Epidemiology of AKI: Utilizing Large Databases to Determine the Burden of AKI

Regional variation in incidence and prognosis of acute kidney injury

BACKGROUND

Examining regional variation in acute kidney injury (AKI) and associated outcomes may reveal inequalities and possibilities for optimization of the quality of care. Using the Danish medical databases, we examined regional variation in the incidence, follow-up and prognosis of AKI in Denmark.

METHODS

Patients with one or more AKI episodes in 2017 were identified using population-based creatinine measurements covering all Danish residents. Crude and sex-and-age-standardized incidence rates of AKI were estimated using census statistics for each municipality. Adjusted hazard ratios (aHR) of chronic kidney disease (CKD), all-cause death, biochemical follow-up and outpatient contact with a nephrology department after AKI were estimated across geographical regions and categories of municipalities, accounting for differences in demographics, comorbidities, medication use, lifestyle and social factors, and baseline kidney function.

RESULTS

We identified 63 382 AKI episodes in 58 356 adults in 2017. The regional standardized AKI incidence rates ranged from 12.9 to 14.9 per 1000 person-years. Compared with the Capital Region of Denmark, the aHRs across regions ranged from 1.04 to 1.25 for CKD, from 0.97 to 1.04 for all-cause death, from 1.09 to 1.15 for biochemical follow-up and from 1.08 to 1.49 for outpatient contact with a nephrology department after AKI. Similar variations were found across municipality categories.

CONCLUSIONS

Within the uniform Danish healthcare system, we found modest regional variation in AKI incidence. The mortality after AKI was similar; however, CKD, biochemical follow-up and nephrology follow-up after AKI varied across regions and municipality categories.

Mendelian Randomization Analysis of Systemic Iron Status and Risk of Different Types of Kidney Disease

With rapid increases in incidence, diverse subtypes, and complicated etiologies, kidney disease remains a global public health problem. Iron, as an essential trace element, has pleiotropic effects on renal function and the progression of kidney diseases. A two-sample Mendelian randomization (MR) analysis was implemented to determine the potential causal effects between systemic iron status on different kidney diseases. Systemic iron status was represented by four iron-related biomarkers: serum iron, ferritin, transferrin saturation (TfSat), and total iron binding capacity (TIBC). For systemic iron status, 163,511, 246,139, 131,471, and 135,430 individuals were included in the genome-wide association study (GWAS) of serum iron, ferritin, TfSat, and TIBC, respectively. For kidney diseases, 653,143 individuals (15,658 cases and 637,485 controls), 657,076 individuals (8160 cases and 648,916 controls), and 659,320 individuals (10,404 cases and 648,916 controls) were included for immunoglobulin A nephropathy (IgAN), acute kidney disease (AKD), and chronic kidney disease (CKD), respectively. Our MR results showed that increased serum iron [odds ratio (OR): 1.10; 95% confidence interval (95% CI): 1.04, 1.16; p < 0.0042], ferritin (OR: 1.30; 95% CI: 1.14, 1.48; p < 0.0042), and TfSat (OR: 1.07; 95% CI: 1.04, 1.11; p < 0.0042)] and decreased TIBC (OR: 0.92; 95% CI: 0.88, 0.97; p < 0.0042) were associated with elevated IgAN risk. However, no significant associations were found between systemic iron status and AKD or CKD. In our MR study, the genetic evidence supports elevated systemic iron status as a causal effect on IgAN, which suggests a potential protective effect of iron chelation on IgAN patients.

Fifteen-year temporal changes in rates of acute kidney injury among children in Denmark

BACKGROUND

We aimed to examine temporal changes in the annual rate of acute kidney injury (AKI) in Danish children and associated changes in patient characteristics including potential underlying risk factors.

METHODS

In this population-based cohort study, we used plasma creatinine measurements from Danish laboratory databases to identify AKI episodes in children aged 0-17 years from 2007 to 2021. For each child, the first AKI episode per calendar year was included. We estimated the annual crude and sex- and age-standardized AKI rate as the number of children with an AKI episode divided by the total number of children as reported by census numbers. Using Danish medical databases, we assessed patient characteristics including potential risk factors for AKI, such as use of nephrotoxic medication, surgery, sepsis, and perinatal factors.

RESULTS

In total, 14,200 children contributed with 16,345 AKI episodes over 15 years. The mean annual AKI rate was 148 (95% CI: 141-155) per 100,000 children. From 2007 to 2021, the annual AKI rate demonstrated minor year-to-year variability without any discernible overall trend. The highest AKI rate was recorded in 2007 at 174 (95% CI: 161-187) per 100,000 children, while the lowest rate occurred in 2012 at 129 (95% CI: 118-140) per 100,000 children. In 2021, the AKI rate was 148 (95% CI: 141-155) per 100,000 children. Characteristics of children with AKI were similar throughout the study period.

CONCLUSION

The rate of AKI among Danish children was stable from 2007 to 2021 with little variation in patient characteristics over time.

Potential therapeutic applications of circular RNA in acute kidney injury

Acute kidney injury (AKI) is a common clinical syndrome characterized by a rapid deterioration in renal function, manifested by a significant increase in creatinine and a sharp decrease in urine output. The incidence of morbidity and mortality associated with AKI is on the rise, with most patients progressing to chronic kidney disease or end-stage renal disease. Treatment options for patients with AKI remain limited. Circular RNA (circRNA) is a wide and diverse class of non-coding RNAs that are present in a variety of organisms and are involved in gene expression regulation. Studies have shown that circRNA acts as a competing RNA, is involved in disease occurrence and development, and has potential as a disease diagnostic and prognostic marker. CircRNA is involved in the regulation of important biological processes, including apoptosis, oxidative stress, and inflammation. This study reviews the current status and progress of circRNA research in the context of AKI.

Recovery of kidney function after acute kidney disease-a multi-cohort analysis

BACKGROUND

There are no consensus definitions for evaluating kidney function recovery after acute kidney injury (AKI) and acute kidney disease (AKD), nor is it clear how recovery varies across populations and clinical subsets. We present a federated analysis of four population-based cohorts from Canada, Denmark and Scotland, 2011-18.

METHODS

We identified incident AKD defined by serum creatinine changes within 48 h, 7 days and 90 days based on KDIGO AKI and AKD criteria. Separately, we applied changes up to 365 days to address widely used e-alert implementations that extend beyond the KDIGO AKI and AKD timeframes. Kidney recovery was based on resolution of AKD and a subsequent creatinine measurement below 1.2× baseline. We evaluated transitions between non-recovery, recovery and death up to 1 year; within age, sex and comorbidity subgroups; between subset AKD definitions; and across cohorts.

RESULTS

There were 464 868 incident cases, median age 67-75 years. At 1 year, results were consistent across cohorts, with pooled mortalities for creatinine changes within 48 h, 7 days, 90 days and 365 days (and 95% confidence interval) of 40% (34%-45%), 40% (34%-46%), 37% (31%-42%) and 22% (16%-29%) respectively, and non-recovery of kidney function of 19% (15%-23%), 30% (24%-35%), 25% (21%-29%) and 37% (30%-43%), respectively. Recovery by 14 and 90 days was frequently not sustained at 1 year. Older males and those with heart failure or cancer were more likely to die than to experience sustained non-recovery, whereas the converse was true for younger females and those with diabetes.

