Contrast-induced nephropathy

A simple proteinuria-based risk score predicts contrast-associated acute kidney injury after percutaneous coronary intervention

Contrast-associated acute kidney injury (CA-AKI) is a complication of percutaneous coronary intervention (PCI). Because proteinuria is a sentinel marker of renal dysfunction, we assessed its role in predicting CA-AKI in patients undergoing PCI. A total of 1,254 patients undergoing PCI were randomly assigned to a derivation (n = 840) and validation (n = 414) dataset. We identified the independent predictors of CA-AKI where CA-AKI was defined by the new criteria issued in 2020, by a multivariate logistic regression in the derivation dataset. We created a risk score from the remaining predictors. The discrimination and calibration of the risk score in the validation dataset were assessed by the area under the receiver-operating characteristic curves (AUC) and Hosmer–Lemeshow test, respectively. A total of 64 (5.1%) patients developed CA-AKI. The 3 variables of the risk score were emergency procedures, serum creatinine, and proteinuria, which were assigned 1 point each based on the correlation coefficient. The risk score demonstrated a good discriminative power (AUC 0.789, 95% CI 0.766–0.912) and significant calibration. It was strongly associated with the onset of CA-AKI (Cochran-Armitage test, p < 0.0001). Our risk score that included proteinuria was simple to obtain and calculate, and may be useful in assessing the CA-AKI risk before PCI.

Contrast Media Volume to Creatinine Clearance Ratio in Predicting Nephropathy in Patients Undergoing Percutaneous Coronary Intervention: A Systematic Review and Meta-Analysis

The studies investigated the predictive value of the contrast media volume to creatinine clearance ratio (V/CrCl) for contrast-induced nephropathy (CIN) after a percutaneous coronary intervention (PCI) showed conflicting results and different cut-off values. The objective is to evaluate V/CrCl in the prediction of CIN after PCI. PubMed, Embase, and the Cochrane library were searched for eligible studies published from inception to November 2020. The optimal cut-off points of V/CrCl for predicting CIN were examined using odds ratios (ORs) and 95% confidence intervals (CIs). The random-effect model was used for analyses. Six studies (8 datasets, 16 899 patients) were included. V/CrCl was associated with CIN (OR = 2.67, 95% CI: 1.88-3.78, P < .001; I² = 79.3%, P_{heterogeneity} < .001). V/CrCl was associated with CIN in Asians (OR = 2.13, 95% CI: 1.52-2.98, P = .022; I² = 68.8%, P_{heterogeneity} < .001) and Europeans (OR = 3.87, 95% CI: 1.77-8.45, P < .001; I² = 85.1%, P_{heterogeneity} = .001). The association between V/CrCl and CIN was observed in the prospective cohort studies (OR = 2.16, 95% CI: 1.42-3.29, P = .009; I² = 78.9%, P_{heterogeneity} < .001) and retrospective cohort studies (OR = 3.31, 95% CI: 1.82-6.02, P < .001; I² = 80.6%, P_{heterogeneity} < .001). The sensitivity analysis showed the results were robust. V/CrCl is independently associated with an increased risk of CIN. V/CrCl could be considered a reliable predictor for the development of CIN in patients undergoing PCI.

Prevalence and Risk Factors for Acute Kidney Injury Among Adults Undergoing Cardiac Interventions in King Abdulaziz University Hospital: A Retrospective Review

Background

Acute kidney injury (AKI) is a syndrome that has been receiving considerable attention as a common risk in cardiac surgeries, which has consequences for short- and long-term survival implications, even for those who do not progress to renal failure. There have been limited studies in the Middle East, and specifically in the Kingdom of Saudi Arabia (KSA). Therefore, our study aimed to identify the prevalence of and risk factors for AKIs following adult cardiac interventions during 2010-2020 at the King Abdulaziz University Hospital (KAUH), Jeddah, Saudi Arabia.

Methods

Setting and Design: A retrospective medical record review was conducted among all the adult patients who underwent cardiac interventions and developed AKIs between 2010 and 2020. Google forms were used to extract the data from the hospital records. About statistical analysis binary logistic regression analyses, relative risks (RRs), and confidence intervals (CI) were used to determine the associations among the variables.

Results

After applying the inclusion and exclusion criteria, 564 patients were included. Their baseline demographic, clinical, biological, and operative characteristics were analyzed. AKIs developed in 110 (19.5%) patients and patients with diabetes were more likely to develop AKIs (P < 0.012, RR = 2.280, CI = 1.198-4.339). Hypertension showed a strong effect in the development of AKIs (P < 0.004, RR = 2.865, CI = 1.391-5.900). Moreover, patients who suffered from chronic heart failure were more prone to the development of AKIs (P < 0.008, RR = 4.189, CI =1.452-12.087). Furthermore, anemia with significant P-values (<0.002), and CIs of 1.509-6.822, indicated that these patients were more likely to develop AKIs (3.209 times).

Conclusion

We demonstrated that AKIs are frequent complications in adults after cardiac interventions and were associated with poor outcomes. Risk factors for the development of AKIs were identified to be diabetes mellitus, hypertension, chronic heart failure, and anemia. Further investigation of this cohort is necessary to better understand the problem of kidney injuries.

Impact of 719Trp>Arg Polymorphism of KIF 6 Gene on Contrast Induced Nephropathy in Patients Undergoing Coronary Angiography or Percutaneous Coronary Intervention

Background:

The identification of preventive strategies, such as statin therapy, is crucial for the management of contrast-induced nephropathy (CIN). Several studies showed the association between KIF6 polymorphism (replacement of Trp719 with Arg) and an increased cardiovascular risk, while others showed a correlation between ‘pleiotropic’ effects of statins and a reduction in cardiovascular events in the population with the risk allele due to the documented modulation of response to statin by KIF6 polymorphism. Aim of this study is to assess the impact of KIF6 polymorphism on the development of CIN.

Methods:

We analysed 1253 consecutive patients undergoing coronary angiography/PCI. Serum creatinine was collected at baseline, 24 and 48 hours after contrast exposure. We identified the different allelic patterns and assessed the incidence of CIN (absolute increase of 0.5mg/dL or relative >25% in creatinine at 24 and 48h).

Results:

KIF6 Arg mutation was found in 669 patients (heterozygotes n = 525, homozygotes n = 144). The total prevalence of CIN was 12.5% and we did not find any association between KIF6 polymorphism and CIN development (11.3%, 13.7%, 13.2% p = 0.30). At subgroups analysis among statin ‘naïve’ patients we found a higher prevalence of CIN in homozygous patients as compared to wild-type (20.7% vs 11.3%, p = 0.05), while opposite results were observed among patients with statin therapy (8.6% vs 13.2%, p = 0.28).

Conclusion:

KIF6 homozygous Arg was associated with a significant increase in the risk of CIN only among statin naive patients. Future studies are needed to evaluate the beneficial effects of statin especially in this subset of patients.

Alterations of Serum Biochemical and Urinary Parameters in a Canine Population before and after Intravenous Contrast Administration

Intravenous iodinated contrast (IVIC) medium is routinely administered to dogs. Scattered information exists regarding the serum biochemical or urinary profiles associated with the administration of IVIC in dogs. The aim of the study was to describe, compare, and discuss from the perspective of previous studies the alterations in serum biochemical and urinary parameters before (T0) and within one week (T1) of the IVIC administration during routine computed tomography (CT) scan evaluation of 22 dogs. Mature dogs presenting for CT scan evaluation for preoperative oncology staging/surgical planning were included. T1 evaluation was performed within one week of IVIC administration. Statistically significant differences in serum total protein, albumin, chloride, calcium, and phosphorus concentrations, urine protein to creatinine ratio, and urine specific gravity were found between T1 and T0. At T1, the serum creatinine concentration was within reference ranges in all dogs but one. An increase in the urine protein to creatinine ratio was observed in four samples, one of which was non-proteinuric at T0. Changes in biochemistry and urine parameters between T0 and T1 were not considered clinically significant.

Significance of serum FGF-23 for risk assessment of contrast-associated acute kidney injury and clinical outcomes in patients undergoing coronary angiography

Background

Fibroblast growth factor (FGF)-23 levels rise as kidney function declines. Whether elevated FGF-23 levels are associated with an increased risk for contrast-associated acute kidney injury (CA-AKI) and major adverse cardiovascular events (MACE) in patients undergoing coronary angiography remain uncertain.

Methods

In total, 492 patients receiving coronary angiography were enrolled. Their serum FGF-23 levels were measured before administration of contrast media. The occurrence of CA-AKI was defined as a rise in serum creatinine of 0.5 mg/dL or a 25% increase from the baseline value within 48 h after the procedure. All patients were followed up for at least 1 year or until the occurrence of MACE including death, nonfatal myocardial infarction (MI), and ischemic stroke.

