Prevention of contrast-induced AKI: a review of published trials and the design of the prevention of serious adverse events following angiography (PRESERVE) trial

Pyridoxamine reduces postinjury fibrosis and improves functional recovery after acute kidney injury

Acute kidney injury (AKI) is a common and independent risk factor for death and chronic kidney disease (CKD). Despite promising preclinical data, there is no evidence that antioxidants reduce the severity of injury, increase recovery, or prevent CKD in patients with AKI. Pyridoxamine (PM) is a structural analog of vitamin B6 that interferes with oxidative macromolecular damage via a number of different mechanisms and is in a phase 3 clinical efficacy trial to delay CKD progression in patients with diabetic kidney disease. Because oxidative stress is implicated as one of the main drivers of renal injury after AKI, the ability of PM to interfere with multiple aspects of oxidative damage may be favorable for AKI treatment. In these studies we therefore evaluated PM treatment in a mouse model of AKI. Pretreatment with PM caused a dose-dependent reduction in acute tubular injury, long-term postinjury fibrosis, as well as improved functional recovery after ischemia-reperfusion AKI (IR-AKI). This was associated with a dose-dependent reduction in the oxidative stress marker isofuran-to-F2-isoprostane ratio, indicating that PM reduces renal oxidative damage post-AKI. PM also reduced postinjury fibrosis when administered 24 h after the initiating injury, but this was not associated with improvement in functional recovery after IR-AKI. This is the first report showing that treatment with PM reduces short- and long-term injury, fibrosis, and renal functional recovery after IR-AKI. These preclinical findings suggest that PM, which has a favorable clinical safety profile, holds therapeutic promise for AKI and, most importantly, for prevention of adverse long-term outcomes after AKI.

Bridging translation for acute kidney injury with better preclinical modeling of human disease

The current lack of effective therapeutics for patients with acute kidney injury (AKI) represents an important and unmet medical need. Given the importance of the clinical problem, it is time for us to take a few steps back and reexamine current practices. The focus of this review is to explore the extent to which failure of therapeutic translation from animal studies to human studies stems from deficiencies in the preclinical models of AKI. We will evaluate whether the preclinical models of AKI that are commonly used recapitulate the known pathophysiologies of AKI that are being modeled in humans, focusing on four common scenarios that are studied in clinical therapeutic intervention trials: cardiac surgery-induced AKI; contrast-induced AKI; cisplatin-induced AKI; and sepsis associated AKI. Based on our observations, we have identified a number of common limitations in current preclinical modeling of AKI that could be addressed. In the long term, we suggest that progress in developing better preclinical models of AKI will depend on developing a better understanding of human AKI. To this this end, we suggest that there is a need to develop greater in-depth molecular analyses of kidney biopsy tissues coupled with improved clinical and molecular classification of patients with AKI.

Delayed Consequences of Acute Kidney Injury

Acute kidney injury (AKI) is an increasingly common complication of hospitalization and acute illness. Experimental data indicate that AKI may cause permanent kidney damage through tubulointerstitial fibrosis and progressive nephron loss, while also lowering the threshold for subsequent injury. Furthermore, preclinical data suggest that AKI may also cause distant organ dysfunction. The extension of these findings to human studies suggests long-term consequences of AKI including, but not limited to recurrent AKI, progressive kidney disease, elevated blood pressure, cardiovascular events, and mortality. As the number of AKI survivors increases, the need to better understand the mechanisms driving these processes becomes paramount. Optimizing care for AKI survivors will require understanding the short- and long-term risks associated with AKI, identifying patients at highest risk for poor outcomes, and testing interventions that target modifiable risk factors. In this review, we examine the literature describing the association between AKI and long-term outcomes and highlight opportunities for further research and potential intervention.

Risk Stratification for Acute Kidney Injury: Are Biomarkers Enough?

Acute kidney injury (AKI) is a common and serious complication that is associated with several adverse outcomes in hospitalized patients. AKI significantly increases the risk of mortality, need for renal replacement therapy, and intensive care admission, and it also has serious economic ramifications. Effective risk stratification to identify patients at risk for severe AKI is essential for targeting our health care and research resources to tackle this important public health issue. The overwhelming majority of research in earlier diagnosis and risk stratification of AKI over the past 10 years has focused on novel biomarker development. The purpose of this review is to provide an update on other novel risk stratification tools than can be used in the prognostication of AKI. We discuss the utility of the furosemide stress test in predicting the severity of AKI and the renal angina index in predicting the occurrence of AKI. We also discuss NephroCheck, a prognostic test that measures tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 for the early detection of severe AKI.