CONCLUSION

Consistently across multiple cohorts, based on 1-year mortality and non-recovery, KDIGO AKD (up to 90 days) is at least prognostically similar to KDIGO AKI (7 days), and covers more people. Outcomes associated with AKD vary by age, sex and comorbidities such that older males are more likely to die, and younger females are less likely to recover.

Lanthanum Hydroxide and Chronic Kidney Disease Mineral and Bone Disorder: A Rat Model

OBJECTIVE

To investigate the pharmacological effects and molecular mechanisms of lanthanum hydroxide(LH) on ectopic mineralization of soft tissue and abnormal bone in rats with acute kidney injury(AKI).

METHODS

Wistar rats were modeled by 5/6 nephrectomy. After the operation, the rats were divided into different groups, the biochemical indexes of serum collected at different times. LH was administered by intragastric tube at doses of 0.4, 0.2, and 0.1g/kg, respectively. Rats were sacrificed in the 16th week after LH treatment. Observation of pathological changes in tissues were made by specific staining. Western Blot, Real-Time Quantitative PCR, and immunohistochemistry techniques were used to detect the impact on pathway-related proteins.

RESULTS

Compared with the control group (no LH administered), the serum phosphate level of the LH group was significantly reduced (p<0.01), calcification of the thoracic aorta was reduced (p<0.05, p<0.01) (Serum biochemical tests before dosing and during drug treatment cycles), renal fibrosis was improved (p<0.01), nuclear entry of nuclear factor kappa-B (NF-κB) was reduced (p<0.01), and the expression of the smooth muscle protein 22α (SM22α) was significantly increased (p<0.01). The expression of osteogenic marker genes was decreased. In addition, compared with the controls, the receptor activator for nuclear factor-κB ligand/osteoprotegerin (RANKL/OPG) ratio of the femur in the model group was increased (p<0.05).

CONCLUSION

LH can inhibit the occurrence and development of vascular calcification and bone abnormalities in AKI rats by inhibiting the NF-κB and RANKL/OPG signaling pathways.

Amlodipine alleviates renal ischemia/reperfusion injury in rats through Nrf2/Sestrin2/PGC-1α/TFAM Pathway

BACKGROUND

Previously, observational studies showed that amlodipine can mitigate calcineurin inhibitor- and contrast-induced acute kidney injury (AKI). Herein, we aimed to measure the effect of amlodipine on renal ischemia/reperfusion (I/R) injury and find the underlying mechanisms.

MATERIALS AND METHODS

Bilateral renal I/R was induced by clamping the hilum of both kidneys for 30 min. The first dose of amlodipine 10 mg/kg was gavaged before anesthesia. The second dose of amlodipine was administered 24 h after the first dose. Forty-eight hours after I/R, rats were anesthetized, and their blood and tissue specimens were collected.

RESULTS

Amlodipine significantly decreased the elevated serum levels of creatinine and blood urea nitrogen (BUN) and mitigated tissue damage in hematoxylin & eosin (H&E) staining. Amlodipine strongly reduced the tissue levels of malondialdehyde (MDA), interleukin 1β (IL1β), and tumor necrosis factor α (TNF-α). Amlodipine enhanced antioxidant defense by upregulating nuclear factor erythroid 2-related factor 2 (Nrf2) and Sestrin2. Furthermore, amlodipine significantly improved mitochondrial biogenesis by promoting Sestrin2/peroxisome proliferator-activated receptor-gamma coactivator (PGC-1α)/mitochondrial transcription factor A (TFAM) pathway. It also enhanced autophagy and attenuated apoptosis, evidenced by increased LC3-II/LC3-I and bcl2/bax ratios after renal I/R.

CONCLUSION

These findings suggest that amlodipine protects against renal I/R through Nrf2/Sestrin2/PGC-1α/TFAM Pathway.

Lasmiditan restores mitochondrial quality control mechanisms and accelerates renal recovery after ischemia-reperfusion injury

BACKGROUND

Mitochondrial dysfunction is a well-established result of acute kidney injury (AKI). Previously, we identified that 5-hydroxytryptamine 1F (5-HT1F) receptor agonism with lasmiditan induces mitochondrial biogenesis (MB) and improves renal vasculature and function in an AKI mouse model. We hypothesize that lasmiditan also modulates mitochondrial dynamics and mitophagy in a mouse model of AKI.

METHODS

Male mice were subjected to renal ischemia/reperfusion (I/R) and treated daily with lasmiditan (0.3 mg/kg) or vehicle beginning 24 h after injury for 3 or 6d. Serum creatinine was measured to estimate glomerular filtration. Electron microscopy was used to assess mitochondrial morphology and mitophagy. Mitochondrial-related protein were confirmed with immunoblotting. Mitochondrial function was assessed with ATP measurements.

RESULTS

Lasmiditan treatment improved mitochondrial and kidney recovery as early as 3d post-AKI, as evidenced by increased ATP, and decreased serum creatinine, respectively. Electron micrographs of renal cortices revealed that lasmiditan also decreased mitochondrial damage and increased mitochondrial area and size by 6d after I/R injury. Additionally, lasmiditan treatment increased mitolysosomes by 3d, indicating induction of mitophagy. Phosphorylation of mitophagy-related proteins were also increased in the renal cortices of lasmiditan-treated AKI mice 3d after I/R injury, whereas fusion-related proteins were increased at 6d after I/R injury.

CONCLUSION

These data reveal that lasmiditan accelerates renal recovery, restores normal mitochondrial membrane and cristae morphology, decreases excessive mitochondrial fission, and accelerates mitophagy post-AKI in a time-dependent manner, establishing mitochondrial function and recovery from AKI.

Acute kidney injury associated with nephrotoxic drugs in critically ill patients: a multicenter cohort study using electronic health record data

Background

Nephrotoxic drugs frequently cause acute kidney injury (AKI) in adult intensive care unit (ICU) patients. However, there is a lack of large pharmaco-epidemiological studies investigating the associations between drugs and AKI. Importantly, AKI risk factors may also be indications or contraindications for drugs and thereby confound the associations. Here, we aimed to estimate the associations between commonly administered (potentially) nephrotoxic drug groups and AKI in adult ICU patients whilst adjusting for confounding.

Methods

In this multicenter retrospective observational study, we included adult ICU admissions to 13 Dutch ICUs. We measured exposure to 44 predefined (potentially) nephrotoxic drug groups. The outcome was AKI during ICU admission. The association between each drug group and AKI was estimated using etiological cause-specific Cox proportional hazard models and adjusted for confounding. To facilitate an (independent) informed assessment of residual confounding, we manually identified drug group-specific confounders using a large drug knowledge database and existing literature.

Results

We included 92 616 ICU admissions, of which 13 492 developed AKI (15%). We found 14 drug groups to be associated with a higher hazard of AKI after adjustment for confounding. These groups included established (e.g. aminoglycosides), less well established (e.g. opioids) and controversial (e.g. sympathomimetics with α- and β-effect) drugs.