Results

Overall, CA-AKI occurred in 41 (8.3%) patients. During a median follow-up of 2.6 years, there were 24 deaths, 3 nonfatal MIs, and 7 ischemic strokes. Compared with those in the lowest FGF-23 tertile, individuals in the highest FGF-23 tertile had a significantly higher incidence of CA-AKI (P < 0.001) and lower incidence of MACE-free survival (P = 0.001). In multivariate regression analysis, higher FGF-23 level was found to be independently associated with a graded risk for CA-AKI (OR per doubling, 1.90; 95% CI 1.48–2.44) and MACE (HR per doubling, 1.25; 95% CI 1.02–1.52).

Conclusions

Elevated FGF-23 levels were associated with an increased risk for CA-AKI and future MACE among patients undergoing coronary angiography. FGF-23 may play a role in early diagnosis of CA-AKI and predicting clinical outcomes after coronary angiography.

Contrast-induced nephropathy in non-cardiac vascular procedures, a narrative review: Part 1

Contrast-induced nephropathy (CIN) is an important complication of iodinated contrast medium (CM) administration, which is associated with both short- and long-term adverse outcomes (e.g., cardiorenal events, longer hospital stay, and mortality). CIN has been mainly studied in relation to cardiac procedures, but it can also occur following non-cardiac vascular interventions. This is Part 1 of a narrative review summarizing the available literature on CIN after non-cardiac vascular diagnostic or therapeutic procedures for aortic aneurysm and carotid stenosis. We discuss the definition, pathophysiology, incidence, risk factors, biomarkers, and consequences of CIN in these settings, as well as preventive strategies and alternatives to limit iodinated CM use. Physicians and vascular surgeons should be aware of CM-related adverse events and the potential strategies to avoid them. Clearly, more research in this important field is required.

Risk factors of contrast-induced nephropathy after percutaneous coronary intervention: a retrospective analysis

Objective

Contrast-induced nephropathy (CIN) is a serious complication in patients with acute coronary syndrome (ACS) and percutaneous coronary intervention (PCI). This study aimed to analyze the potential risk factors for CIN in patients undergoing PCI.

Methods

Patients with ACS who underwent PCI treatment from January 2017 to January 2020 were selected. The patients’ characteristics and medical information were collected and compared.

Results

A total of 1331 patients undergoing PCI were included. The incidence of CIN was 15.33%. Logistic regression analyses showed that a left ventricular ejection fraction ≤45% (odds ratio [OR] 4.18, 95% confidence interval [CI] 1.10–7.36), serum creatinine levels ≤60 μmol/L (OR 3.03, 95% CI 1.21–5.57), age ≥65 years (OR 2.75, 95% CI 1.32–4.60), log N-terminal pro-B-type natriuretic peptide levels ≥2.5 pg/mL (OR 2.31, 95% CI 1.18–5.13), uric acid levels ≥350 μmol/L (OR 2.29, 95% CI 1.04–5.30), emergency percutaneous intervention (OR 1.35, 95% CI 0.34–3.12), and triglyceride levels ≤1.30 mmol/L (OR 1.10, 95% CI 0.01–2.27) were independent risk factors for CIN in patients who underwent PCI.

Conclusions

Early prevention is required to reduce the occurrence of CIN in patients who undergo PCI and have risk factors for CIN.

Is there any association between contrast-induced nephropathy and serum uric acid levels?

Introduction: During the recent years, several studies have investigated that hyperuricemia is associated with greater incidence of contrast induced nephropathy (CIN). Most of them are in acute conditions like primary percutaneous coronary interventions. This study aimed to assess the relationship between high serum uric acid and incidence of acute kidney injury in patients undergoing elective angiography and angioplasty.

Methods: This prospective study was conducted on 211 patients who were admitted to hospital for elective coronary angiography or angioplasty. The researchers measured serum creatinine and uric acid on admission and repeated creatinine measurement in 48 hours and seven days after the procedure. According to serum uric acid, the patients were divided into two groups; group 1 with normal uric acid and group 2 with hyperuricemia which was defined as uric acid more than 6 mg/dL in women and 7 mg/dL in men. CIN is defined as an increased creatinine level of more than 0.5 mg/dL or 25% from the baseline in 48 hours after the intervention.

Results: In total, 211 patients with mean age of 60.58 years were enrolled in the study. Of these, 87 (41.2%) patients were in the high uric acid group and 124 (58.8%) were in the normal uric acid group. CIN was occurred in 16 patients (7.5%). Seven out of 16 (8.04%) were in the high uric acid and nine (7.2%) were in the normal uric acid group. There were no significant differences between the two groups (P =0.831).

Conclusion: The frequency of CIN development was not different in the patients with hyperuricemia.

Impact of creatinine screening on contrast-induced nephropathy following computerized tomography for stroke

OBJECTIVE

This study sought to evaluate rates of acute kidney injury in patients undergoing contrast-enhanced computerized tomography for acute stroke in the emergency department (ED) before and after the cessation of creatinine screening.

METHODS

This retrospective study compared ED patients receiving contrast-enhanced imaging for suspected acute stroke with and without protocolized creatinine screening. The primary outcome was CIN, defined as an increase in serum creatinine of 0.3 mg/dl within 48 hours or 50% above baseline within 7 days after contrast administration. Secondary outcomes consisted of CIN based on other definitions, renal impairment greater than 30 days from contrast administration, hemodialysis, and mortality. Outcomes were compared using difference of proportions and odds ratios with 95% confidence intervals.

RESULTS

This study included 382 subjects, with 186 and 196 in the screening and post-screening cohorts, respectively. No significant differences were observed for CIN (7.0% vs 7.1%, difference 0.1% [95% CI -5.6-5.1%], OR 1.02 [95% CI 0.47-2.24]), renal impairment greater than 30 days post-contrast (8.4% vs 7.5%, OR 0.88 [0.38-2.07]), or mortality (index visit: 4.8% vs 2.6%, OR 0.51 [0.17-1.57], 90-day follow-up: 6.7% vs 4.0%, OR 0.58 [0.22-1.53]). No patients from either group required hemodialysis.

CONCLUSIONS

The elimination of creatinine screening prior to obtaining contrast-enhanced computerized tomography in patients with suspected acute stroke did not adversely affect rates of CIN, hemodialysis, or mortality at a comprehensive stroke center.

Ferrotoxicity and its amelioration by endogenous vitamin D in experimental acute kidney injury

This work provides in-depth insights on catalytic iron-induced cytotoxicity and the resultant triggering of endogenous vitamin D synthesis in experimental acute kidney injury. Our results reveal significantly elevated levels of catalytic iron culminating in oxidant-mediated renal injury and a concomitant increase in 1,25-dihdyroxyvitamin D3 levels. Also, changes in other iron-related proteins including transferrin, ferritin, and hepcidin were observed both in the serum as well as in their mRNA expression. We consider all these findings vital since no connection between catalytic iron and vitamin D has been established so far. Furthermore, we believe that this work provides new and interesting results, with catalytic iron emerging as an important target in ameliorating renal cellular injury, possibly by timely administration of vitamin D. It also needs to be seen if these observations made in rats could be translated to humans by means of robust clinical trials.

Ferrotoxicity and its amelioration by endogenous vitamin D in experimental acute kidney injury

Acute kidney injury causes significant morbidity and mortality. This experimental animal study investigated the simultaneous impact of iron and vitamin D on acute kidney injury induced by iohexol, an iodinated, non-ionic monomeric radiocontrast agent in Wistar rats. Out of 36 healthy male Wistar rats, saline was injected into six control rats (group 1) and iohexol into the remaining 30 experimental rats (groups 2 to 6 comprising six rats each). Biochemical, renal histological changes, and gene expression of iron-regulating proteins and 1 α-hydroxylase were analyzed. Urinary neutrophil gelatinase-associated lipocalin (NGAL), serum creatinine, urine protein, serum and urine catalytic iron, 25-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3, and tissue lipid peroxidation were assayed. Rats injected with iohexol showed elevated urinary NGAL (11.94 ± 6.79 ng/mL), serum creatinine (2.92 ± 0.91 mg/dL), and urinary protein levels (11.03 ± 9.68 mg/mg creatinine) together with histological evidence of tubular injury and iron accumulation. Gene expression of iron-regulating proteins and 1 α-hydroxylase was altered. Serum and urine catalytic iron levels were elevated (0.57 ± 0.17; 48.95 ± 29.13 µmol/L) compared to controls (0.49 ± 0.04; 20.7 ± 2.62 µmol/L, P < 0.001). Urine catalytic iron positively correlated with tissue peroxidation (r = 0.469, CI 0.122 to 0.667, P = 0.004) and urinary NGAL (r = 0.788, CI 0.620 to 0.887, P < 0.001). 25-hydroxyvitamin D3 (61.58 ± 9.60 ng/mL) and 1,25-dihydroxyvitamin D3 (50.44 ± 19.76 pg/mL) levels increased simultaneously. In a multivariate linear regression analysis, serum iron, urine catalytic iron, and tissue lipid peroxidation independently and positively predicted urinary NGAL, an acute kidney injury biomarker. This study highlights the nephrotoxic potential of catalytic iron besides demonstrating a concurrent induction of vitamin D endogenously for possible renoprotection in acute kidney injury.