Renal protection in cardiovascular surgery

Acute kidney injury (AKI) is one of the most relevant complications after major surgery and is a predictor of mortality. In Western countries, patients at risk of developing AKI are mainly those undergoing cardiovascular surgical procedures. In this category of patients, AKI depends on a multifactorial etiology, including low ejection fraction, use of contrast media, hemodynamic instability, cardiopulmonary bypass, and bleeding. Despite a growing body of literature, the treatment of renal failure remains mainly supportive (e.g. hemodynamic stability, fluid management, and avoidance of further damage); therefore, the management of patients at risk of AKI should aim at prevention of renal damage. Thus, the present narrative review analyzes the pathophysiology underlying AKI (specifically in high-risk patients), the preoperative risk factors that predispose to renal damage, early biomarkers related to AKI, and the strategies employed for perioperative renal protection. The most recent scientific evidence has been considered, and whenever conflicting data were encountered possible suggestions are provided.

Management of Acute Kidney Injury and Acid-Base Balance in the Septic Patient

Acute kidney injury (AKI) is an abrupt decrease in kidney function that takes place over hours to days. Sepsis is the leading cause of AKI and portends a particularly high morbidity and mortality, although the severity may vary from a transient rise in serum creatinine to end-stage renal disease. With regard to acid-base management in septic AKI, caution should be used with hyperchloremic crystalloid solutions, and dialysis is often used in the setting of severe acidosis. In the future, biomarkers may help clinicians identify AKI earlier and allow for potential interventions before the development of severe AKI.

Candidate Surrogate End Points for ESRD after AKI

AKI, a frequently transient condition, is not accepted by the US Food and Drug Association as an end point for drug registration trials. We assessed whether an intermediate-term change in eGFR after AKI has a sufficiently strong relationship with subsequent ESRD to serve as an alternative end point in trials of AKI prevention and/or treatment. Among 161,185 United States veterans undergoing major surgery between 2004 and 2011, we characterized in-hospital AKI by Kidney Disease Improving Global Outcomes creatinine criteria and decline in eGFR from prehospitalization to postdischarge time points and quantified associations of these values with ESRD and mortality over a median of 3.8 years. An eGFR decline of ≥30% at 30, 60, and 90 days after discharge occurred in 3.1%, 2.5%, and 2.6%, of survivors without AKI and 15.9%, 12.2%, and 11.7%, of survivors with AKI. For patients with in-hospital AKI compared with those with no AKI and stable eGFR, a 30% decline in eGFR at 30, 60, and 90 days after discharge demonstrated adjusted hazard ratios (95% confidence intervals) of ESRD of 5.60 (4.06 to 7.71), 6.42 (4.76 to 8.65), and 7.27 (5.14 to 10.27), with corresponding estimates for 40% decline in eGFR of 6.98 (5.21 to 9.35), 8.03 (6.11 to 10.56), and 10.95 (8.10 to 14.82). Risks for mortality were smaller but consistent in direction. A 30%-40% decline in eGFR after AKI could be a surrogate end point for ESRD in trials of AKI prevention and/or treatment, but additional trial evidence is needed.

Preventing Contrast-induced Renal Failure: A Guide

Contrast-induced acute kidney injury (CI-AKI) is characterised by a rapid deterioration of renal function within a few days of parenteral administration of contrast media (CM) in the absence of alternative causes. CI-AKI is the most common form of iatrogenic kidney dysfunction with an estimated prevalence of 12 % in patients undergoing percutaneous coronary intervention. Although usually self-resolving, in patients with pre-existing chronic kidney disease (CKD) or concomitant risk factors for renal damage, CI-AKI is associated with increased short-and long-term morbidity and mortality. Therefore, risk stratification based on clinical and peri-procedural characteristics is crucial in selecting patients at risk of CI-AKI who would benefit the most from implementation of preventive measures.