Conclusions

The results confirm existing insights and provide new ones regarding drug associated AKI in adult ICU patients. These insights warrant caution and extra monitoring when prescribing nephrotoxic drugs in the ICU and indicate which drug groups require further investigation.

Utilising routine clinical laboratory data to support quality improvement in health care: Application of a national acute kidney injury alert system as a proof of concept

BACKGROUND

Acute kidney injury (AKI) is a global health issue known to cause avoidable harm and death. Improvement in its prevention and management is therefore considered an important goal for the health-care sector. The work here aimed to develop a tool which could be used to robustly and reliably measure, monitor, and compare the effectiveness of health-care interventions related to AKI across the Welsh NHS, a mechanism which did not exist previously.

METHODS

Using serum creatinine (SCr) as a biomarker for AKI and a validated national data-set collected from the all Wales Laboratory Information Management System, work involved applying Donabedian's framework to develop indicators with which to measure outcomes related to AKI, and exploring the potential of statistical process control (SPC) techniques for analysing data on these indicators.

RESULTS

Rate of AKI incidence and 30-day AKI-associated mortality are proposed as valid, feasible indicators with which to measure the effectiveness of health-care interventions related to AKI. The control chart, funnel plot, and Pareto chart are proposed as appropriate, robust SPC techniques to analyse and visualise variation in AKI-related outcomes.

CONCLUSIONS

This work demonstrates that routinely collected large SCr data offer a significant opportunity to monitor and therefore inform improvement in patient outcomes related to AKI. Moreover, while this work concerns utilisation of SCr data for improvement in AKI strategies, it is a proof of concept which could be replicated for other routinely collected clinical laboratory data, to improve the prevention and/or management of the conditions to which they relate.

Electronic Acute Kidney Injury Alert at the Brandenburg Medical School: Implementation and Follow-Up

INTRODUCTION

Acute kidney injury (AKI) substantially worsens the prognosis of hospitalized patients worldwide. In order to optimize early AKI recognition and therapeutic intervention, AKI alert systems have been implemented and evaluated in the past. Herein, we aimed to analyze outcome variables of AKI patients under the conditions of a de novo-established AKI alert system at the Brandenburg Hospital of the Brandenburg Medical School.

METHODS

Automated e-mail messages were generated and sent to the nephrologist with responsibility based on an electronic algorithm. The message was exclusively generated if one of the two first KDIGO criteria was fulfilled. During period 1, all alerts were ignored. During the second period, every alert was followed up, coupled with therapeutic management of respective individuals according to an AKI care bundle. Endpoints were in-hospital death, need for dialysis, and renal recovery.

RESULTS

In periods 1 and 2, 200 and 112 patients were included. In period 1, 150 out of 200 AKI alerts were identified as correct (75%); in the second period, 93 out of 112 AKI alerts were accepted as correct (83%) (p = 0.16). Kidney replacement therapy was initiated in 21 (14%) of all period 1 patients and in 32 (34.4%) of the period 2 patients (p = 0.017). In-hospital mortality of affected patients was 24 (16%) in period 1 and 21 (22.5%) in period 2 (p = 0.4). Restoration of kidney function was 69 (46%) in period 1 and 45 (48.3%) in period 2 (p = 0.71).

CONCLUSIONS

We finally conclude that an AKI alert system, as implemented and followed-up in our study, did not significantly improve clinically relevant endpoints in AKI patients. Potential weaknesses were the lack of documentation of the time between receiving the alert and patient contact, and physicians in responsibility were not particularly informed about the alert system.

Clinical courses of acute kidney injury in hospitalized patients: a multistate analysis

Persistence of acute kidney injury (AKI) or insufficient recovery of renal function was associated with reduced long-term survival and life quality. We quantified AKI trajectories and describe transitions through progression and recovery among hospitalized patients. 245,663 encounters from 128,271 patients admitted to UF Health between 2012 and 2019 were retrospectively categorized according to the worst AKI stage experienced within 24-h periods. Multistate models were fit for describing characteristics influencing transitions towards progressed or regressed AKI, discharge, and death. Effects of age, sex, race, admission comorbidities, and prolonged intensive care unit stay (ICU) on transition rates were examined via Cox proportional hazards models. About 20% of encounters had AKI; where 66% of those with AKI had Stage 1 as their worst AKI severity during hospitalization, 18% had Stage 2, and 16% had Stage 3 AKI (12% with kidney replacement therapy (KRT) and 4% without KRT). At 3 days following Stage 1 AKI, 71.1% (70.5-71.6%) were either resolved to No AKI or discharged, while recovery proportion was 38% (37.4-38.6%) and discharge proportion was 7.1% (6.9-7.3%) following AKI Stage 2. At 14 days following Stage 1 AKI, patients with additional frail conditions stay had lower transition proportion towards No AKI or discharge states. Multistate modeling framework is a facilitating mechanism for understanding AKI clinical course and examining characteristics influencing disease process and transition rates.

The role of N6-methyladenosine (m6A) in kidney diseases

Chemical modifications are a specific and efficient way to regulate the function of biological macromolecules. Among them, RNA molecules exhibit a variety of modifications that play important regulatory roles in various biological processes. More than 170 modifications have been identified in RNA molecules, among which the most common internal modifications include N6-methyladenine (m6A), n1-methyladenosine (m1A), 5-methylcytosine (m5C), and 7-methylguanine nucleotide (m7G). The most widely affected RNA modification is m6A, whose writers, readers, and erasers all have regulatory effects on RNA localization, splicing, translation, and degradation. These functions, in turn, affect RNA functionality and disease development. RNA modifications, especially m6A, play a unique role in renal cell carcinoma disease. In this manuscript, we will focus on the biological roles of m6A in renal diseases such as acute kidney injury, chronic kidney disease, lupus nephritis, diabetic kidney disease, and renal cancer.

Community-acquired versus hospital-acquired acute kidney injury at a large Australian metropolitan quaternary referral centre: incidence, associations and outcomes

BACKGROUND

There is increasing global incidence of acute kidney injury (AKI) and significant short- and long-term impacts on patients.

AIMS

To determine incidence and outcomes of community-acquired AKI (CA-AKI) and hospital-acquired AKI (HA-AKI) among inpatients in the Australian healthcare setting using modern health information systems.

METHODS

A retrospective cohort study of adult patients admitted to a quaternary hospital in Melbourne, Australia, between 1 January 2018 and 31 December 2019 utilising an electronic data warehouse. Participants included adult patients admitted for >24 h who had more than one serum creatinine level recorded during admission. Kidney transplant and maintenance dialysis patients were excluded. Main outcomes measured included AKI, as classified by the Kidney Disease Improving Global Outcomes (KDIGO) criteria, hospital length of stay and 30-day mortality.

