No increase in Kidney Injury Molecule-1 and Neutrophil Gelatinase-Associated Lipocalin excretion following intravenous contrast enhanced-CT

Risk of Acute Kidney Injury Following IV Iodinated Contrast Media Exposure: 2023 Update, From the AJR Special Series on Contrast Media

Iodinated contrast material (ICM) has revolutionized the field of diagnostic radiology through improvements in diagnostic performance and the expansion of clinical indications for radiographic and CT examinations. Historically, nephrotoxicity was a feared complication of ICM use, thought to be associated with a significant risk of morbidity and mortality. Such fears often precluded the use of ICM in imaging evaluations, commonly at the expense of diagnostic performance and timely diagnosis. Over the past 20 years, the nephrotoxic risk of ICM has become a topic of debate, as more recent evidence from higher-quality studies now suggests that many cases of what was considered contrast-induced acute kidney injury (CI-AKI) likely were cases of mistaken causal attribution; most of these cases represented either acute kidney injury (AKI) caused by any of myriad other known factors that can adversely affect renal function and were coincidentally present at the time of contrast media exposure (termed "contrast-associated AKI" [CA-AKI]) or a manifestation of the normal variation in renal function that increases with worsening renal function. This Special Series Review discusses the current state of knowledge regarding CI-AKI and CA-AKI, including the incidence, risk factors, outcomes, and prophylactic strategies in the identification and management of these clinical conditions.

The relationship between perioperative serum albumin and contrast-induced acute kidney injury in patients after percutaneous coronary intervention

OBJECTIVE

Contrast-induced acute kidney injury (CI-AKI) is a common complication in patients undergoing percutaneous coronary intervention (PCI). Studies have shown that perioperative serum albumin levels may play a role in the occurrence of CI-AKI. In this study, we aimed to investigate the effect of perioperative serum albumin (delta albumin or &Alb) levels on the occurrence and long-term prognosis of CI-AKI patients after PCI.

METHODS

A total of 959 patients who underwent PCI between January 2017 and January 2019 were selected for this study. A receiver operating characteristic curve was used to determine the optimal cut-off value of the &Alb level for predicting CI-AKI after PCI. Patients were divided into two groups based on the optimal cut-off value: the high &Alb group (&Alb ≥ 4.55 g/L) and the control group (&Alb < 4.55 g/L). The incidences of CI-AKI and major adverse cardiac events (MACEs, including all-cause death, nonfatal myocardial infarction, and target vessel revascularization) were compared between the groups. Cox regression analysis was used to identify predictors of long-term prognosis after PCI.

RESULTS

Of the 959 patients, 147 (15.3%) developed CI-AKI after PCI. The CI-AKI group had a greater level of &Alb than did the non-CI-AKI group [(6.14 (3.90-9.10) versus 3.48 (4.31-6.57), P < 0.01)]. The incidence of CI-AKI in the high &Alb group was significantly greater than that in the low group (23.6% versus 8.3%, P < 0.01). After a 1-year follow-up, the incidence of MACEs was significantly greater in the high &Alb group than in the low group (18.6% versus 14.5%, P = 0.030). Cox regression analysis confirmed that CI-AKI was an independent predictor of MACEs at the 1-year follow-up (HR 1.43, 95% CI 1.04-1.96, P = 0.028). In addition, patients with low preoperative serum albumin levels had s significantly greater incidence of MACEs than did those with high preoperative serum albumin levels (23.2% versus 19.5%, P = 0.013).

CONCLUSION

In summary, high baseline &Alb levels are an independent risk factor for CI-AKI in patients after PCI. The occurrence of CI-AKI in the perioperative period is also an independent predictor of long-term prognosis after PCI. These findings highlight the importance of monitoring &Alb levels and taking steps to prevent CI-AKI in patients undergoing PCI.

Association between uric acid level and contrast-induced acute kidney injury in patients with type 2 diabetes mellitus after coronary angiography: a retrospective cohort study

BACKGROUND

This study assessed the predictive value of uric acid (UA) for contrast-induced acute kidney injury (CI-AKI) in patients with type 2 diabetes mellitus (T2DM) who underwent coronary angiography (CAG). A nomogram to aid in the prediction of CI-AKI was also developed and validated, and the construction of a prognostic nomogram combined with clinical features was attempted.