Bridging Translation by Improving Preclinical Study Design in AKI

Despite extensive research, no therapeutic interventions have been shown to prevent AKI, accelerate recovery of AKI, or reduce progression of AKI to CKD in patients. This failure in translation has led investigators to speculate that the animal models being used do not predict therapeutic responses in humans. Although this issue continues to be debated, an important concern that has not been addressed is whether improvements in preclinical study design can be identified that might also increase the likelihood of translating basic AKI research into clinical practice using the current models. In this review, we have taken an evidence-based approach to identify common weaknesses in study design and reporting in preclinical AKI research that may contribute to the poor translatability of the findings. We focused on use of N-acetylcysteine or sodium bicarbonate for the prevention of contrast-induced AKI and use of erythropoietin for the prevention of AKI, two therapeutic approaches that have been extensively studied in clinical trials. On the basis of our findings, we identified five areas for improvement in preclinical study design and reporting. These suggested and preliminary guidelines may help improve the quality of preclinical research for AKI drug development.

Risk prediction models for contrast induced nephropathy: systematic review

OBJECTIVES

To look at the available literature on validated prediction models for contrast induced nephropathy and describe their characteristics.

DESIGN

Systematic review.

DATA SOURCES

Medline, Embase, and CINAHL (cumulative index to nursing and allied health literature) databases.

REVIEW METHODS

Databases searched from inception to 2015, and the retrieved reference lists hand searched. Dual reviews were conducted to identify studies published in the English language of prediction models tested with patients that included derivation and validation cohorts. Data were extracted on baseline patient characteristics, procedural characteristics, modelling methods, metrics of model performance, risk of bias, and clinical usefulness. Eligible studies evaluated characteristics of predictive models that identified patients at risk of contrast induced nephropathy among adults undergoing a diagnostic or interventional procedure using conventional radiocontrast media (media used for computed tomography or angiography, and not gadolinium based contrast).

RESULTS

16 studies were identified, describing 12 prediction models. Substantial interstudy heterogeneity was identified, as a result of different clinical settings, cointerventions, and the timing of creatinine measurement to define contrast induced nephropathy. Ten models were validated internally and six were validated externally. Discrimination varied in studies that were validated internally (C statistic 0.61-0.95) and externally (0.57-0.86). Only one study presented reclassification indices. The majority of higher performing models included measures of pre-existing chronic kidney disease, age, diabetes, heart failure or impaired ejection fraction, and hypotension or shock. No prediction model evaluated its effect on clinical decision making or patient outcomes.

CONCLUSIONS

Most predictive models for contrast induced nephropathy in clinical use have modest ability, and are only relevant to patients receiving contrast for coronary angiography. Further research is needed to develop models that can better inform patient centred decision making, as well as improve the use of prevention strategies for contrast induced nephropathy.

Mitochondrial reactive oxygen species at the heart of the matter: new therapeutic approaches for cardiovascular diseases

Reactive oxygen species (ROS) have been implicated in a variety of age-related diseases, including multiple cardiovascular disorders. However, translation of ROS scavengers (antioxidants) into the clinic has not been successful. These antioxidants grossly reduce total levels of cellular ROS including ROS that participate in physiological signaling. In this review, we challenge the traditional antioxidant therapeutic approach that targets ROS directly with novel approaches that improve mitochondrial functions to more effectively treat cardiovascular diseases.

Contrast-associated AKI in the critically ill: relevant or irrelevant?

PURPOSE OF REVIEW

Iodinated contrast media are frequently administered in ICU patients. Recent studies challenge the relevance of contrast media toxicity in ICU patients and relate occurrence of acute kidney injury to baseline characteristics and severity of illness.

RECENT FINDINGS

Various findings in studies with kidney biomarkers indicate the causal relationship between contrast media exposure and kidney damage. Contrast media exposure not only causes direct tubular damage and renal hypoperfusion but also initiates the formation of reactive oxygen species in its turn causing tissue damage. The route of administration determines the incidence of contrast-induced acute kidney injury with a higher incidence when contrast media are administered by intra-arterial route versus intravenous route. The impact of contrast-associated acute kidney injury on hospital length of stay, the need for renal replacement therapy and survival remains a matter of debate because of discrepancies between observational versus case-matched studies and limitations of the individual studies.