Impact statement

This work provides in-depth insights on catalytic iron-induced cytotoxicity and the resultant triggering of endogenous vitamin D synthesis in experimental acute kidney injury. Our results reveal significantly elevated levels of catalytic iron culminating in oxidant-mediated renal injury and a concomitant increase in 1,25-dihdyroxyvitamin D3 levels. Also, changes in other iron-related proteins including transferrin, ferritin, and hepcidin were observed both in the serum as well as in their mRNA expression. We consider all these findings vital since no connection between catalytic iron and vitamin D has been established so far. Furthermore, we believe that this work provides new and interesting results, with catalytic iron emerging as an important target in ameliorating renal cellular injury, possibly by timely administration of vitamin D. It also needs to be seen if these observations made in rats could be translated to humans by means of robust clinical trials.

Contrast-induced acute kidney injury

Although major advancements in the field of cardiology have allowed for an increasing number of patients to undergo minimally invasive imaging and interventional procedures, contrast-induced acute kidney injury (CI-AKI) continues to be a dreaded complication among patients receiving intravascular contrast media. CI-AKI is characterized by progressive decline in kidney function within a few days of contrast medium administration. Physiological changes resulting from the direct nephrotoxic effect of contrast media on tubular epithelial cells and release of vasoactive molecules have been implicated in creating a state of increased oxidative stress and subsequent ischemic renal cell injury. Over the last several years, preventive strategies involving intravenous hydration, pharmaceutical agents and renal replacement therapies have resulted in lower rates of CI-AKI. However, due to the evolving paradigm of diagnostic and therapeutic interventions, several unanswered questions remain. This review highlights the epidemiology, pathogenesis and preventive strategies of CI-AKI.

The conundrum of contrast-induced acute kidney injury

More than sixty years have elapsed since contrast induced nephropathy (CIN) was first described in the medical literature. This term has since been extensively explored, with a variety of studies conducted to investigate its incidence and various mechanisms examined to explain its pathophysiology. However, the topic of CIN remains one of controversy with a widely variable and often questionable incidence derived from various studies. The past two decades have seen a surge in reports questioning the existing of CIN altogether and if more harm is actually being caused to patients out of fear of this potential complication. We have attempted to review relevant studies regarding CIN and highlight the key points of its surmised understanding. The review has a higher focus on more recent literature and updates, in order to determine if an accurate estimate can be made on the incidence of CIN. While there was certainly no lack of material available, practically all the studies reviewed were limited by one or more significant drawbacks that limited the reliability of their conclusions regarding CIN. Based on the information reviewed, the strengths and the flaws encountered in other studies can be used to design a randomized control trial that may help in concluding the longstanding debate on this topic. However due to time, financial, and perhaps even ethical constraints such a trial will be difficult to arrange, and so a definitive answer on CI-AKI, and whether it really exist, may continue to elude clinicians.

Carbon dioxide-angiography for patients with peripheral arterial disease at risk of contrast-induced nephropathy

Patients with peripheral arterial disease (PAD) and critical limb ischemia are at risk for limb amputation and require urgent management to restore blood flow. Patients with PAD often have several comorbidities, including chronic kidney disease, diabetes mellitus, and hypertension. Diagnostic and interventional angiography using iodinated contrast agents provides excellent image resolution but can be associated with contrast-induced nephropathy (CIN). The use of carbon dioxide (CO₂) as a contrast agent reduces the volume of iodine contrast required for angiography and reduces the incidence of CIN. However, CO₂ angiography has been underutilized due to concerns regarding safety and image quality. Modern CO₂ delivery systems with advanced digital subtraction angiography techniques and hybrid angiography have improved imaging accuracy and reduced the incidence of CIN. Awareness of the need for optimal imaging conditions, contraindications, and potential complications have improved the safety of CO₂ angiography. This review aims to highlight current technological advances in the delivery of CO₂ in vascular angiography for patients with PAD and critical limb ischemia, which result in limb preservation while preventing kidney damage.

Impact of vascular access on the development of contrast induced nephropathy in patients undergoing coronary angiography and/or percutaneous coronary intervention

BACKGROUND

Contrast induced nephropathy (CIN) is a common complication of procedures that foresee the use of contrast media. Several risk factors have been identified as independent predictors of CIN, but, to date, no definitive data are available about the association between the angiographic approach and its development.

METHODS AND RESULTS

Our population included 4199 patients undergoing coronary angiography and/or PCI. CIN was defined as an absolute ≥0.5 mg/dl or a relative ≥25% increase in creatinine level at 24-48 h after the procedure without another clear cause for the acute kidney injury. The total incidence of CIN was 12.4%. We divided our population into two groups, according to the angiographic approach: transradial (TR) n = 1915 or transfemoral (TF) n = 2284. Patients treated with TR approach were more often males, with history of hypertension, and PCI, but less often diabetic, with previous myocardial infarction, coronary artery by-pass graft surgery and cerebrovascular accident. They had a higher ejection fraction, higher prevalence of PCI, elective indication but interestingly a lower amount of contrast volume. Patients treated with TR approach had higher platelets, Total, LDL and HDL cholesterol, but lower triglycerides, glycaemia and basal creatinine. No significant difference was observed between the two groups regarding the development of CIN (TR 13.2% vs TF 11.7%, p = 0.16). The absence of association between angiographic approach and the incidence of CIN was also confirmed at multivariate analysis after correction for baseline confounders (Adjusted OR [95% CI] = 1.2 [0.97-1.50], p = 0.09) and at subgroup analysis according to main risk factors for CIN. Similar results were obtained dividing our population according to propensity score tertiles: 1st Tertile CIN (TF 8.8% vs TR 8.9%), p = 0.95; OR (99% CI) = 1.01 (0.96-1.48), p = 0.95, 2nd Tertile CIN (TF 10.8% vs TR 12.4%), p = 0.35; OR (99% CI) = 1.17 (0.84-1.62), p = 0.35, and 3rd Tertile CIN (TF 15.6% vs TR 17.2%), p = 0.41; OR (99% CI) = 1.12 (0.85-1.48), p = 0.41.

CONCLUSION

This is the first large study showing the absence of relationship between the angiographic access and the incidence of CIN.

Metabolic Syndrome and the Iodine-Dose/Creatinine Clearance Ratio as Determinants of Contrast-Induced Acute Kidney Injury

BACKGROUND

Finding patients at risk of developing contrast-induced acute kidney injury (CI-AKI) is important because of its associated complications. In the present study, the contribution of different variables, such as the presence of metabolic syndrome (MetS), the volume creatinine clearance (V/CrCl) ratio, the iodine-dose (I-dose)/CrCl ratio, or hypertension, to CI-AKI was evaluated.

METHODS

A total of 255 patients undergoing elective coronary angiography with or without intervention were enrolled and divided into a MetS and a control group. All patients were assessed for the development of CI-AKI after the procedures.

RESULTS

CI-AKI occurred in 39.23% (51 of 130) of the MetS patients and 14.4% (18 of 125) of the control group (p < 0.001). The multivariable regression model showed that male sex and the use of statins decreased the risk of CI-AKI, and high triglyceride levels, I-dose/CrCl > 0.52, MetS, CrCl ≤60 mL/min, and age ≥70 years increased the risk of CI-AKI, independent of confounding factors. The difference in the mean V/CrCl ratio was statistically significant between patients who developed CI-AKI and those who did not show renal impairment (2.36 ± 1.35 vs. 1.43 ± 0.89, respectively; p < 0.001). The ROC curve analysis of I-dose/CrCl determined the best cutoff value for patients with and those without MetS as 0.51 and 0.63, with a sensitivity value of 68 and 72% and a specificity value of 73 and 74%, respectively.

CONCLUSIONS

We showed that MetS is a strong risk factor for CI-AKI in nondiabetic patients undergoing elective coronary interventions; and the I-dose/CrCl ratio is a strong predictor of CI-AKI in these patients. We suggest that clinicians identify MetS patients and calculate their I-dose/CrCl ratio before coronary interventions.

Prediction of contrast induced acute kidney injury using novel biomarkers following contrast coronary angiography

BACKGROUND/INTRODUCTION

Chronic kidney disease (CKD) is a risk factor for contrast induced acute kidney injury (CI-AKI). Contrast angiography in CKD patients is a common procedure. Creatinine is a delayed marker of CI-AKI and delays diagnosis which results in significant morbidity and mortality.

AIM

Early diagnosis of CI-AKI requires validated novel biomarkers.

DESIGN

A prospective observation study of 301 consecutive CKD patients undergoing coronary angiography was performed.

