with HF. We also performed immunohistochemical staining for CysC, metalloproteinase-9 (MMP-9) and desmin in 9 cardiac tissue samples from autopsies of 4 foetuses of different gestational ages and 5 healthy adults or adults with cardiovascular disease.

RESULTS

For the patients with HF, there was no correlation between the CysC concentrations and the cardiac parameters measured by 2D echocardiography. The immunohistochemistry showed a weak background staining for CysC in all samples, regardless of age and the presence or absence of cardiovascular diseases.

CONCLUSIONS

Our results suggest that CysC does not have a significant role in the pathological remodelling of the left ventricle in HF.

Serum cystatin C levels in preterm newborns in our setting: Correlation with serum creatinine and preterm pathologies

BACKGROUND

Cystatin C (CysC) is a renal function marker that is not as influenced as creatinine (Cr) by endogenous or exogenous agents, so it is therefore proposed as a marker in preterm infants.

OBJECTIVES

To determine serum CysC values in preterm infants during the first week of life, compared to Cr. To analyze alterations caused by prematurity diseases.

METHOD

The design involved a longitudinal, observational study of prospective cohorts. Groups were based on gestational age (GA): Group A (24-27 weeks), Group B (28-33 weeks), Group C (34-36 weeks). Blood samples were collected at birth, within 48-72hours and after 7 days of life.

STATISTICS

SPSS v.20 software was used. The statistical methods applied included chi-squared test and ANOVA.

RESULTS

A total of 109 preterm infants were included in the study. CysC levels were: 1.54mg/L (±0.28) at birth; 1.38mg/L (±0.36) within 48-72hours of life; 1.50mg/L (±0.31) after 7 days (p<0.05). Cr levels were: 0.64mg/dL (±0.17) at birth; 0.64mg/dL (±0.28) within 48-72hours; 0.56mg/dL (±0.19) after 7 days (P<.05). CysC values were lower in hypotensive patients and those with a respiratory disease (P<.05), and no alterations associated with other diseases were observed. There were no differences in Cr levels associated with any disease. Creatinine levels were higher in patients ≤1.500g (P<.05).

CONCLUSIONS

Serum CysC decreased within 48-72hours of life, and this decline showed significance (P<.05). The levels increased after 7 days in all 3 GA groups, and there was no difference in CysC levels among the groups. More studies in preterm infants with hypotension and respiratory disease are required. CysC is a better glomerular filtration (GF) marker in ≤1.500g preterm infants.

[Usefulness of cystatin C as a prognostic marker in venous thromboembolism]

BACKGROUND AND OBJECTIVE

Cystatin C (cysC) is a prognostic marker in patients with hypertension, coronary heart disease and heart failure. The aim of this study was to determine the prognostic value of cysC levels obtained at the time of diagnosis in patients with venous thromboembolism (VTE).

MATERIAL AND METHOD

Retrospective study of a cohort of 226 consecutive patients with VTE, followed for 6 months. Serum samples were obtained for the determination of cysC, creatinine, and the N-terminal fraction of the brain natriuretic peptide (NT-proBNP) at the time of diagnosis.

RESULTS

The highest discriminating power value of dying at 6 months for cysC was 1,175mg/dl (sensitivity 76%, specificity 65%, positive predictive value 26%, negative predictive value 94%). Above the cut-off, 17/48 patients died, versus 9/152 that had lower levels (odds ratio: 5.98, 95% confidence interval [95% CI]: 2.50-14.29, P<.001). The adjusted hazard ratio in a multivariate model was 3.76 (95% CI 1.46-9.66). The accuracy of this parameter was similar to that for creatinine (1.24mg/dl) but lower than the NT-proBNP (435pg/ml). Patients who exceeded the limit values of cysC and NT-proBNP together had no greater risk of death than those above NT-proBNP only (odds ratio: 9.43, 95% CI 3.90-22.81, P<.001). There was no value, which was significantly associated with bleeding episodes or recurrent thromboembolism.

CONCLUSION

CysC concentration at the time of diagnosis in VTE patients has prognostic value, which is similar to that of serum creatinine and lower than that of NT-proBNP.

Cystatin C as an early marker of acute kidney injury in septic shock

OBJECTIVE

To describe the utility of determining plasma cystatinC concentrations in the diagnosis of acute incident kidney injury in septic shock.