SUMMARY

There are diverse pathophysiologic mechanisms explaining the causal relationship between the administration of contrast media and the development of acute kidney injury. Some studies challenge the relevance of contrast media toxicity in ICU patients. However, limitations of the available studies in ICU patients preclude firm conclusions. A precautionary approach in the administration of contrast media is justified.

Critical care in the emergency department: acute kidney injury

Acute kidney injury (AKI) is common among emergency department patients admitted to hospital. There is evidence of inadequate management of the condition leading to adverse outcomes. We present an illustrative case of AKI complicating a gastrointestinal disorder in an older adult. We discuss the clinical presentation, assessment and management of AKI with reference to recent consensus guidelines on classification and treatment.

Should acetylcysteine be used to prevent contrast induced nephropathy?

Diagnostic and therapeutic procedures that require the infusion of iodine containing contrast solutions are associated with the risk of contrast-induced nephropathy, a condition that can cause significant morbidity. Acetylcysteine has been proposed as a measure to prevent this condition. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified 20 systematic reviews including 64 randomized trials. We combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded that even though acetylcysteine might not cause important adverse effects, it does not decrease need for dialysis, mortality or other important outcomes.

Drug-induced impairment of renal function

Pharmaceutical agents provide diagnostic and therapeutic utility that are central to patient care. However, all agents also carry adverse drug effect profiles. While most of these are clinically insignificant, some drugs may cause unacceptable toxicity that impacts negatively on patient morbidity and mortality. Recognizing adverse effects is important for administering appropriate drug doses, instituting preventive strategies, and withdrawing the offending agent due to toxicity. In the present article, we will review those drugs that are associated with impaired renal function. By focusing on pharmaceutical agents that are currently in clinical practice, we will provide an overview of nephrotoxic drugs that a treating physician is most likely to encounter. In doing so, we will summarize risk factors for nephrotoxicity, describe clinical manifestations, and address preventive and treatment strategies.

Reducing contrast-induced acute kidney injury using a regional multicenter quality improvement intervention

BACKGROUND

Contrast-induced acute kidney injury (CI-AKI) is associated with increased morbidity and mortality after percutaneous coronary interventions and is a patient safety objective of the National Quality Forum. However, no formal quality improvement program to prevent CI-AKI has been conducted. Therefore, we sought to determine whether a 6-year regional multicenter quality improvement intervention could reduce CI-AKI after percutaneous coronary interventions.

METHODS AND RESULTS

We conducted a prospective multicenter quality improvement study to prevent CI-AKI (serum creatinine increase ≥0.3 mg/dL within 48 hours or ≥50% during hospitalization) among 21 067 nonemergent patients undergoing percutaneous coronary interventions at 10 hospitals between 2007 and 2012. Six intervention hospitals participated in the quality improvement intervention. Two hospitals with significantly lower baseline rates of CI-AKI, which served as benchmark sites and were used to develop the intervention, and 2 hospitals not receiving the intervention were used as controls. Using time series analysis and multilevel poisson regression clustering to the hospital level, we calculated adjusted risk ratios for CI-AKI comparing the intervention period to baseline. Adjusted rates of CI-AKI were significantly reduced in hospitals receiving the intervention by 21% (risk ratio, 0.79; 95% confidence interval: 0.67-0.93; P=0.005) for all patients and by 28% in patients with baseline estimated glomerular filtration rate <60 mL/min per 1.73 m(2) (risk ratio, 0.72; 95% confidence interval: 0.56-0.91; P=0.007). Benchmark hospitals had no significant changes in CI-AKI. Key qualitative system factors associated with improvement included multidisciplinary teams, limiting contrast volume, standardized fluid orders, intravenous fluid bolus, and patient education about oral hydration.

CONCLUSIONS

Simple cost-effective quality improvement interventions can prevent ≤1 in 5 CI-AKI events in patients with undergoing nonemergent percutaneous coronary interventions.

Pharmacologic Prophylaxis for Contrast-Induced Acute Kidney Injury

In the effort to prevent contrast-induced acute kidney injury (CI-AKI), several pharmacologic agents have been tested for their single or combined nephroprotective properties. To date, however, no drug has been officially approved for this aim. This article focuses on the three agents that have been most extensively studied: statins, N-acetylcysteine, and ascorbic acid. Particular attention is paid to the impact of these drugs on the CI-AKI prevention and improved prognosis.