METHODS

This study retrospectively enrolled T2DM patients who underwent CAG between December 2019 and December 2020 at the Affiliated Zhongda Hospital of Southeast University. Multivariable logistic regression analysis was used for the analysis of clinical outcomes. Receiver operating characteristic (ROC) analyses were performed to determine the area under the ROC curve (AUC) and the cut-off points for continuous clinical data. The prediction accuracies of models for CI-AKI were estimated through Harrell's concordance indices (C-index). Nomograms of the prognostic models were plotted for individualized evaluations of CI-AKI in T2DM patients after CAG.

RESULTS

A total of 542 patients with T2DM who underwent CAG were included in this study. We found that a high UA level (≥ 425.5 µmol/L; OR = 6.303), BUN level (≥ 5.98 mmol/L; OR = 3.633), Scr level (≥ 88.5 µmol/L; OR = 2.926) and HbA1C level (≥ 7.05%; OR = 5.509) were independent factors for CI-AKI in T2DM patients after CAG. The nomogram model based on UA, BUN, Scr and HbA1C levels presented outstanding performance for CI-AKI prediction (C-index: 0.878). Decision curve analysis (DCA) showed good clinical applicability in predicting the incidence of CI-AKI in T2DM patients who underwent CAG.

CONCLUSION

High UA levels are associated with an increased incidence of CI-AKI in T2DM patients after CAG. The developed nomogram model has potential predictive value for CI-AKI and might serve as an economic and efficient prognostic tool in clinical practice.

Contrast associated nephropathy after intravenous administration: what is the magnitude of the problem?

Intravenous contrast media (CM) is often used in clinical practice to enhance CT scan imaging. For many years, contrast-induced nephropathy (CIN) was thought to be a common occurrence and to result in dire consequences. When treating patients with abnormal renal function, it is not unusual that clinicians postpone, cancel, or replace contrast-enhanced imaging with other, perhaps less informative tests. New studies however have challenged this paradigm and the true risk attributable to intravenous CM for the occurrence of CIN has become debatable. In this article, we review the latest relevant medical literature and aim to provide an evidence-based answer to questions surrounding the risk, outcomes, and potential mitigation strategies of CIN after intravenous CM administration.

A Combined microRNA and Chemokine Profile in Urine to Identify Rejection After Kidney Transplantation

Supplemental Digital Content is available in the text.

There is an unmet need for noninvasive tools for diagnosis of rejection after kidney transplantation. The aim of this study was to determine the discriminative value of a combined cellular and molecular biomarker platform in urine for the detection of rejection.

Biochemical Markers in the Prediction of Contrast-induced Acute Kidney Injury

For many years clinicians have been searching for "kidney troponin"- a simple diagnostic tool to assess the risk of acute kidney injury (AKI). Recently, the rise in the variety of contrast-related procedures (contrast computed tomography (CT), percutaneous coronary intervention (PCI) and angiography) has resulted in the increased number of contrast-induced acute kidney injuries (CI-AKI). CIAKI remains an important cause of overall mortality, prolonged hospitalisation and it increases the total costs of therapy. The consequences of kidney dysfunction affect the quality of life and they may lead to disability as well. Despite extensive worldwide research, there are no sensitive and reliable methods of CI-AKI prediction. Kidney Injury Molecule 1 (KIM-1) and Neutrophil Gelatinase Lipocalin (NGAL) have been considered as kidney-specific molecules. High concentrations of these substances before the implementation of contrast-related procedures have been suggested to enable the estimation of kidney vulnerability to CI-AKI and they seem to have the predictive potential for cardiovascular events and overall mortality. According to other authors, routine determination of known inflammation factors (e.g., CRP, WBC, and neutrophil count) may be helpful in the prediction of CIAKI. However, the results of clinical trials provide contrasting results. The pathomechanism of contrast- induced nephropathy remains unclear. Due to its prevalence, the evaluation of the risk of acute kidney injury remains a serious problem to be solved. This paper reviews pathophysiology and suggested optimal markers facilitating the prediction of contrast-induced acute kidney injury.