RESULTS

A total of 6477 AKI episodes was identified across 43 791 admissions. Of all AKI episodes, 77% (n = 5011), 15% (n = 947) and 8% (n = 519) were KDIGO stage 1, 2 and 3 respectively. HA-AKI accounted for 55.9% episodes. Patients required intensive care unit admission in 22.7% (n = 1100) of CA-AKI and 19.3% (n = 935) of HA-AKI, compared with 7.5% (n = 2815) of patients with no AKI (P = 0.001). Patients with AKI were older with more co-morbidities, particularly chronic kidney disease (CKD). Length of stay was longer in CA-AKI (8.8 days) and HA-AKI (11.8 days) compared with admissions without AKI (4.9 days; P < 0.001). Thirty-day mortality was increased with CA-AKI (10.2%) and HA-AKI (12.8%) compared with no AKI (3.7%; P < 0.001).

CONCLUSION

The incidence of AKI detected by the electronic data warehouse was higher than previously reported. Patients who experienced AKI had greater morbidity and mortality. CKD was an important risk factor for AKI in hospitalised patients.

Assessment of severity scoring systems for predicting mortality in critically ill patients receiving continuous renal replacement therapy

The incidence of acute kidney injury (AKI) is increasing every year and many patients with AKI admitted to the intensive care unit (ICU) require continuous renal replacement therapy (CRRT). This study compared and analyzed severity scoring systems to assess their suitability in predicting mortality in critically ill patients receiving CRRT. Data from 612 patients receiving CRRT in four ICUs of the Korea University Medical Center between January 2016 and November 2018 were retrospectively collected. The mean age of all patients was 67.6 ± 14.8 years, and the proportion of males was 59.6%. The endpoints were in-hospital mortality and 7-day mortality from the day of CRRT initiation to the date of death. The Program to Improve Care in Acute Renal Disease (PICARD), Demirjian's, Acute Physiology and Chronic Health Evaluation (APACHE) II, Simplified Acute Physiology Score (SAPS) 3, Sequential Organ Failure Assessment (SOFA), Multiple Organ Dysfunction Score (MODS), and Liano's scores were used to predict mortality. The in-hospital and 7-day mortality rates in the study population were 72.7% and 45.1%, respectively. The area under the receiver operator characteristic curve (AUROC) revealed the highest discrimination ability for Demirjian's score (0.770), followed by Liano's score (0.728) and APACHE II (0.710). The AUROC curves for the SAPS 3, MODS, and PICARD were 0.671, 0.665, and 0.658, respectively. The AUROC of Demirjian's score was significantly higher than that of the other scores, except for Liano's score. The Hosmer-Lemeshow test on Demirjian's score showed a poor fit in our analysis; however, it was more acceptable than general severity scores. Kidney-specific severity scoring systems showed better performance in predicting mortality in critically ill patients receiving CRRT than general severity scoring systems.

Nephroprotective mechanisms of Rhizoma Chuanxiong and Radix et Rhizoma Rhei against acute renal injury and renal fibrosis based on network pharmacology and experimental validation

The molecular mechanisms of Rhizoma Chuanxiong (Chuanxiong, CX) and Rhei Radix et Rhizoma (Dahuang, DH) in treating acute kidney injury (AKI) and subsequent renal fibrosis (RF) were investigated in this study by applying network pharmacology and experimental validation. The results showed that aloe-emodin, (-)-catechin, beta-sitosterol, and folic acid were the core active ingredients, and TP53, AKT1, CSF1R, and TGFBR1 were the core target genes. Enrichment analyses showed that the key signaling pathways were the MAPK and IL-17 signaling pathways. In vivo experiments confirmed that Chuanxiong and Dahuang pretreatments significantly inhibited the levels of SCr, BUN, UNAG, and UGGT in contrast media-induced acute kidney injury (CIAKI) rats (p < 0.001). The results of Western blotting showed that compared with the control group, the protein levels of p-p38/p38 MAPK, p53, and Bax in the contrast media-induced acute kidney injury group were significantly increased, and the levels of Bcl-2 were significantly reduced (p < 0.001). Chuanxiong and Dahuang interventions significantly reversed the expression levels of these proteins (p < 0.01). The localization and quantification of p-p53 expression in immunohistochemistry technology also support the aforementioned results. In conclusion, our data also suggest that Chuanxiong and Dahuang may inhibit tubular epithelial cell apoptosis and improve acute kidney injury and renal fibrosis by inhibiting p38 MAPK/p53 signaling.

Learning Curve for Temporary Hemodialysis Catheter Placement

BACKGROUND

Training is essential for the safe and uncomplicated placement of hemodialysis catheters. This study explores the learning curve of this procedure.

METHODS

In this prospective study, 60 patients who needed emergency hemodialysis without vascular access were included. All catheters were placed under ultrasound guidance. One nephrologist was included in each two groups, one to be consisted of a junior, and one to be consisted of a senior. Learning curves were created using the cumulative total methodology and receiver operating characteristic curve analyses.

RESULTS

The patients' mean age was 67.92 ± 14.23 years. The mean catheter insertion time of the senior nephrologist was significantly shorter than that of the junior. According to cumulative total analysis, the junior group's maximum learning point overlaps with patient 22. When the confidence intervals of the study durations of both groups were examined, they overlapped in the 95% confidence interval starting from the 19th patient. When the mean catheter insertion time of the senior and the mean of the last 12 patients of the junior were compared, there was no significant difference between them (F = 15.827, P = .092). The receiver operating characteristic curve analysis showed a cutoff value of 320 seconds for the junior group compared with the senior group, indicating an overlap in case 22 for the junior nephrologist.

CONCLUSION

This study suggests that 22 catheter insertions under the supervision of a senior nephrologist are needed to complete the learning curve for a junior nephrologist. If the number of nephrologists at the center is limited, safe catheter insertion may be allowed after 19 insertions.

Air Pollution and Acute Kidney Injury in the U.S. Medicare Population: A Longitudinal Cohort Study

BACKGROUND

Recent studies have reported the association between air pollution exposure and reduced kidney function. However, it is unclear whether air pollution is associated with an increased risk of acute kidney injury (AKI).

OBJECTIVES

To address this gap in knowledge, we investigated the effect estimates of long-term exposures to fine particulate matter [PM ≤ 2.5 μ m in aerodynamic diameter (PM 2.5 )], nitrogen dioxide (NO 2 ), and ozone (O 3 ) on the risk of first hospital admission for AKI using nationwide Medicare data.

METHODS

This nationwide population-based longitudinal cohort study included 61,300,754 beneficiaries enrolled in Medicare Part A fee-for-service (FFS) who were ≥ 65 years of age and resided in the continental United States from the years 2000 through 2016. We applied Cox-equivalent Poisson models to estimate the association between air pollution and first hospital admission for AKI.

RESULTS

Exposure to PM 2.5 , NO 2 , and O 3 was associated with increased risk for first hospital admission for AKI, with hazard ratios (HRs) of 1.17 (95% CI: 1.16, 1.19) for a 5 - μ g / m 3 increase in PM 2.5 , 1.12 (95% CI: 1.11, 1.13) for a 10 -ppb increase in NO 2 , and 1.03 (95% CI: 1.02, 1.04) for a 10 -ppb increase in summer-period O 3 (June to September). The associations persisted at annual exposures lower than the current National Ambient Air Quality Standard.