PATIENTS AND METHODS

Prospective series of 50 patients with septic shock and plasma creatinine levels <2mg/dL hospitalized in an intensive care unit. Clinical and laboratory follow-ups were conducted, with measurements of cystatinC, urea and plasma creatinine levels from the diagnosis of septic shock to 5days later. The severity of the septic shock was assessed with the RIFLE scale.

RESULTS

Twenty patients (40%) developed acute kidney injury: 8 (16%) were categorized as RIFLE-R, 5 (10%) as RIFLE-I and 7 (14%) as RIFLE-F. All patients categorized as RIFLE-F required extracorporeal renal clearance. Eighteen (36%) patients died, 8 (20%) of whom had developed acute kidney injury in their evolution. There was poor correlation between plasma creatinine and cystatin C levels (r=.501; P=.001), which disappeared upon reaching any degree of renal impairment on the RIFLE scale. CystatinC levels increased earlier and were better able to identify patients who would develop serious renal function impairment (RIFLE-F) than creatinine and urea levels. The initial cystatinC levels were related to mortality at 30days (OR=1.16; 95%CI: 03-.85).

CONCLUSIONS

For patients who developed acute septic kidney injury, the plasma cystatinC levels increased before the classical markers of renal function. CystatinC also constitutes a severity biomarker that correlates with progression to RIFLE-F, the need for extrarenal clearance and, ultimately, mortality. This precocity could be useful for starting measures that prevent the progression of renal dysfunction.

Clinical analysis of the relationship between cystatin C and metabolic syndrome in the elderly

OBJECTIVE

Studies have shown that both cystatin C and metabolic syndrome (MetS) are associated with inflammation. We set out to investigate the correlation between serum cystatin C levels and MetS in the elderly.

METHODS

This prospective study was conducted in 380 elderly individuals, including 135 patients with MetS, 142 patients with metabolic disturbance (MetD), and 103 healthy elderly individuals (control group). Waist-hip ratio, waist circumference, waist-height ratio, body mass index (BMI), fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), high-density lipoprotein (HDL-C), systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure and cystatin C were measured and their mutual relations were analyzed.

RESULTS

The higher the MetS scores, the higher the serum cystatin C concentration in these patients. Serum cystatin C concentration was closely related to waist-hip ratio, waist circumference, waist-height ratio, BMI, TG, FPG, and blood pressure, not related to LDL-C levels, and negatively correlated with HDL-C levels. Logistic regression analysis indicated that cystatin C, waist-height ratio, waist circumference, FPG, TG, SBP and pulse pressure were significantly associated with MetS (OR between cystatin C and MetS 2.164, 95% CI 1.136-8.259).

CONCLUSION

Cystatin C was significantly associated with MetS in the elderly. As MetS scores rose, serum cystatin C levels increased.

Multimarker approach with cystatin C, N-terminal pro-brain natriuretic peptide, C-reactive protein and red blood cell distribution width in risk stratification of patients with acute coronary syndromes

INTRODUCTION AND AIM

Biomarkers have emerged as interesting predictors of risk in patients with acute coronary syndromes (ACS). The aim of this study was to determine the utility of the combined measurement of cystatin C (CysC), C-reactive protein (CRP), N-terminal pro-brain natriuretic peptide (NT-proBNP) and red blood cell distribution width (RDW) in the risk stratification of patients with ACS.

METHODS

In this prospective study including 682 patients consecutively admitted to a coronary care unit for ACS, baseline measurements of CysC, CRP, NT-proBNP and RDW were performed. Patients were categorized on the basis of the number of elevated biomarkers at presentation. The primary outcome was 6-month mortality.

RESULTS

The number of biomarkers elevated on admission (study score) was an independent predictor of 6-month mortality; patients with four biomarkers elevated on admission had a significantly higher risk of 6-month mortality compared with patients with none or one. In addition, in patients with high risk defined by the GRACE score, our multimarker score was able to further categorize their risk of 6-month mortality.

CONCLUSIONS

A multimarker approach using CysC, NT-proBNP, CRP and RDW was an independent predictor of 6-month mortality and added prognostic information to the GRACE risk score in patients with ACS and high risk defined by GRACE, with increasing mortality in patients with a higher number of elevated biomarkers on admission.