Effect of No Prehydration vs Sodium Bicarbonate Prehydration Prior to Contrast-Enhanced Computed Tomography in the Prevention of Postcontrast Acute Kidney Injury in Adults With Chronic Kidney Disease: The Kompas Randomized Clinical Trial

IMPORTANCE

Prevention of postcontrast acute kidney injury in patients with stage 3 chronic kidney disease (CKD) by means of prehydration has been standard care for years. However, evidence for the need for prehydration in this group is limited.

OBJECTIVE

To assess the renal safety of omitting prophylactic prehydration prior to iodine-based contrast media administration in patients with stage 3 CKD.

DESIGN, SETTING, AND PARTICIPANTS

The Kompas trial was a multicenter, noninferiority, randomized clinical trial conducted at 6 hospitals in the Netherlands in which 523 patients with stage 3 CKD were randomized in a 1:1 ratio to receive no prehydration or prehydration with 250 mL of 1.4% sodium bicarbonate administered in a 1-hour infusion before undergoing elective contrast-enhanced computed tomography from April 2013 through September 2016. Final follow-up was completed in September 2017. Data were analyzed from January 2018 to June 2019.

INTERVENTIONS

In total, 262 patients were allocated to the no prehydration group and 261 were allocated to receive prehydration. Analysis on the primary end point was available in 505 patients (96.6%).

MAIN OUTCOMES AND MEASURES

The primary end point was the mean relative increase in serum creatinine level 2 to 5 days after contrast administration compared with baseline (noninferiority margin of less than 10% increase in serum creatinine level). Secondary outcomes included the incidence of postcontrast acute kidney injury 2 to 5 days after contrast administration, mean relative increase in creatinine level 7 to 14 days after contrast administration, incidences of acute heart failure and renal failure requiring dialysis, and health care costs.

RESULTS

Of 554 patients randomized, 523 were included in the intention-to-treat analysis. The median (interquartile range) age was 74 (67-79) years; 336 (64.2%) were men and 187 (35.8%) were women. The mean (SD) relative increase in creatinine level 2 to 5 days after contrast administration compared with baseline was 3.0% (10.5) in the no prehydration group vs 3.5% (10.3) in the prehydration group (mean difference, 0.5; 95% CI, -1.3 to 2.3; P < .001 for noninferiority). Postcontrast acute kidney injury occurred in 11 patients (2.1%), including 7 of 262 (2.7%) in the no prehydration group and 4 of 261 (1.5%) in the prehydration group, which resulted in a relative risk of 1.7 (95% CI, 0.5-5.9; P = .36). None of the patients required dialysis or developed acute heart failure. Subgroup analyses showed no evidence of statistical interactions between treatment arms and predefined subgroups. Mean hydration costs were €119 (US $143.94) per patient in the prehydration group compared with €0 (US $0) in the no prehydration group (P < .001). Other health care costs were similar.

CONCLUSIONS AND RELEVANCE

Among patients with stage 3 CKD undergoing contrast-enhanced computed tomography, withholding prehydration did not compromise patient safety. The findings of this study support the option of not giving prehydration as a safe and cost-efficient measure.

TRIAL REGISTRATION

Netherlands Trial Register Identifier: NTR3764.

Differences in acute kidney injury ascertainment for clinical and preclinical studies

Background

Acute kidney injury (AKI) is a common clinical condition directly associated with adverse outcomes. Several AKI biomarkers have been discovered, but their use in clinical and preclinical studies has not been well examined. This study aims to investigate the differences between clinical and preclinical studies on AKI biomarkers.

Methods

We performed a systematic review of clinical and preclinical interventional studies that considered AKI biomarkers in enrollment criteria and/or outcome assessment and described the main differences according to their setting, the inclusion of biomarkers in the definition of AKI and the use of biomarkers as primary or secondary end points.