DISCUSSION

This study found an association between exposures to air pollution and the risk of the first hospital admission with AKI, and this association persisted even at low concentrations of air pollution. Our findings provide beneficial implications for public health policies and air pollution guidelines to alleviate health care expenditures and the disease burden attributable to AKI. https://doi.org/10.1289/EHP10729.

Role of increased neutrophil extracellular trap formation on acute kidney injury in COVID-19 patients

Background

A strong association between elevated neutrophil extracellular trap (NET) levels and poor clinical outcomes in patients with coronavirus infection 2019 (COVID-19) has been reported. However, while acute kidney injury (AKI) is a common complication of COVID-19, the role of NETs in COVID-19-associated AKI is unclear. We investigated the association between elevated NETs and AKI and the prognostic role of NETs in COVID-19 patients.

Methods

Two representative markers of NETs, circulating nucleosomes and myeloperoxidase-DNA, were measured in 115 hospitalized patients. Serum levels of interleukin [IL]-6, monocyte chemotactic protein-1 [MCP-1], plasma von Willebrand factor (vWF) and urinary biomarkers of renal tubular damage (β2-microglobulin [β2M] and kidney injury molecule 1 [KIM-1]) were measured.

Results

AKI was found in 43 patients (37.4%), and pre-existing chronic kidney disease (CKD) was a strong risk factor for AKI. Higher circulating NET levels were a significant predictor of increased risk of initial ICU admission, in-hospital mortality (adjusted HR 3.21, 95% CI 1.08–9.19) and AKI (OR 3.67, 95% CI 1.30-10.41), independent of age, diabetes, pre-existing CKD and IL-6 levels. There were strong correlations between circulating nucleosome levels and urinary KIM-1/creatinine (r=0.368, p=0.001) and β2M (r=0.218, p=0.049) levels. NETs were also strongly closely associated with serum vWF (r = 0.356, p&lt;0.001), but not with IL-6 or MCP-1 levels.

Conclusions

Elevated NETs were closely associated with AKI, which was a strong predictor of mortality. The close association between NETs and vWF may suggest a role for NETs in COVID-19-associated vasculopathy leading to AKI.

Drug-related causes attributed to acute kidney injury and their documentation in intensive care patients

PURPOSE

To investigate drug-related causes attributed to acute kidney injury (DAKI) and their documentation in patients admitted to the Intensive Care Unit (ICU).

METHODS

This study was conducted in an academic hospital in the Netherlands by reusing electronic health record (EHR) data of adult ICU admissions between November 2015 to January 2020. First, ICU admissions with acute kidney injury (AKI) stage 2 or 3 were identified. Subsequently, three modes of DAKI documentation in EHR were examined: diagnosis codes (structured data), allergy module (semi-structured data), and clinical notes (unstructured data).

RESULTS

n total 8124 ICU admissions were included, with 542 (6.7%) ICU admissions experiencing AKI stage 2 or 3. The ICU physicians deemed 102 of these AKI cases (18.8%) to be drug-related. These DAKI cases were all documented in the clinical notes (100%), one in allergy module (1%) and none via diagnosis codes. The clinical notes required the highest time investment to analyze.

CONCLUSIONS

Drug-related causes comprise a substantial part of AKI in the ICU patients. However, current unstructured DAKI documentation practice via clinical notes hampers our ability to gain better insights about DAKI occurrence. Therefore, both automating DAKI identification from the clinical notes and increasing structured DAKI documentation should be encouraged.

The Tryptophan and Kynurenine Pathway Involved in the Development of Immune-Related Diseases

The tryptophan and kynurenine pathway is well-known to play an important role in nervous, endocrine, and immune systems, as well as in the development of inflammatory diseases. It has been documented that some kynurenine metabolites are considered to have anti-oxidative, anti-inflammatory, and/or neuroprotective properties. Importantly, many of these kynurenine metabolites may possess immune-regulatory properties that could alleviate the inflammation response. The abnormal activation of the tryptophan and kynurenine pathway might be involved in the pathophysiological process of various immune-related diseases, such as inflammatory bowel disease, cardiovascular disease, osteoporosis, and/or polycystic ovary syndrome. Interestingly, kynurenine metabolites may be involved in the brain memory system and/or intricate immunity via the modulation of glial function. In the further deliberation of this concept with engram, the roles of gut microbiota could lead to the development of remarkable treatments for the prevention of and/or the therapeutics for various intractable immune-related diseases.

Twenty-Three-Year Trends in the Use of Potentially Nephrotoxic Drugs in Denmark

Background

The occurrence of acute and chronic kidney diseases has been rising in the last decades. Although drug use is a common risk factor for impaired kidney function, changes in utilization of potential nephrotoxic drugs have received little attention.

Purpose

To describe temporal trends in the utilization of potentially nephrotoxic drugs in Denmark between 1999 and 2021.

Methods

Specific drugs known or suspected to be nephrotoxic were identified in the literature. Data on the sold defined daily doses (DDDs) of potentially nephrotoxic drugs between 1999 and 2021 were retrieved using the Danish Register of Medical Product Statistics. Trends in sales of DDDs per 1000 inhabitants per day were tabulated and illustrated graphically.

Results

From 1999 to 2021, the total sale of all selected drugs increased from 286 to 457 DDDs per 1000 inhabitants per day. The overall sale reached a preliminary peak in 2012 with 449 DDDs per 1000 inhabitants per day and remained relatively stable thereafter until reaching an all-time high in 2021 with 457 DDDs per 1000 inhabitants per day. Contributing with the majority in volume, sales of drugs inhibiting the renin-angiotensin-aldosterone system (RAAS) increased dramatically throughout the period. The same was observed for acetaminophen, methotrexate, tacrolimus, and iodinated contrast dye. In contrast, the sales of diuretics, acetylsalicylic acid, and ciclosporin decreased during the last decade of the study period.

Conclusion

From 1999-2021 considerable changes in sales of potentially nephrotoxic drugs were observed. In general, the sales increased, in volume predominated by RAAS inhibiting drugs. This increase in sales of potential nephrotoxins could contribute to an increasing occurrence of kidney diseases.

Quality of care in patients undergoing coronary angiography with a known risk of contrast-associated acute kidney injury: a retrospective observational study

OBJECTIVE

Iodinated contrast medium is potentially nephrotoxic in susceptible individuals. The aim of this retrospective observational study was to determine the impact of hospital-wide implementation of a guideline to prevent contrast-associated acute kidney injury (CA-AKI) on quality of care and outcomes.

METHODS

A hospital-wide guideline for management of patients known to be at risk of CA-AKI was implemented in April 2019. All patients who underwent coronary angiography at our institution between November 2018 and March 2019 (period 1, before introduction of the guideline) and between August and December 2019 (period 2, after introduction of the guideline) were enrolled.

RESULTS

In total, 561 patients were enrolled for period 1 and 578 for period 2. CA-AKI was impossible to diagnose in many patients because of missing post-procedure creatinine control data. Preventive measures were initiated more often in period 2 than in period 1 and in older patients than in younger patients. Preventive measures were not initiated in at least 50% of patients at risk of CA-AKI despite implementation of the guideline.

CONCLUSIONS

Management of patients at known risk of CA-AKI remains inadequate at our institution even after introduction of a guideline. Physicians should receive organized training in acute kidney injury.