METHODS

Samples for plasma neutrophil gelatinase-associated lipocalin (NGAL), serum liver fatty acid-binding protein (L-FABP), serum kidney injury marker 1, serum interleukin 18 and serum creatinine were taken at 0, 1, 2, 4, 6 and 48 h post-contrast. Urinary NGAL and urinary cystatin C were collected at 0, 6 and 48 h. Incidence of major adverse clinical events (MACE) was recorded at 1 year. CI-AKI was defined as an absolute delta rise in creatinine of ≥26.5 µmol/l or a 50% relative rise from baseline at 48 h following contrast.

RESULTS

CI-AKI occurred in 28 (9.3%) patients. Plasma NGAL was most predictive of CI-AKI at 6 h. L-FABP performed best at 4 h. A combination of Mehran score > 10, 4 h L-FABP and 6 h NGAL improved specificity to 96.7%. MACE was statistically higher at 1 year in CI-AKI patients (25.0 vs. 6.2% in non-CI-AKI patients).

DISCUSSION/CONCLUSION

Mehran risk score, 4 h serum L-FAPB and 6 h plasma NGAL performed best at early CI-AKI prediction. CI-AKI patients were four times more likely to develop MACE and had a trebling of mortality risk at 1 year.

Improving Outcomes from Acute Kidney Injury (AKI): Report on an Initiative

Acute Kidney Injury (AKI) is a complex disorder for which currently there is no accepted definition. We describe an initiative to develop uniform standards for defining and classifying AKI and establish a forum for multidisciplinary interaction to improve care for patients with, or at risk for AKI. Members representing key societies in critical care and nephrology along with additional experts in adult and pediatric AKI participated in a 2-day conference in Amsterdam in September 2005 to draft consensus recommendations for diagnosing and staging AKI. This report describes the proposed diagnostic and staging criteria for AKI and the formation of a multidisciplinary collaborative network (Acute Kidney Injury Network (AKIN) focused on improving outcomes from AKI.

Association Between Acute Kidney Disease and Intravenous Dye Administration in Patients With Acute Stroke: A Population-Based Study

BACKGROUND AND PURPOSE

Computed tomographic angiography and conventional angiography provide timely vascular anatomic information in patients with stroke. However, iodinated contrast dye may cause acute kidney injury (AKI). Within a large, biracial population, we examined in-hospital incidence of new or worsening kidney disease in patients with stroke and its association with administration of intravenous dye.

METHODS

All adult residents of the Greater Cincinnati/Northern Kentucky region with acute ischemic stroke or intracerebral hemorrhage who presented to an emergency department in 2010 were included. Prevalence of unsuspected kidney disease at the time of emergency department presentation and the incidence of AKI after admission in 2 groups of patients-those who did and those who did not receive intravenous dye-were determined.

RESULTS

In 2010, 2299 patients met inclusion criteria (89% ischemic stroke and 11% intracerebral hemorrhage); mean age 69 years (SD 15), 22% black, and 54% women. Among these patients, 37% had kidney disease at baseline, including 22% (516/2299) in whom this was unsuspected. Two percent (2%; 15/853) of patients with baseline kidney disease developed AKI during the hospital stay. Of those with no baseline kidney disease, 1% (14/14 467) developed AKI. There was no association between dye administration and new or worsening kidney disease.

CONCLUSIONS

Although 22% of patients in the Greater Cincinnati/Northern Kentucky stroke population had unsuspected kidney disease, the incidence of new or worsening kidney disease was low, and AKI was not associated with dye administration. These findings confirm single-center reports that the risk of severe renal complications after contrast dye is small.

Gender Difference in the Risk of Contrast-Induced Nephropathy in Patients Undergoing Coronary Angiography or Percutaneous Coronary Intervention

Contrast-induced nephropathy (CIN) is a common complication of coronary angiography/percutaneous coronary intervention (PCI). Identification of high-risk patients and optimal periprocedural management are key points to reduce the incidence of this iatrogenic complication. We evaluated the impact of gender on CIN after coronary angiography/PCI. We enrolled 2851 consecutive patients (730 females and 1851 males) undergoing coronary angiography/PCI. Baseline clinical and procedural characteristics were collected according to gender. CIN was defined as an absolute ≥0.5mg/dL or a relative ≥25% increase in creatinine level 24 to 48 hours after the procedure. The incidence of CIN was 12.6% and was significantly higher among females (15.6% vs 11.4%, odds ratio (OR) [95% confidence interval (CI)] = 1.42 [1.11-1.82]; P = .004), but this result was not confirmed at multivariate analysis after correction for all baseline confounders (adjusted OR [95% CI] = 1.14 [0.81-1.60]; P = 0.45). In conclusion, we showed that female gender is associated with an increased risk of CIN after coronary angiography/PCI. However, this finding was not confirmed after correction for baseline confounders. Therefore, the higher risk profile rather than female gender itself may contribute to the higher occurrence of CIN among women.

Prevalence and Prognosis of Hyperkalemia in Patients with Acute Myocardial Infarction

BACKGROUND

Hyperkalemia is common and potentially dangerous in hospitalized patients; its contemporary prevalence and prognostic importance after acute myocardial infarction are not well described.

METHODS

In 38,689 consecutive patients with acute myocardial infarction from the Cerner Health Facts database, we evaluated the association between maximum in-hospital potassium levels and in-hospital mortality. Patients were stratified by dialysis status and grouped by maximum potassium as follows: <5 mEq/L, 5 to <5.5 mEq/L, 5.5 to <6.0 mEq/L, 6.0 to <6.5 mEq/L, and ≥6.5 mEq/L. Multivariable logistic regression was used to adjust for multiple patient and site characteristics. The relationship between the number of hyperkalemic values and the in-hospital mortality was evaluated.

RESULTS

Of 38,689 patients with acute myocardial infarction, 886 were on dialysis. The rate of hyperkalemia (maximum potassium ≥5.0 mEq/L) was 22.6% in patients on dialysis and 66.8% in patients not on dialysis. Moderate to severe hyperkalemia (maximum potassium ≥5.5 mEq/L) occurred in 9.8% of patients. There was a steep increase in mortality with higher maximum potassium levels. In-hospital mortality exceeded 15% once maximum potassium was ≥5.5 mEq/L regardless of dialysis status. The relationship between higher maximum potassium and increased mortality risk persisted after multivariable adjustment. In addition, patients with a greater number of hyperkalemic values (vs a single value) experienced higher in-hospital mortality.

CONCLUSIONS

Hyperkalemia is common in patients who are hospitalized with acute myocardial infarction. Higher maximum potassium levels and number of hyperkalemic events are associated with a steep mortality increase, with higher risks for adverse outcomes observed even at mild levels of hyperkalemia. Whether more intensive management of hyperkalemia may improve outcomes in patients with acute myocardial infarction merits further study.

Urinary NGAL-Positive Acute Kidney Injury and Poor Long-term Outcomes in Hospitalized Patients

Introduction

Neutrophil gelatinase−associated lipocalin (NGAL) is a widely studied biomarker of renal tubular injury. Urinary NGAL (uNGAL) during acute kidney injury (AKI) predicts short-term adverse outcomes. However, the long-term predictive value is unknown.

Methods

We performed a prospective observational study of 145 patients with hospital-acquired AKI according to Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE) criteria and analyzed the long-term predictive value of uNGAL at the time of AKI. We defined a composite outcome of all-cause mortality and the development of end-stage renal disease (ESRD).

Results

In all, 61 AKI patients died and 22 developed ESRD within 6 months. The uNGAL levels were significantly higher in patients with poor long-term outcomes. uNGAL levels ≥362 μg/l (highest quartile) and uNGAL levels between 95 and 362 μg/l (third quartile) were associated with hazard ratios of 3.7 (95% confidence interval, 2.1–6.5) and 1.9 (1.1–3.5), respectively, compared with uNGAL levels <95 μg/l (lower quartiles). After 6 months, 67% and 43% of patients within the highest and third uNGAL quartile, respectively, had either progressed to ESRD or died, compared to only 21% of patients with uNGAL in the lower 2 quartiles (P < 0.001). In multivariable Cox regression analyses accounting for conventional predictors, uNGAL was the strongest independent predictor of adverse long-term outcomes. The association of uNGAL levels and poor long-term outcomes remained significant in the subgroup of 107 AKI survivors discharged without requiring dialysis (P = 0.002).

Discussion

These data indicate that elevated uNGAL levels at AKI diagnosis predict poor long-term outcomes.