Results

In the 151 included studies (76 clinical, 75 preclinical), clinical studies have prevalently focused on cardiac surgery (38.1%) and contrast-associated AKI (17.1%), while the majority of preclinical studies have focused on ether ischemia-reperfusion injury or drug-induced AKI (42.6% each). A total of 57.8% of clinical studies defined AKI using the standard criteria and only 19.7% of these studies used AKI biomarkers in the definition of renal injury. Conversely, the majority of preclinical studies defined AKI according to the increase in serum creatinine and blood urea nitrogen, and 32% included biomarkers in that definition. The percentage of both clinical and preclinical studies with biomarkers as a primary end point has not significantly increased in the last 10 years; however, preclinical studies are more likely to use AKI biomarkers as a primary end point compared with clinical studies [odds ratio 2.31 (95% confidence interval 1.17-4.59); P  =  0.016].

Conclusion

Differences between clinical and preclinical studies are evident and may affect the translation of preclinical findings in the clinical setting.

Contrast-induced nephropathy: Basic concepts, pathophysiological implications and prevention strategies

Contrast-induced nephropathy (CIN) is reversible acute renal failure observed following administration of iodinated contrast media (CM) during angiographic or other medical procedures such as urography. There are various mechanisms through which CM develop their nephrotoxic effects, including oxidative stress and apoptosis. CIN is a real-life, albeit not very rare, entity. Exact pathophysiology remains obscure and no standard diagnostic criteria apply. The Acute Kidney Injury Network criteria was recently employed but its incidence/clinical significance warrants further clarification based on recent methodological advancements, because most published studies to date were contaminated by bias. The current study is a comprehensive review conducted to provide an overview of the basic concepts of CIN and summarize recent knowledge on its pathophysiology and the evidence supporting potential prevention strategies. CIN is expected to increase morbidity, hospital stay and mortality, while all patients scheduled to receive CM should undergo risk assessment for CIN and high-risk patients may be considered candidates for prevention strategies. The value of using compounds with antioxidant properties other than sodium bicarbonate, remains controversial, warranting further clinical investigation.

Regulatory B cells: Phenotype, function and role in transplantation

While B cells are traditionally known for their roles in antibody production, antigen presentation and cytokine production, recent studies have highlighted the existence of B cells with regulatory properties, which have been termed Bregs, analogous to regulatory T cells (Tregs). Bregs have been found to play a role in autoimmune disease, malignancies, infections, and may also be involved in solid organ transplantation. Their main mechanism of action is by promoting the development of Tregs while suppressing effector CD4⁺ and CD8⁺ T cells, primarily by IL-10 secretion. In the field of transplantation evidence for an active role of Bregs is scarce. While the presence of Bregs has been associated with improved graft survival and operational tolerance in kidney transplant recipients, these findings are not without controversy. Since the majority of fundamental research on Bregs has been performed in the fields in autoimmunity and infectious diseases, we will first focus on what these fields taught us on basic Breg biology, after which the relevance for the transplant setting is discussed.

Diagnostic Value of Urine Tissue Inhibitor of Metalloproteinase-2 and Insulin-Like Growth Factor-Binding Protein 7 for Acute Kidney Injury: A Meta-Analysis

Background

Tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin-like growth factor-binding protein-7 (IGFBP7) are both involved in renal tubular epithelial cell cycle arrest in acute kidney injury (AKI). Several recent studies showed that urine TIMP-2 times IGFBP7 ([TIMP-2]*[IGFBP7]) is a promising biomarker to predict AKI.

Methods

The aim of this meta-analysis was to assess the diagnostic value of urine [TIMP-2]*[IGFBP7] for early diagnosis of AKI. Relevant studies were retrieved from the PubMed, EMBASE, and Cochrane Library databases. The sensitivity and specificity were determined, and summary receiver operating characteristic (SROC) curves were constructed.

Results

Ten full-text prospective studies were included in this meta-analysis. The estimated sensitivity of urine [TIMP-2]*[IGFBP7] for the early diagnosis of AKI was 0.84 (95% CI = 0.80–0.88) and the specificity was 0.57 (95%CI = 0.55–0.60). The SROC analysis showed an area under the curve of 0.8813.

Limitation

The limited number of included studies, small sample size, unpublished negative results and language limitation might have affected the evaluation.

Conclusion

Urine [TIMP-2]*[IGFBP7] is a promising candidate for early detection of AKI, especially in ruling-out AKI. However, the potential of this biomarker should be validated in larger studies with a broader spectrum of clinical settings.