Incidence and Recovery of Acute Kidney Injury in Diabetic and Nondiabetic Patients with Foot Infections

BACKGROUND

The aim of this study was to evaluate the incidence and recovery of acute kidney injury (AKI) in patients admitted to the hospital with and without diabetes mellitus (DM) with foot infections.

METHODS

We retrospectively reviewed 294 patients with DM and 88 without DM admitted to the hospital with foot infections. The Kidney Disease: Improving Global Outcomes guidelines were used to define AKI. Recovery was divided into three categories: full, partial, and no recovery within 90 days of the index AKI.

RESULTS

The AKI incidence was 3.0 times higher in patients with DM (DM 48.5% versus no DM 23.9%; 95% confidence interval [CI], 1.74-5.19; P < .01). Acute kidney injury incidence was similar at each stage in people with and without DM (stage 1, DM 58.1% versus no DM 47.6%; stage 2, DM 23.3% versus no DM 33.3%, and stage 3, DM 18.6% versus no DM 19.1%). Twenty-nine patients with diabetes had a second AKI event and four had a third event. In patients without DM, one patient had a second AKI. Cumulative AKI incidence was 4.7 times higher in people with DM (DM 60.9% versus no DM 25.0%; 95% CI, 2.72-8.03; P < .01). Patients with diabetes progressed to chronic kidney disease or in chronic kidney disease stage 39.4% of the time. Patients without diabetes progressed 16.7% of the time, but this trend was not significant (P = .07). Complete recovery was 3.8 times more likely in patients without diabetes (95% CI, 1.26-11.16; P = .02).

CONCLUSIONS

Acute kidney injury incidence is higher in patients with diabetes, and complete recovery after an AKI is less likely compared to patients without diabetes.

Cisplatin and AKI: an ongoing battle with new perspectives—a narrative review

Acute kidney injury (AKI) is a growing global health problem with increased mortality and morbidity. Cisplatin is achemotherapy drug first introduced in 1978, and since then, it became one of the most widely used and successful anti-cancer medication. However, there are risks associated with cisplatin administration, such as nephrotoxicity. Mechanisms of nephrotoxicity include proximal tubular injury, DNA damage, apoptosis, inflammation, oxidative stress, and vascular injury. Although various protocols are being used in clinical practice in nephrotoxicity prevention due to cisplatin, there are no clear guidelines regarding this approach. Most recommendations include hydration and avoiding additional nephrotoxic drugs. To prevent nephrotoxicity, future perspectives could rely on natural products, such as flavonoids or saponins or pharmacological products, such as aprepitant, but data are scarce in this direction. Repetitive administration of cisplatin could cause subclinical kidney injury, which over time, leads to chronic kidney disease (CKD). Therefore, more studies are needed to determine possible ways to prevent nephrotoxicity and avoid the burden of CKD worldwide.

The Impact of a Mediterranean-like Diet with Controlled Protein Intake on the Onco-Nephrological Scenario: Time for a New Perspective

Chronic kidney disease (CKD) represents a frequent comorbidity in cancer patients, especially for patients affected by urological cancers. Unfortunately, impaired kidney function may limit the choice of adequate oncological treatments for their potential nephrotoxicity or due to contraindications in case of a low glomerular filtration rate. For these patients, tailored nephrological and nutritional management is mandatory. The K-DIGO guidelines do not define whether the nutritional management of CKD could be useful also in CKD patients affected by urological cancer. In fact, in clinical practice, oncological patients often receive high-protein diets to avoid malnutrition. In our study, we investigated the nutritional and nephrological impact of a Mediterranean-like diet with a controlled protein intake (MCPD) on a cohort of 82 stage III-IV CKD patients. We compared two cohorts: one of 31 non-oncological CKD patients and the other of 51 oncological patients with CKD. The use of an MCPD had a favorable impact on both the oncological and non-oncological CKD patients with an amelioration in all the investigated parameters and with a better quality of life, with no cases of malnutrition or AKI.

Routine Clinical Care Creatinine Data in Denmark - An Epidemiological Resource for Nationwide Population-Based Studies of Kidney Disease

PURPOSE

Creatinine data are key in identifying acute and chronic kidney disease. In Denmark, routine clinical care creatinine data have been collected regionally in the Clinical Laboratory Information System Research Database (LABKA) since the 1990s and nationwide in the Register of Laboratory Results for Research (RLRR) since 2013. Here we describe the geographical coverage of the databases and characteristics of Danish individuals with creatinine tests. This information is pivotal for the design and interpretation of studies using these data to examine kidney disease epidemiology.

PATIENTS AND METHODS

We included all creatinine tests in LABKA and RLRR from 1990 through 2018. The daily number of creatinine tests by municipality and region of residence were plotted and geographical coverage was ascertained. In addition, we characterized a contemporary cohort of creatinine-tested individuals in 2016-2018.

RESULTS

During 1990-2018, 61,011,941 creatinine tests were available for 4,647,966 unique Danish residents. The North Denmark Region was the first region to achieve complete reporting in November 2004, and nationwide reporting was complete starting in October 2015. In each year from 2016 to 2018, more than a third of Danish residents had a recorded creatinine measurement, with the highest proportion of tested individuals aged 77-87 years and the lowest proportion aged 3-5 years. During 2016-2018, the creatinine-tested cohort had a median age of 53 years (IQR, 35-67 years) and included 54.3% women. The most common comorbidity was a hospital-based diagnosis of hypertension (12.0%), and the most common prescription drug was angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers (15.8%).

CONCLUSION

In combination, the population-based LABKA and RLRR databases provide regional creatinine data with long follow-up and nationwide data for the Danish population. There was considerable variation in the time of complete geographical coverage by region, which needs to be considered when using these data for studies on kidney disease epidemiology.

Single-cell analysis of senescent epithelia reveals targetable mechanisms promoting fibrosis

Progressive fibrosis and maladaptive organ repair result in significant morbidity and millions of premature deaths annually. Senescent cells accumulate with aging and after injury and are implicated in organ fibrosis, but the mechanisms by which senescence influences repair are poorly understood. Using 2 murine models of injury and repair, we show that obstructive injury generated senescent epithelia, which persisted after resolution of the original injury, promoted ongoing fibrosis, and impeded adaptive repair. Depletion of senescent cells with ABT-263 reduced fibrosis in reversed ureteric obstruction and after renal ischemia/reperfusion injury. We validated these findings in humans, showing that senescence and fibrosis persisted after relieved renal obstruction. We next characterized senescent epithelia in murine renal injury using single-cell RNA-Seq. We extended our classification to human kidney and liver disease and identified conserved profibrotic proteins, which we validated in vitro and in human disease. We demonstrated that increased levels of protein disulfide isomerase family A member 3 (PDIA3) augmented TGF-β-mediated fibroblast activation. Inhibition of PDIA3 in vivo significantly reduced kidney fibrosis during ongoing renal injury and as such represented a new potential therapeutic pathway. Analysis of the signaling pathways of senescent epithelia connected senescence to organ fibrosis, permitting rational design of antifibrotic therapies.