Novel Biomarkers of Acute Kidney Injury After Contrast Coronary Angiography

Acute kidney injury (AKI), defined as a rise in serum creatinine of greater than 25% from baseline measured at 48 hours after renal insult, may follow iodinated contrast coronary angiography. Termed contrast-induced nephropathy, it can result in considerable morbidity and mortality. Measurement of serum creatinine as a functional biomarker of glomerular filtration rate is widely used for detection of AKI, but it lacks sensitivity for the early diagnosis of AKI (typically rising 24 hours after functional loss) and, as a solely functional marker of glomerular filtration rate, is unable to differentiate among the various causes of AKI. These intrinsic limitations to creatinine measurement and the recognition that improved clinical outcomes are linked to a more timely diagnosis of AKI, has led investigators to search for novel biomarkers of "early" kidney injury. Several studies have investigated the utility of renal injury biomarkers in a variety of clinical settings including angiography/percutaneous coronary intervention, coronary artery bypass graft surgery, sepsis in intensive care patients, and pediatric cardiac surgery. In this article, we discuss the use of iodinated contrast for coronary procedures and the risk factors for contrast-induced nephropathy, followed by a review the potential diagnostic utility of several novel biomarkers of early AKI in the clinical settings of coronary angiography/percutaneous coronary intervention. In particular, we discuss neutrophil gelatinase associated lipocalin in depth. If validated, such biomarkers would facilitate earlier AKI diagnosis and improve clinical outcomes.

Impact of Iodinated Contrast on Renal Function and Hemodynamics in Rats with Chronic Hyperglycemia and Chronic Kidney Disease

Iodinated contrast (IC) is clinically used in diagnostic and interventional procedures, but its use can result in contrast-induced acute kidney injury (CI-AKI). Chronic kidney disease (CKD) and chronic hyperglycemia (CH) are important predisposing factors to CI-AKI. The aim of this study was to investigate the impact of iodinated contrast on the renal function and hemodynamics in rats with chronic hyperglycemia and chronic kidney disease. A total of 30 rats were divided into six groups; Sham: control of chronic renal disease; Citrate: control of chronic hyperglycemia (CH); Nx5/6: rats with 5/6 nephrectomy; Chronic Hyperglycemia: rats receiving Streptozotocin 65 mg/kg; Nx5/6 + IC: rats Nx5/6 received 6 mL/kg of IC; CH + IC: Chronic hyperglycemia rats receiving 6 mL/kg of IC. Renal function (inulin clearance; urinary neutrophil gelatinase-associated lipocalin, NGAL) and hemodynamics (arterial blood pressure; renal blood flow; renal vascular resistance) were evaluated. Iodinated contrast significantly increased urinary NGAL and reduced inulin clearance, while the hemodynamics parameters showed changes in arterial blood pressure, renal blood flow, and renal vascular resistance in both CKD and CH groups. The results suggest that the iodinated contrast in risk factors models has important impact on renal function and hemodynamics. NGAL was confirmed to play a role of highlight in diagnosis of CI-AKI.

Development of risk models for the prediction of new or worsening acute kidney injury on or during hospital admission: a cohort and nested study

Background

Acute kidney injury (AKI) is a common clinical problem with significant morbidity and mortality. All hospitalised patients are at risk. AKI is often preventable and reversible; however, the 2009 National Confidential Enquiry into Patient Outcome and Death highlighted systematic failings of identification and management, and recommended risk assessment of all emergency admissions.

Objectives

To develop three predictive models to stratify the risk of (1) AKI on arrival in hospital; (2) developing AKI during admission; and (3) worsening AKI if already present; and also to (4) develop a clinical algorithm for patients admitted to hospital and explore effective methods of delivery of this information at the point of care.

Study design

Quantitative methodology (1) to formulate predictive risk models and (2) to validate the models in both our population and a second population. Qualitative methodology to plan clinical decision support system (CDSS) development and effective integration into clinical care.

Settings and participants

Quantitative analysis – the study population comprised hospital admissions to three acute hospitals of East Kent Hospitals University NHS Foundation Trust in 2011, excluding maternity and elective admissions. For validation in a second population the study included hospital admissions to Medway NHS Foundation Trust. Qualitative analysis – the sample consisted of six renal consultants (interviews) and six outreach nurses (focus group), with representation from all sites.

Data collection

Data (comprising age, sex, comorbidities, hospital admission and outpatient history, relevant pathology tests, drug history, baseline creatinine and chronic kidney disease stage, proteinuria, operative procedures and microbiology) were collected from the hospital data warehouse and the pathology and surgical procedure databases.

Data analysis

Quantitative – both traditional and Bayesian regression methods were used. Traditional methods were performed using ordinal logistic regression with univariable analyses to inform the development of multivariable analyses. Backwards selection was used to retain only statistically significant variables in the final models. The models were validated using actual and predicted probabilities, an area under the receiver operating characteristic (AUROC) curve analysis and the Hosmer–Lemeshow test. Qualitative – content analysis was employed.

Main outcome measures

(1) A clinical pratice algorithm to guide clinical alerting and risk modeling for AKI in emergency hospital admissions; (2) identification of the key variables that are associated with the risk of AKI; (3) validated risk models for AKI in acute hospital admissions; and (4) a qualitative analysis providing guidance as to the best approach to the implementation of clinical alerting to highlight patients at risk of AKI in hospitals.

Findings

Quantitative – we have defined a clinical practice algorithm for risk assessment within the first 24 hours of hospital admission. Bayesian methodology enabled prediction of low risk but could not reliably identify high-risk patients. Traditional methods identified key variables, which predict AKI both on admission and at 72 hours post admission. Validation demonstrated an AUROC curve of 0.75 and 0.68, respectively. Predicting worsening AKI during admission was unsuccessful. Qualitative – analysis of AKI alerting gave valuable insights in terms of user friendliness, information availability, clinical communication and clinical responsibility, and has informed CDSS development.

Conclusions

This study provides valuable evidence of relationships between key variables and AKI. We have developed a clinical algorithm and risk models for risk assessment within the first 24 hours of hospital admission. However, the study has its limitations, and further analysis and testing, including continuous modelling, non-linear modelling and interaction exploration, may further refine the models. The qualitative study has highlighted the complexity regarding the implementation and delivery of alerting systems in clinical practice.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

Sodium bicarbonate prophylactic therapy in the prevention of contrast-induced nephropathy in patients admitted to the intensive care unit of a teaching hospital: a retrospective cohort study

Background

Intravenously administered iodine-containing contrast medium (CM) is associated with the development of contrast-induced nephropathy (CIN). Data on the effectiveness of sodium bicarbonate therapy in the prevention of CIN are controversial. Furthermore, the incidence of and risk factors for CIN in intensive care unit (ICU) patients are poorly defined. We investigated the effectiveness of sodium bicarbonate prophylaxis and the incidence of and risk factors for CIN in a heterogeneous ICU population.

Methods

This retrospective cohort study included patients admitted to the ICU in 2009–2011 who received CM for computed tomography (CT).

Results

Two hundred eleven CT scans with CM, performed in 170 patients, were included in the study. Contrast prophylaxis with sodium bicarbonate was administered in 48 of the 211 cases. CIN developed in 19 of the 48 cases receiving prophylaxis and in 39 of 163 cases not receiving prophylaxis (p = 0.03). In 115 CTs performed in patients with a glomerular filtration rate (GFR) >60 mL/min, prophylaxis was administered 15 times (13 %) and no prophylaxis was administered 100 times (87 %). CIN developed in 12 and 13 % of these cases, respectively (NS). In 96 CTs in patients with a GFR <60 mL/min, 17 of 33 (51.5 %) cases receiving prophylaxis developed CIN and 27 of 63 (42.9 %) cases not receiving prophylaxis developed CIN (NS). Prophylactic sodium bicarbonate therapy did not prevent CIN in our patients, irrespective of pre-existing renal failure. Pre-existing renal impairment (odds ratio 4.41), an elevated Acute Physiology and Chronic Health Evaluation (APACHE) IV score (odds ratio 1.02), and higher haemoglobin levels (odds ratio 0.64) were significant and independent risk factors associated with the development of CIN.

Conclusions

Prophylactic isotonic sodium bicarbonate was not associated with a decreased incidence of CIN in ICU patients. Current sodium bicarbonate prophylaxis guidelines cannot be generalized to a heterogeneous ICU population. Pre-existing renal impairment was associated with the highest CIN risk.

Nephroprotective potential of carnitine against glycerol and contrast-induced kidney injury in rats through modulation of oxidative stress, proinflammatory cytokines, and apoptosis

OBJECTIVE

Contrast media (CM) are a major cause of nephropathy in high-risk patients. The aim of this study was to examine the effects of carnitine (CAR) in advanced nephrotoxicity due to CM administration in rats with glycerol-induced renal functional disorder.

METHODS

40 rats were divided randomly into five groups (n = 8): (1) healthy group; (2) glycerol only (GLY); (3) glycerol and CM (GLY + CM); (4) glycerol, CM and 200 mg kg(-1) carnitine (CAR200, Carnitene(®); Sigma-tau/Santa Farma, Istanbul, Turkey); and (5) glycerol, CM and 400 mg kg(-1) carnitine (CAR400). Kidney injury was induced with a single-dose, intramuscular injection of 10 ml kg(-1) body weight (b.w.) of GLY. CAR was administered intraperitoneally. CM (8 ml kg(-1) b.w. iohexol, Omnipaque™; Opakim Medical Products, Istanbul, Turkey) was infused via the tail vein to the rats in Groups 3-5.

