Estimated glomerular filtration rate and renal resistive index as possible predictive markers of mortality in systemic sclerosis

Association of renal resistive indices with kidney disease progression and mortality

BACKGROUND

Renal resistive indices (RRI) have been shown to predict the progression of kidney disease. This study aims to evaluate the association of RRI with mortality and dialysis initiation after adjustment to therapeutic and life style interventions.

METHODS

This is a retrospective study that included all chronic kidney disease patients followed for at least two years in three nephrology clinics between 2006 and 2019 and who had a RRI level in their files. Kaplan Meier and log rank test compared the survival of patients with normal versus high RRI. Cox regression analysis evaluated the association between RRI and death or dialysis initiation after adjustment to treatments and life style modifications.

RESULTS

A total of 192 patients were analyzed: 68 had RRI < 0.7 and 124 had RRI ≥ 0.7. Their mean age was 66.5 ± 13.1 years at first visit, 78.1% were males. There was a negative correlation between baseline eGFR and RRI (p < 0.001; Spearman correlation coefficient = -0.521). The survival was significantly better in patients with RRI < 0.7 with a Log Rank test < 0.001. The univariate cox regression analysis showed a significant association between RRI and mortality (HR = 1.08; 95%CI: 1.04-1.11; p < 0.001) that remained significant after adjustment to cardiovascular risk factors and interventions such as salt reduction, blood pressure control, statins and RAAS inhibitors (HR = 1.04; 95%CI: 1.00-1.08; p = 0.036). Cox regression analysis showed a significant association between RRI and dialysis initiation (HR = 1.06; 95%CI 1.01-1.10; p = 0.011).

CONCLUSION

Our study revealed that patients with an elevated RRI ≥ 0.7 are at a higher risk of mortality after adjustment to medications and lifestyle modifications. RRI can, according to this study, be considered as an independent prognostic factor in CKD patients.

Current Insights into the Significance of the Renal Resistive Index in Kidney and Cardiovascular Disease

Initially, the renal resistive index (RRI) was investigated with the aim of improving diagnosis in kidney diseases, but this goal was not met. Recently, many papers have highlighted the prognostic significance of the RRI in chronic kidney disease: specifically, in estimating the revascularization success of renal artery stenoses or the evolution of the graft and the recipients in renal transplantation. Moreover, the RRI has become significant in the prediction of acute kidney injury in critically ill patients. Studies in renal pathology have revealed correlations of this index with parameters of systemic circulation. The theoretical and experimental premises of this connection were then reconsidered, and studies analyzing the link between RRI and arterial stiffness, central and peripheral pressure, and left ventricular flow were conducted with this purpose. Many data currently indicate that RRI is influenced more by pulse pressure and vascular compliance than by renal vascular resistance-assuming that RRI reflects the complex interplay between systemic circulation and renal microcirculation and should be considered a marker of systemic cardiovascular risk beyond its prognostic relevance for kidney disease. In this review, we overview the clinical research that reveals the implications of RRI in renal and cardiovascular disease.

Phase angle, nutritional status, and mortality in systemic sclerosis: An exploratory pilot study

OBJECTIVES

Systemic sclerosis (SSc) is a rare autoimmune disease characterized by microvascular damage and fibrosis of the skin and internal organs. Among SSc complications, changes in nutritional status have a negative effect on quality of life and predispose patients to malnutrition. The aim of this exploratory pilot study was to examine whether bioelectrical impedance analysis-derived phase angle (PhA) is a parameter of nutritional status and a marker of mortality in patients with SSc.

METHODS

Consecutive adult patients with SSc were included in the study. Biochemical analyses, anthropometric data, and bioelectrical impedance analysis assessments were recorded at the time of enrollment. The Malnutrition Universal Screening Tool (MUST) and Global Leadership Initiative on Malnutrition (GLIM) were applied to assess nutritional status.

RESULTS

A total of 104 patients with SSc (88 women; median age: 55 y [interquartile range (IQR), 45.5- 66 y]) were enrolled. In patients with SSc and high malnutrition risk according to MUST, mean values of PhA were significantly lower than those of patients with SSc and low malnutrition risk (4° [IQR, 3.7°-4.4°] vs 4.6° [IQR, 4.2°-5.1°]; P = 0.004). Patients with SSc and malnutrition according to the GLIM criteria showed significantly lower PhA than patients with SSc but without malnutrition (3.8° [IQR, 3.5°-4.3°] vs 4.6° [IQR, 4.2°-5.1°]; P < 0.0001). Kaplan-Meier curves demonstrated that overall survival was significantly shorter (34.57 mo [±13.35] vs 48 mo [±0]; P = 0.001) in patients with SSc and PhA <3.75°. In the multivariate analysis, only PhA was a predictive factor for death (hazard ratio: 0.283; 95% confidence interval, 0.083-0.965; P = 0.044).