Kidney nonprocurement in deceased donors with acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is common in deceased organ donors and is associated with high rates of kidney discard by transplant centers. High discard rates may consequently drive nonprocurement of these kidneys by organ procurement organizations. We aimed to study the relationship between donor AKI and kidney nonprocurement.

METHODS

Using U.S. registry data, we identified donors with at least one organ recovered from 2008 to 2018. We compared characteristics of donors with no kidneys procured across AKI stages, and used multivariable logistic regression to evaluate the relationship between AKI severity and kidney nonprocurement.

RESULTS

Overall 14 543 kidneys from 7620 donors were not procured, among which 93% were from donors with AKI. For 6945 donors with no kidneys procured but an extrarenal organ recovered, most had stage 3 (51%), followed by stage 1 (27%) and stage 2 AKI (15%). Nonprocured stage 3 donors were the youngest and had the lowest Kidney Donor Risk Index of all nonprocured donors. Adjusted odds of kidney nonprocurement were 1.14 (95%CI 1.02-1.27) for stage 1, 1.25 (95%CI 1.12-1.41) for stage 2, and 10.37 (95%CI 9.30-11.56) for stage 3 donors, compared to non-AKI donors. Among donors with minimum creatinine <1.5 mg/dl, stage 2 and 3 AKI were still associated with significantly higher odds of nonprocurement.

CONCLUSIONS

AKI severity is a strong risk factor for kidney nonprocurement. Efforts to address the organ shortage should focus on encouraging procurement and utilization of kidneys from deceased donors with severe AKI, given the large and rising prevalence of donor AKI and excellent transplant outcomes with these kidneys.

Chuan Huang Fang combining reduced glutathione in treating acute kidney injury (grades 1–2) on chronic kidney disease (stages 2–4): A multicenter randomized controlled clinical trial

Lack of effective drugs for acute kidney injury (AKI) grades 1–2 is a crucial challenge in clinic. Our previously single-center clinical studies indicated Chuan Huang Fang (CHF) might have nephroprotection in AKI on chronic kidney disease (CKD) (A on C) patients by preventing oxidant damage and inhibiting inflammation. Reduced glutathione (RG) has recently been shown to increase the clinical effectiveness of high-flux hemodialysis among patients with severe AKI. In this multicenter randomized controlled clinical study, we designed a new protocol to assess the efficacy and safety of CHF combining RG in patients with A on C. We also explored therapeutic mechanisms from renal fibrosis biomarkers. 98 participants were randomly and equally divided into the RG and RG + CHF subgroups. The RG and RG + CHF groups received general treatments with RG and a combination of RG and CHF, respectively. The therapy lasted for 2 weeks. In this study, the primary assessment result was a difference in the slope of serum creatinine (Scr) over the course of 2 weeks. The secondary evaluation outcomes were alterations in blood urea nitrogen (BUN), uric acid (UA), estimated glomerular filtration rate (eGFR), urinary AKI biomarkers, renal fibrosis biomarkers (transforming growth factor-β₁ (TGF-β₁), connective tissue growth factor (CTGF)), and traditional Chinese medicine (TCM) symptoms. Furthermore, vital signs and adverse events (AEs) were observed. Both groups had a slower renal function decline after treatment than before treatment. Compared with RG group, more reductions of Scr, BUN, UA, and better improvement of eGFR were observed in RG + CHF group (p < 0.05). Additionally, the levels of urinary AKI biomarkers, renal fibrosis biomarkers, and TCM syndromes were decreased in RG + CHF group versus RG group (p < 0.05). No significant between-group differences were observed of AEs. We thus concluded this novel therapy of CHF combining RG might be a useful method for treating A on C patients.

Long-Term Outcomes of Perioperative Versus Nonoperative Myocardial Infarction: A Danish Population-Based Cohort Study (2000–2016)

Background:

Perioperative myocardial infarction is a serious cardiovascular complication of noncardiac surgery. The clinical course of perioperative myocardial infarction, other than all-cause mortality, is largely unknown. We examined long-term fatal and nonfatal outcomes of perioperative myocardial infarction compared with nonoperative myocardial infarction.

Methods:

We conducted a population-based cohort study of first-time myocardial infarction in Denmark from 2000 to 2016. We calculated cumulative incidence of all-cause mortality, cardiac mortality, recurrent myocardial infarction, heart failure, stroke, venous thromboembolism, acute kidney injury, and kidney failure with replacement therapy. We computed 5-year risk ratios adjusted for age, sex, year of diagnosis, educational level, and comorbidities.

Results:

We identified 5068 patients with perioperative myocardial infarction and 137 862 patients with nonoperative myocardial infarction. The 5-year risk of all-cause mortality was 67.5% (95% CI, 66.1%–69.0%) for perioperative myocardial infarction patients and 38.0% (95% CI, 37.7%–38.3%) for nonoperative myocardial infarction patients. The adjusted risk ratio of all-cause mortality was 1.13 (95% CI, 1.11–1.16) at 5 years. After adjustment, we found no association between patients with perioperative myocardial infarction and 5-year cardiac mortality, recurrent myocardial infarction, heart failure, stroke, or kidney failure with replacement therapy when compared with nonoperative myocardial infarction patients. Perioperative myocardial infarction patients had a higher relative risk of venous thromboembolism (5-year risk ratio, 1.21 [95% CI, 1.01–1.46]) and acute kidney injury (5-year risk ratio, 1.37 [95% CI, 1.22–1.53]).

Conclusions:

Compared with nonoperative myocardial infarction patients, perioperative myocardial infarction patients had elevated risk of all-cause mortality, venous thromboembolism, and acute kidney failure. In addition to the myocardial infarction component of perioperative myocardial infarction, this poor prognosis seemed associated with the surgery or underlying comorbidities. These findings warrant further research on strategies to reduce the risk of perioperative myocardial infarction and on strategies to manage perioperative myocardial infarction.

The Coding Impact of Acute Kidney Injury in Pediatric Hospital Documentation

BACKGROUND

Acute kidney injury (AKI) increases patient morbidity and mortality. In value-based care, the documented and coded diagnoses during hospitalization influences an encounter's relative weight (RW), including severity of illness (SOI), and risk of mortality, which ultimately determines reimbursement for care. The impact of a secondary diagnosis of AKI on RW in pediatric patients has not been evaluated.

METHODS

A single-center, retrospective observational study was conducted over six months. The institutional coding database was queried for secondary diagnoses signifying AKI. The RW for each case was determined with and without an AKI secondary diagnosis. Patients were further stratified by their SOI score to evaluate change in RW and SOI.

RESULTS

Over a six-month period, 372 patients had a secondary AKI diagnosis, with a mean RW 2.14 decreasing to a mean RW 1.83 without an AKI diagnosis (p = 2.2e-16). When stratified by SOI, one patient had SOI 1 with RW change -0.286; six patients had SOI 2 with mean RW change -0.0669; 189 patients had SOI 3 with mean RW change -1.862 (p=2.23E-16); and 176 patients had SOI 4 with mean RW change -0.452 (p=9.46E-14), when the AKI secondary diagnosis was removed.