RESULTS

l-carnitine administration significantly decreased serum creatinine and blood urea nitrogen levels. Superoxide dismutase and glutathione activity increased significantly in the treatment groups compared with the nephrotoxic groups. CAR400 significantly reduced malondialdehyde levels to healthy levels. In the treatment groups, tumour necrosis factor (TNF)-α, transforming growth factor 1β, interleukin 1β and caspase-3 gene expression decreased compared with the nephrotoxic groups. TNF-α and nuclear factor kappa-beta (NF-κB) protein expression increased after CM and CAR administration reduced both TNF-α and NF-κB expressions. Histopathologically, hyaline and haemorrhagic casts and necrosis in proximal tubules increased in the nephrotoxicity groups and decreased in the CAR groups.

CONCLUSION

The results reveal that l-carnitine protects the oxidant/antioxidant balance and decreases proinflammatory cytokines and apoptosis in CM-induced nephrotoxicity in rats with underlying pathology.

ADVANCES IN KNOWLEDGE

Depending on the underlying kidney pathologies, the incidence of CM-induced nephropathy (CIN) increases. Therefore, this is the best model to represent clinically observed CIN.

Contrast volume to creatinine clearance ratio for the prediction of contrast-induced nephropathy in patients undergoing coronary angiography or percutaneous intervention

BACKGROUND

Contrast-induced nephropathy is a common complication of procedures that are likely to use contrast media. The identification of high-risk patients and preventive optimal hydration are key measures to reduce the incidence of contrast-induced nephropathy. The aim of this study was to evaluate the role of the contrast volume to creatinine clearance ratio (V/CrCl) in the prediction of contrast-induced nephropathy after coronary angiography or percutaneous coronary intervention.

METHODS

Our population consisted of 2308 consecutive patients undergoing coronary angiography and/or percutaneous coronary intervention. The risk of contrast-induced nephropathy was evaluated across quartiles of the V/CrCl. Receiver operating characteristic curves were used to identify the best predictive value. Contrast-induced nephropathy was defined as an absolute increase of 0.5 mg/dL or a relative increase of >25% in creatinine levels 24-48 hours after the procedure.

RESULTS

The total incidence of contrast-induced nephropathy was 12.2% and was significantly higher in the fourth quartile (first quartile 8.8%, second quartile 8.9%, third quartile 11.6% and fourth quartile 19.4%; P < 0.001). Using receiver operating characteristic curves we identified V/CrCl ≥ 6.15 as the best discriminant value for the prediction of contrast-induced nephropathy, which occurred in 25.1% of patients with V/CrCl ≥ 6.15 versus 9.7% in patients with V/CrCl < 6.15. These results were also confirmed at multivariate analysis after correction for all baseline confounders (adjusted odds ratio (AOR) (95% confidence interval (CI)) 1.81 (1.19-2.76); P = 0.005). The association between V/CrCl > 6.15 and an increased risk of contrast-induced nephropathy was confirmed among diabetic (11% vs. 27.7%; p P < 0.001) and non-diabetic patients (8.9% vs. 23%; Pp < 0.001), also after correction for all baseline confounders.

CONCLUSIONS

This is one of the largest studies evaluating the association between the V/CrCl ratio and the risk of contrast-induced nephropathy in patients undergoing coronary angiography or percutaneous coronary intervention. We found that a V/CrCl ratio >6.15 was independently associated with an increased risk of contrast-induced nephropathy.

Utility of the Logistic Clinical Syntax Score in the Prediction of Contrast-Induced Nephropathy After Primary Percutaneous Coronary Intervention

BACKGROUND

The Logistic Clinical Syntax Score (log CSS) is a combined risk scoring system that includes clinical and anatomic parameters; it has been found to be effective for the prediction of mortality in patients with ST-elevation myocardial infarction (STEMI). The aim of the present study was to assess whether the log CSS was associated with the development of contrast-induced nephropathy (CIN) in patients who underwent primary percutaneous coronary intervention (pPCI).

METHODS

A total of 930 patients with STEMI undergoing pPCI between January 2012 and August 2013 were included prospectively. The patients were grouped according to the development of CIN. Either an absolute serum creatinine level ≥ 0.5 mg/dL or a 25% increase in the serum creatinine level compared with the baseline level within 48 hours after the administration of contrast medium was defined as CIN.

RESULTS

The Synergy Between Percutaneous Coronary Interventions With Taxus and Cardiac Surgery score (SYNTAX [SS]) and log CSS were higher in patients with CIN than in those without. In the multivariate analysis, log CSS (odds ratio, 1.405, 95% confidence interval, 1.318-1.497; P < 0.001), hemoglobin, and contrast volume were found to be independent predictors of CIN. In the receiver operating characteristic analysis, a log CSS > 9.5 had a 74.5% sensitivity and a 90.5% specificity for predicting CIN, with an area under the curve (AUC) of 0.892, whereas an SS > 18.5 had a 64% sensitivity, a 58.1% specificity, and an AUC of 0.625 (0.892 vs 0.625; P < 0.001). A log CSS > 9.5 was associated with in-hospital and long-term mortality, reinfarction, revascularization, and in-hospital hemodialysis (P < 0.001 for each).

CONCLUSIONS

The log CSS may improve the accuracy of risk stratification for the development of CIN in patients undergoing pPCI.

Oral salt and water versus intravenous saline for the prevention of acute kidney injury following contrast-enhanced computed tomography: study protocol for a pilot randomized trial

Background

Although intravenous saline is the accepted prophylactic measure for the prevention of contrast- induced acute kidney injury, the oral route could offer an equivalent, practical, and cost saving approach. A systematic review of randomized trials that compared oral versus intravenous volume expansion for the prevention of radiocontrast-induced nephropathy in patients receiving arterial contrast reported no significant difference in the risk of contrast induced acute kidney injury between the oral and intravenous arms. Most trials for contrast nephropathy prevention have been in the setting of arterial contrast such as with cardiac catheterization, and not with venous contrast, such as computed tomography. The aim of this paper is to describe the protocol of a pilot trial comparing the effect of oral salt and water versus intravenous saline on the prevention of Acute Kidney Injury following contrast-enhanced computed tomography.

Methods

Our study is a pilot, single-centre parallel randomized controlled trial. To be included, participants must be at stage 4 of chronic kidney disease as defined by a glomerular filtration rate <30 mL/min/1.73 m², aged greater than 18 years and to undergo an outpatient contrast-enhanced computer tomography of the chest or abdomen. A total 50 patients will be randomised to receive either oral salt and water or intravenous isotonic saline. The primary outcome is feasibility, including estimates of recruitment rate, adherence to intervention and completeness of follow-up to assist in planning the definitive trial. The secondary outcome is safety and includes adverse events with oral salt and water loading as compared to intravenous isotonic saline.

Discussion

The results of this pilot trial will provide critical information to plan a definitive trial to test the efficacy of the route of volume loading regimens in prevention of acute kidney injury after contrast-enhanced CT scans.

Trial registration

The trial is registered at the US National Institutes of Health (ClinicalTrials.gov) # NCT02084771.

Proteinuria and Reduced Estimated Glomerular Filtration Rate Are Independent Risk Factors for Contrast-Induced Nephropathy After Cardiac Catheterization

BACKGROUND

The aim of this study was to investigate the incidence of contrast-induced nephropathy (CIN) according to renal function in patients with or without proteinuria after cardiac catheterization in Japan. METHODS AND RESULTS: We conducted a multicenter prospective observational study involving 27 hospitals from all over Japan, which enrolled 906 patients with cardiac catheterization. CIN was defined as increase in serum creatinine ≥0.5 mg/dl or ≥25% from baseline between 48 and 72 h after exposure to contrast. The incidence of CIN in patients with estimated glomerular filtration rate (eGFR) <30 ml/min/1.73 m²was significantly higher than that in patients with eGFR ≥60 ml/min/1.73 m². In patients without proteinuria, the incidence of CIN did not increase as eGFR decreased, but such a trend was observed in patients with proteinuria. Proteinuria was highly significantly associated with CIN in patients with eGFR 30-44 ml/min/1.73 m²(OR, 12.1; 95% CI: 2.81-82.8; P=0.0006) and eGFR <30 ml/min/1.73 m²(OR, 17.4; 95% CI: 3.32-321; P=0.0001). On multivariate logistic regression analysis, proteinuria (OR, 4.09; 95% CI: 1.66-10.0), eGFR (OR, 1.02; 95% CI: 1.00-1.04), contrast volume/eGFR (OR, 1.31; 95% CI: 1.04-1.65), and Ca antagonist use (OR, 3.79; 95% CI: 1.52-10.8) were significant predictors of CIN.