CONCLUSIONS

The data obtained suggest that lower PhA values in patients with SSc are associated with an increased malnutrition risk with MUST, malnutrition with GLIM, and increased mortality. Additional studies are necessary to confirm these preliminary results.

[Renal manifestations in connective tissue diseases]

Connective tissue diseases (CTD) comprise a group of inflammatory systemic diseases that can affect various organs. Kidney involvement is frequently associated with significant irreversible damage and often before patients become symptomatic. Screening tests of blood and urine as well as clinical vigilance are therefore essential for all CTDs with possible renal involvement. A kidney biopsy is the gold standard for the diagnosis, prognosis and treatment decisions. A common and severe organ involvement in systemic lupus erythematosus (SLE) is glomerulonephritis (GN), also collectively referred to as lupus nephritis (LN). If left untreated LN often leads to end-stage renal failure. The treatment depends on the clinical parameters and histopathology of the renal involvement. Mycophenolate mofetil and cyclophosphamide are potent but nonspecific immunosuppressants which have been available for many years. Recently, new substances specific for LN have also been approved for the first time. Kidney involvement in Sjogren's syndrome has been far less studied. In studies the frequency of renal involvement is still unclear and ranges from 5% to 33%. Tubulointerstitial nephritis (IN) is the typical form of renal involvement which clearly differs from GN in its clinical presentation. Recommendations for treatment are based exclusively on retrospective studies. A renal crisis in systemic scleroderma (SSc) is a rare but feared complication with a high mortality. An antiphospholipid syndrome (APS) nephropathy (APSN) can occur during CTD. These entities are vasculopathies and often thrombotic microangiopathies, which clearly differ from GN and IN in terms of pathophysiology, clinical features and treatment. This article provides an overview of the diversity of the most important renal manifestations of CTDs.

Zibotentan in systemic sclerosis-associated chronic kidney disease: a phase II randomised placebo-controlled trial

Background

We report results from a phase II randomised placebo-controlled trial assessing zibotentan, a highly selective endothelin receptor antagonist (ERA), in chronic kidney disease (CKD) secondary to systemic sclerosis (SSc).

Methods

This trial included three sub-studies: ZEBRA 1—a randomised placebo-controlled, double-blind trial of zibotentan in SSc patients with CKD2 or CKD3 (and glomerular filtration rate (GFR) >45 ml/min) over 26 weeks; ZEBRA 2A—a 26-week placebo-controlled, single-blind trial of zibotentan in scleroderma renal crisis patients not requiring dialysis; and ZEBRA 2B—an open label pharmacokinetic study of zibotentan in patients on haemodialysis.

Results

Sixteen patients were screened for ZEBRA 1. Of these, 6 patients were randomised to zibotentan and 7 to placebo. In ZEBRA 1, there were 47 non-serious adverse events (AE) during the trial. Twenty-seven occurred in the placebo group and 20 in the zibotentan group. One serious adverse event (SAE) occurred during ZEBRA1, in the placebo arm. Descriptive statistics did not suggest an effect of study drug on serum sVCAM1. Estimated GFR numerically declined in patients treated with placebo at 26 weeks and 52 weeks. In contrast, average eGFR increased in zibotentan-treated cases.

The 4 patients in ZEBRA 2A experienced 8 non-serious AEs, distributed equally between placebo and zibotentan. There was one SAE each in placebo and zibotentan groups, both unrelated to study medication.

ZEBRA 2B recruited 8 patients, 6 completed first dosing, and 2 completed a second dosing visit. Pharmacokinetic analysis confirmed zibotentan levels within the therapeutic range. Three patients experienced 3 non-serious AEs. One SAE occurred and was unrelated to study drug.

Conclusions

Zibotentan was generally well-tolerated. ZEBRA 1 did not show any effect of zibotentan on serum sVCAM-1 but was associated with numerical improvement in eGFR at 26 weeks that was more marked at 52 weeks. ZEBRA 2B suggested a feasible dose regimen for haemodialysis patients.

Trial registration

EudraCT no: 2013-003200-39 (first posted January 28, 2014)

ClinicalTrials.gov Identifier: NCT02047708

Sponsor protocol number: 13/0077