Side effects of radiographic contrast media: pathogenesis, risk factors, and prevention

Radiocontrast media (RCM) are medical drugs used to improve the visibility of internal organs and structures in X-ray based imaging techniques. They may have side effects ranging from itching to a life-threatening emergency, known as contrast-induced nephropathy (CIN). We define CIN as acute renal failure occurring within 24-72 hrs of exposure to RCM that cannot be attributed to other causes. It usually occurs in patients with preexisting renal impairment and diabetes. The mechanisms underlying CIN include reduction in medullary blood flow leading to hypoxia and direct tubule cell damage and the formation of reactive oxygen species. Identification of patients at high risk for CIN is important. We have reviewed the risk factors and procedures for prevention, providing a long list of references enabling readers a deep evaluation of them both. The first rule to follow in patients at risk of CIN undergoing radiographic procedure is monitoring renal function by measuring serum creatinine and calculating the eGFR before and once daily for 5 days after the procedure. It is advised to discontinue potentially nephrotoxic medications, to choose radiocontrast media at lowest dosage, and to encourage oral or intravenous hydration. In high-risk patients N-acetylcysteine may also be given.

Challenges and advances in the treatment of AKI

Treating or preventing AKI requires treating or preventing a rise in serum creatinine as well as the immediate and remote clinical consequences associated with AKI. Because a substantial number of patients with AKI progress to ESRD, identifying patients likely to progress and halting progression are important goals for treating AKI. Many therapies for AKI are being developed, including RenalGuard Therapy, which aims to maintain high urine output; α-melanocyte-stimulating hormone, with anti-inflammatory and antiapoptotic activities; alkaline phosphatase, which detoxifies proinflammatory substances; novel, small interfering RNA, directed at p53 activation; THR-184, a peptide agonist of bone morphogenetic proteins; removal of catalytic iron, important in free-radical formation; and cell-based therapies, including mesenchymal stem cells in vivo and renal cell therapy in situ. In this review, we explore what treatment of AKI really means, discuss the emerging therapies, and examine the windows of opportunity for treating AKI. Finally, we provide suggestions for accelerating the pathways toward preventing and treating AKI, such as establishing an AKI network, implementing models of catalytic philanthropy, and directing a small percentage of the Medicare ESRD budget for developing therapies to prevent and treat AKI and halt progression of CKD.

Effect of remote ischaemic conditioning on contrast-induced nephropathy in patients undergoing elective coronary angiography (ERICCIN): rationale and study design of a randomised single-centre, double-blind placebo-controlled trial

Background

Contrast-induced nephropathy (CIN), an acute kidney injury resulting from the administration of intravascular iodinated contrast media, is an important cause of morbidity/mortality following coronary angiographic procedures in high-risk patients. Despite preventative measures intended to mitigate the risk of CIN, there remains a need for an effective intervention. Remote ischaemic conditioning (RIC), where non-injurious ischaemia is applied to an arm prior to the administration of contrast, has shown promise in attenuating CIN but its effectiveness in preserving long-term renal function is unknown, which will be studied as part of the effect of remote ischaemic conditioning against contrast-induced nephropathy (ERICCIN) trial. (http://Controlled-trials.com Identifier: ISRCTN49645414.)

Methods

The ERICCIN trial is a single-centre, randomised double-blinded placebo-controlled trial which plans to recruit 362 patients who are at risk of CIN, defined by pre-existent renal impairment (estimated glomerular filtration rate <60 ml/min/1.73 m²), over a period of 2 years. Patients will be randomised to either control or RIC consisting of 4, 5 min 200 mmHg balloon-cuff inflation/deflations, to the upper arm. The primary endpoint will be the development of CIN (>25 % of eGFR, or rise of creatinine of >44 μmol/l) at 48 h. A key secondary endpoint will be whether RIC impacts upon persistent renal impairment over the 3-month follow-up period. Additional secondary endpoints include the measurement of serum neutrophil gelatinase-associated lipocalin and urinary albumin at 6, 48 h and 3 months following administration of contrast.

Implications

Findings from ERICCIN trial will potentially demonstrate that RIC attenuates contrast-induced acute and chronic kidney injury and influence future clinical practice guidelines in at-risk patients undergoing coronary angiographic procedures.