CONCLUSIONS

Proteinuria and reduced eGFR are independent risk factors for CIN after cardiac catheterization.

Urinary kidney injury molecule-1 as an early indicator to predict contrast-induced acute kidney injury in patients with diabetes mellitus undergoing percutaneous coronary intervention

With the improvement of the skill level of coronary intervention, contrast agents are used more widely. As a result, contrast-induced acute kidney injury (CI-AKI) is currently the third leading cause of hospital-acquired AKI. Traditionally, AKI is defined by measuring an increase of the serum creatinine concentration (Scr). CI-AKI indicates impairment in renal function, which is diagnosed as an elevation in the SCr levels following intravascular injection of the contrast media. However, Scr is an insensitive indicator for detecting CI-AKI. The present study was designed to investigate whether human urinary kidney injury molecule-1 (KIM-1) is an early marker to predict CI-AKI in patients with diabetes mellitus undergoing percutaneous coronary intervention (PCI). The present study includes the general clinical data of 145 patients with diabetes mellitus who underwent PCI between March 1, 2013 and December 31, 2013. A non-ionic, low osmolarity contrast agent was used during the present study. The Scr levels and estimated glomerular filtration rate were measured prior to and within 24 and 48 h after the injection of contrast agents. Urinary samples were collected prior to and within 2, 6, 12, 24 and 48 h after the coronary interventional procedure. Simultaneously, the urinary KIM-1 values were measured using an ELISA kit. CI-AKI was diagnosed as an increase of ≥0.5 mg/dl or ≥25% in Scr concentration over baseline, 24-48 h after the procedure. In total, 19 of 145 (13.1%) patients exhibited CI-AKI. There was a significant difference (P<0.05) between the urinary KIM-1 levels measured 2, 6, 12, 24 and 48 h after the procedure and those prior to the procedure in the CI-AKI group. There was no significant difference between the Scr values measured 24 h after the procedure and those prior to the procedure. Evidently, using KIM-1 values to predict CI-AKI was <24 h earlier compared to using Scr values. The area under the receiver operating characteristic curve of KIM-1 24 h after the procedure was 0.856 and the 95% confidence interval of the corresponding area was 0.782-0.929. When the pivotal point of CI-AKI diagnosis was 6,327.755 pg/ml, the specificity was 85.7% and the sensitivity was 73.7%. Univariate analysis showed that the Scr concentration was positively correlated with the urinary KIM-1 level during the time prior to the procedure and 24 and 48 h after the procedure. In conclusion, the urinary KIM-1 may be a potential indicator for the early diagnosis of CI-AKI.

Contrast-Induced Nephropathy: Identifying the Risks, Choosing the Right Agent, and Reviewing Effective Prevention and Management Methods

With the rise in the use of intravenous iodinated contrast media for both computed tomography scan and angiographic studies, there is a greater likelihood of complications. One of the most well-known adverse effects is contrast-induced media nephropathy, which is also called contrast-induced acute kidney injury. This is third most common cause of hospital acquired acute renal failure. It is associated with an increase in morbidity, mortality, and greater financial burden on healthcare system. Because of these factors, it is important for the radiologist to not only recognize risk factors, as well as the signs and symptoms, but also to know how to manage patients appropriately.

Association between Platelet-to-Lymphocyte Ratio and Contrast-Induced Nephropathy in Patients Undergoing Percutaneous Coronary Intervention for Acute Coronary Syndrome

OBJECTIVE

Contrast-induced nephropathy (CIN) is associated with significantly increased morbidity and mortality after percutaneous coronary intervention (PCI). Patients with acute coronary syndrome (ACS) are at higher risk of CIN. The platelet-to-lymphocyte ratio (PLR) is closely linked to inflammatory conditions. We hypothesized that PLR levels on admission can predict the development of CIN after PCI for ACS.

SUBJECTS AND METHODS

A total of 426 patients (mean age 63.17 ± 13.01 years, 61.2% males) with ACS undergoing PCI were enrolled in this study. Admission PLR levels were measured before PCI. Serum creatinine values were measured before and within 72 h after the administration of contrast agents. Patients were divided into 2 groups: the CIN group and the no-CIN group. CIN was defined as an increase in serum creatinine level of ≥0.5 mg/dl or 25% above baseline within 72 h after contrast administration.

RESULTS

CIN developed in 53 patients (15.9%). Baseline PLR was significantly higher in patients who developed CIN compared to those who did not (160.8 ± 29.7 and 135.1 ± 26.1, respectively; p < 0.001). Multivariate analyses found that PLR [odds ratio (OR) 3.453, 95% confidence interval (CI) 1.453-8.543; p = 0.004] and admission creatinine (OR 6.511, 95% CI 1.759-11.095; p = 0.002) were independent predictors of CIN.

CONCLUSIONS

The admission PLR level is an independent predictor of the development of CIN after PCI in ACS.

Uric acid levels and the risk of Contrast Induced Nephropathy in patients undergoing coronary angiography or PCI

BACKGROUND AND AIM

Contrast Induced Nephropathy (CIN) is a common complication of procedures that require the use of contrast media, and seems to be mediated by oxidative stress and reactive oxygen species generation. Hyperuricemia is characterized by inhibited nitric oxide system and enhanced synthesis of reactive oxygen species. However, few studies have so far investigated the association between hyperuricemia and CIN that is therefore the aim of the current study among patients undergoing coronary angiography or percutaneous intervention.

METHODS AND RESULTS

We analyzed a total of 1950 patients with Creatinine clearance <90 ml/min) undergoing elective or urgent coronary angiography and/or angioplasty. Patients were divided according to tertiles of baseline uric acid (Group 1, ≤ 5.5 mg/dL n = 653; Group 2, 5.6-7.0 mg/dL, n = 654; Group 3, ≥ 7.0 mg/dL, n = 643). CIN was defined as an absolute ≥ 0.5 mg/dl or a relative ≥ 25% increase in the serum creatinine level at 24 or 48 h after the procedure. Patients with higher uric acid levels were older, previous smokers, with higher prevalence of hypertension and diabetes, but with lower family history of CAD. They had more often history of a previous CABG and baseline renal dysfunction. Patients of the third Tertile had also higher levels of white blood cells, higher triglycerides and lower HDL-cholesterol and higher percentage of dilated cardiomyopathy/valvular disease as indication for angiography and consequently a lower prevalence of PCI. Patients with higher SUA were more often on therapy with ACE inhibitors and diuretics, but less often with statins, nitrate, ASA and Clopidogrel at admission. The occurrence of CIN was observed in 251 patients (12.9%), and was significantly associated with uric acid levels (12.3% in Group 1, 10.4% in Group 2 and 16.0% in Group 3; p = 0.04). Similar results were observed when the analysis was performed according to each tertiles values in both male and female gender. The association between elevated uric acid (≥ 7 mg/dl) and CIN was confirmed by multivariate analysis after correction for baseline confounding (Adjusted OR [95%CI] = 1.42 [1.04-1.93], p = 0.026). Similar results were observed across major subgroups of high-risk patients, such as patients with diabetes, female gender, renal failure, hypertension, and elderly.

CONCLUSIONS

This is the first large study showing that among patients undergoing coronary angiography or percutaneous interventions elevated uric acid level is independently associated with an increased risk of CIN.

Do acute elevations of serum creatinine in primary care engender an increased mortality risk?

Background

The significant impact Acute Kidney Injury (AKI) has on patient morbidity and mortality emphasizes the need for early recognition and effective treatment. AKI presenting to or occurring during hospitalisation has been widely studied but little is known about the incidence and outcomes of patients experiencing acute elevations in serum creatinine in the primary care setting where people are not subsequently admitted to hospital. The aim of this study was to define this incidence and explore its impact on mortality.

Methods

The study cohort was identified by using hospital data bases over a six month period.

Inclusion criteria: People with a serum creatinine request during the study period, 18 or over and not on renal replacement therapy.

The patients were stratified by a rise in serum creatinine corresponding to the Acute Kidney Injury Network (AKIN) criteria for comparison purposes. Descriptive and survival data were then analysed.

Ethical approval was granted from National Research Ethics Service (NRES) Committee South East Coast and from the National Information Governance Board.

Results

The total study population was 61,432. 57,300 subjects with ‘no AKI’, mean age 64.The number (mean age) of acute serum creatinine rises overall were, ‘AKI 1’ 3,798 (72), ‘AKI 2’ 232 (73), and ‘AKI 3’ 102 (68) which equates to an overall incidence of 14,192 pmp/year (adult). Unadjusted 30 day survival was 99.9% in subjects with ‘no AKI’, compared to 98.6%, 90.1% and 82.3% in those with ‘AKI 1’, ‘AKI 2’ and ‘AKI 3’ respectively. After multivariable analysis adjusting for age, gender, baseline kidney function and co-morbidity the odds ratio of 30 day mortality was 5.3 (95% CI 3.6, 7.7), 36.8 (95% CI 21.6, 62.7) and 123 (95% CI 64.8, 235) respectively, compared to those without acute serum creatinine rises as defined.

Conclusions

People who develop acute elevations of serum creatinine in primary care without being admitted to hospital have significantly worse outcomes than those with stable kidney function.

Systemic and renal hemodynamic effects of intra-arterial radiocontrast

Background

Decreased renal blood flow (RBF) and vasoconstriction are considered major mechanisms of contrast-induced acute kidney injury (CIAKI). To understand the severity and duration of such putative effects, we measured systemic and renal hemodynamics after intra-arterial radiocontrast administration. The subjects were six Merino ewes. The setting was a university-affiliated research institute. This is a randomized cross-over experimental study.

Methods

Transit-time flow probes were implanted on the pulmonary and left renal arteries 2 weeks before experimentation. We simulated percutaneous coronary intervention by administering five intra-arterial boluses of 0.5 mL/kg saline (control) or radiocontrast (iodixanol) to a total of 2.5 mL/kg over 1 h. Cardiac output (CO), heart rate, mean arterial pressure (MAP), RBF, renal vascular conductance (RVC), urine output (UO), creatinine clearance (CrCl), and fractional excretion of sodium (FENa) were measured.

Results

In the first 8 h after intra-arterial administration of radiocontrast, CO, total peripheral conductance (TPC), and heart rate (HR) increased compared with those after normal saline administration. Thereafter, CO and TPC were similar between the two groups, but HR remained higher with radiocontrast (p < 0.001). After a short (30 min) period of renal vasoconstriction with preserved RBF secondary to an associated increase in MAP, RBF and RVC showed an earlier and greater increase (vasodilatation) with radiocontrast (p < 0.001) and remained higher during the first 2 days. Radiocontrast initially increased urine output (p < 0.001) and FENa (p = 0.003). However, the overall daily urine output decreased in the radiocontrast-treated animals at 2 days (p < 0.001) and 3 days (p = 0.006). Creatinine clearance was not affected.

Conclusions

In healthy animals, intra-arterial radiocontrast increased RBF, induced renal vasodilatation, and caused a delayed period of oliguria. Our findings suggest that sustained reduction in RBF and renal vasoconstriction may not occur in normal large mammals after intra-arterial radiocontrast administration.

Pre-diabetes and the risk of contrast induced nephropathy in patients undergoing coronary angiography or percutaneous intervention

BACKGROUND

Contrast induced nephropathy (CIN) is a complication of coronary angiography/percutaneous intervention (PCI). It is known that diabetes is an independent risk factor for CIN, but we have no data regarding the association between CIN and glycemic levels in patients without diabetes. Aim of our study was to evaluate whether high level of glycated-haemoglobin in patients without diabetes is associated with an increased risk of CIN.

METHODS

A total of 1324 patients without diabetes, undergoing elective/urgent coronary angiography/angioplasty were divided according to quartiles of baseline glycated-haemoglobin. CIN was defined as an absolute ≥ 0.5mg/dL or a relative ≥ 25% increase in creatinine level at 24-48 h after the procedure.

RESULTS

Patients with elevated glycated-haemoglobin were older, with hypertension, metabolic syndromes, previous history of AMI, PCI and CABG. They had higher gycaemia, fasting-glycaemia and triglycerides but lower HDL-cholesterol. Patients with higher glycated-haemoglobin were more often on therapy with statins, diuretics and calcium-antagonist at admission, had higher basal, 24 and 48 h creatinine, lower creatinine clearance and lower ejection fraction. They had the highest incidence of PCI and contrast volume-eGFR rate. CIN occurred in 10.6% of patients with a linear association with glycated-haemoglobin (p=0.001). No relationship was found between glycaemia/fasting glycaemia at admission and CIN. The multivariate analysis confirmed the association between elevated glycated haemoglobin (above the median value 5.7%) and the risk of CIN after adjustment for baseline confounding factors (Adjusted OR [95% CI]=1.69 [1.14-2.51], p=0.009). In fact, the results were consistent in major high-risk subgroups.

CONCLUSION

This is the first study showing that among patients without diabetes undergoing coronary angiography/PCI elevated glycated-haemoglobin but not glucose levels is independently associated with the risk of CIN.

Sildenafil citrate for prophylaxis of nephropathy in an animal model of contrast-induced acute kidney injury

Contrast-induced acute kidney injury (CIAKI) is one of the commonest complications associated with contrast media (CM). Although the exact etiology of CIAKI remains unclear, one hypothesis involves vasoconstriction of afferent arterioles resulting in renal ischemia. Increased renal blood flow, therefore, might represent an attractive target for the treatment of CIAKI. In this study we evaluated the protective effects of the phosphodiesterase type 5 (PDE5) inhibitor, sildenafil citrate, in a rabbit model of CIAKI. New Zealand white rabbits were used due to their susceptibility to CIAKI. To evaluate the effects of sildenafil, the drug was administered before CM infusion and repeatedly throughout the remainder of the experiment (6 mg/kg, p.o.). Animals were sacrificed after 48 hours and kidneys were prepared for histological evaluation. Intravenous administration of CM produced marked kidney injury. Serum creatinine concentrations were elevated within two hours of the infusion and remained elevated for the duration of the experiment. Histological evaluation of the kidneys revealed significant tubular necrosis. The effects of the CM were dose dependent. Treatment with sildenafil was associated with lesser degree of histological injury, attenuation in markers of acute kidney injury (48 hour creatinine 1.54±0.21 versus 4.42±1.31 mg/dl, p<0.05) and reduction in electrolyte derangement (percent change in serum K⁺ at 48 hours 2.55±3.80% versus 15.53±4.47%, p<0.05; serum Na⁺ at 48 hours −0.14±0.26% versus −1.97±1.29%, p = 0.20). The results suggest a possible role for PDE5 inhibitors in the treatment of CIAKI and warrant further evaluation to determine the exact mechanism of protection.

Serum creatinine role in predicting outcome after cardiac surgery beyond acute kidney injury

Serum creatinine is still the most important determinant in the assessment of perioperative renal function and in the prediction of adverse outcome in cardiac surgery. Many biomarkers have been studied to date; still, there is no surrogate for serum creatinine measurement in clinical practice because it is feasible and inexpensive. High levels of serum creatinine and its equivalents have been the most important preoperative risk factor for postoperative renal injury. Moreover, creatinine is the mainstay in predicting risk models and risk factor reduction has enhanced its importance in outcome prediction. The future perspective is the development of new definitions and novel tools for the early diagnosis of acute kidney injury largely based on serum creatinine and a panel of novel biomarkers.

Urinary interleukin-18 as an early indicator to predict contrast-induced nephropathy in patients undergoing percutaneous coronary intervention

Contrast-induced nephropathy (CIN) is at present the third leading cause of hospital-acquired acute kidney injury (AKI). Traditionally, it is diagnosed by measuring an increase of the serum creatinine (SCr) concentration. However, SCr is an insensitive marker for detecting CIN. This study was designed to investigate whether human urinary interleukin-18 (IL-18) is early predictive marker for CIN following coronary interventional procedures. The general clinical data of 180 patients who underwent coronary interventional procedures at the Department of Cardiology, Affiliated Hospital of Xuzhou Medical College from March 1, 2012 to September 31, 2012 were collected. A nonionic, low osmolality contrast agent was used in the laboratory at this time. SCr values and estimated glomerular filtration rate (eGFR) were measured prior to and within 24 and 48 h after the administration of contrast agents. Urine samples were collected prior to and 2, 6, 12, 24 and 48 h after the coronary interventional procedure, and urinary IL-18 levels were measured using an ELISA kit. CIN was defined as an increase of ≥0.5 mg/dl or ≥25% in SCr concentration over baseline 24–48 h after the procedure. CIN occurred in 16 of 180 (8.9%) patients. The levels of urinary IL-18 measured 2 h after the procedure were increased in the CIN group, but the increase was not significant (P>0.05). There were significant differences (P<0.05) between the urinary IL-18 levels 6, 12, 24 and 48 h after the procedure and those before the procedure. No significant difference was identified between the SCr levels measured prior to and 24 h after the procedure. The area under the receiver operating characteristic (ROC) curve of urinary IL-18 12 h after the procedure was 0.811 and the 95% confidence interval of the area under the curve was 0.735–0.888. If the critical point of the diagnosis of CIN was 815.61 pg/ml, the sensitivity was 87.5% and the specificity was 62.2%. Univariate analysis indicated that the urinary IL-18 level was positively correlated with the SCr concentration pre- and postprocedure. In conclusion, urinary IL-18 may be a promising indicator for the early prediction of CIN.