CONCLUSIONS

Significant negative changes in RW were observed when AKI was removed, suggesting diagnostic omission may result in inaccurately lesser representation of patient medical complexity and severity of illness upon hospitalization coding, which may lower reimbursement.

Clinicopathological features and short outcomes of oliguric acute tubular injury

PURPOSE

To explore the clinicopathological features and analyze the relevant risk factors and short-term renal outcomes of acute tubular injury (ATI) patients.

MATERIALS AND METHODS

A total of 83 patients with biopsy-proven ATI were included in this retrospective cohort study. Clinical characteristic and histological feature data were collected, and renal recovery at 1 month postbiopsy was recorded.

RESULTS

The severity of renal dysfunction, percentage of acute tubular lesions, interstitial inflammation and fibrosis of oliguric ATI patients were all significantly higher than those of nonoliguric patients. In the subgroup analysis of the oliguric patients, the serum creatinine and urinary microalbumin levels, severity of epithelial cell degeneration and cast formation of patients in the polyuric phase at biopsy were significantly lower than those of patients in the oliguric phase. A total of 59 patients had 1-month follow-up records, and complete renal recovery was observed in 42 patients. In the multivariate analysis, the total acute tubular injury area at biopsy was the most important independent risk factor for poor renal outcomes.

CONCLUSIONS

Oliguric ATI patients had severe clinicopathological conditions. The severity of tubular lesions seriously influenced renal function recovery, demonstrating the importance of renal biopsy in assessing the prognosis of patients with kidney disease.

NADPH oxidase family proteins: signaling dynamics to disease management

Reactive oxygen species (ROS) are pervasive signaling molecules in biological systems. In humans, a lack of ROS causes chronic and extreme bacterial infections, while uncontrolled release of these factors causes pathologies due to excessive inflammation. Professional phagocytes such as neutrophils (PMNs), eosinophils, monocytes, and macrophages use superoxide-generating NADPH oxidase (NOX) as part of their arsenal of antimicrobial mechanisms to produce high levels of ROS. NOX is a multisubunit enzyme complex composed of five essential subunits, two of which are localized in the membrane, while three are localized in the cytosol. In resting phagocytes, the oxidase complex is unassembled and inactive; however, it becomes activated after cytosolic components translocate to the membrane and are assembled into a functional oxidase. The NOX isoforms play a variety of roles in cellular differentiation, development, proliferation, apoptosis, cytoskeletal control, migration, and contraction. Recent studies have identified NOX as a major contributor to disease pathologies, resulting in a shift in focus on inhibiting the formation of potentially harmful free radicals. Therefore, a better understanding of the molecular mechanisms and the transduction pathways involved in NOX-mediated signaling is essential for the development of new therapeutic agents that minimize the hyperproduction of ROS. The current review provides a thorough overview of the various NOX enzymes and their roles in disease pathophysiology, highlights pharmacological strategies, and discusses the importance of computational modeling for future NOX-related studies.

A real-world prospective study on dialysis-requiring acute kidney injury

Background

Current information about acute kidney injury (AKI) epidemiology in developing nations derives mainly from isolated centers, with few quality multicentric epidemiological studies. Our objective was to describe a large cohort of patients with dialysis-requiring AKI derived from ordinary clinical practice within a large metropolitan area of an emerging country, assessing the impact of age and several clinical predictors on patient survival across the spectrum of human life.

Methods

We analyzed registries drawn from 170 hospitals and medical facilities in Rio de Janeiro, Brazil, in an eleven-year period (2002–2012). The study cohort was comprised of 17,158 pediatric and adult patients. Data were analyzed through hierarchical logistic regression models and mixed-effects Cox regression for survival comparison across age strata.

Results

Severe AKI was mainly hospital-acquired (72.6%), occurred predominantly in the intensive care unit (ICU) (84.9%), and was associated with multiple organ failure (median SOFA score, 11; IQR, 6–13). The median age was 75 years (IQR, 59–83; range, 0–106 years). Community-acquired pneumonia was the most frequent admission diagnosis (23.8%), and sepsis was the overwhelming precipitating cause (72.1%). Mortality was 71.6% and was higher at the age extremes. Poor outcomes were driven by age, mechanical ventilation, vasopressor support, liver dysfunction, type 1 cardiorenal syndrome, the number of failing organs, sepsis at admission, later sepsis, the Charlson score, and ICU admission. Community-acquired AKI, male gender, and pre-existing chronic kidney disease were associated with better outcomes.

Conclusions

Our study adds robust information about the real-world epidemiology of dialysis-requiring AKI with considerable clinical detail. AKI is a heterogeneous syndrome with variable clinical presentations and outcomes, including differences in the age of presentation, comorbidities, frailty state, precipitation causes, and associated diseases. In the cohort studied, AKI characteristics bore more similarities to upper-income countries as opposed to the pattern traditionally associated with resource-limited economies.

Acute Kidney Injury and Hyponatremia in Ultra-Trail Racing: A Systematic Review

Background and objectives: Ultra-trail races can cause episodes of acute kidney injury (AKI) and exercise-associated hyponatremia (EAH) in healthy subjects without previous renal pathology. This systematic review aims to review the incidence of these two syndromes together and separately taking into account the length and elevation of the ultra-trail race examined. Materials and Methods: A systematic review was conducted through electronic search in four electronic databases (PubMed, EBSCO, Web of Science and Alcorze). Results: A total of 1127 articles published between January 2006 and December 31, 2021 were included, 28 of which met the inclusion criteria. The studies were categorized according to the length and stages of the race in four categories: medium (42 to 69 km), long (70 to 99 km), extra (>100 km) and multi-stage if they included various stages. A total of 2950 runners (666 females and 2284 males) were extracted from 28 publications. The AKI incidence found was 42.04% (468 cases of 1113), and 195 of 2065 were diagnosed with EAH, accounting for 9.11%. The concurrence of both pathologies together reached 11.84% (27 individuals) from a total of 228 runners with AKI and EAH simultaneously analyzed. Sorted by race category, the AKI+EAH cases were distributed as follows: 18 of 27 in the extra (13.63% and n = 132), 4 in the large (5.79% and n = 69) and 5 in the medium category (18.15% and n = 27). Conclusions: According to these results, extra and medium races showed a similar incidence of AKI+EAH. These findings underline the importance of the duration and intensity of the race and may make them responsible for the etiology of these medical conditions. Due to their variable incidence, EAH and AKI are often underdiagnosed, leading to poorer prognosis, increased condition seriousness and hindered treatment. The results of this review urge participants, coaches and race organizers to take measures to improve the early diagnosis and urgent treatment of possible EAH and AKI cases.

Efficacy and Safety of Chuan Huang Fang Combining Reduced Glutathione in Treating Acute Kidney Injury (Grades 1-2) on Chronic Kidney Disease (Stages 2-4): Study Protocol for a Multicenter Randomized Controlled Clinical Trial

Background

Acute kidney injury (AKI) is a global public health challenge resulting in considerable morbidity and mortality. AKI on chronic kidney disease (CKD) (AKI on CKD, A on C) accounts for about a third of total AKI. For severe AKI grade 3, renal replacement therapy (RRT) should be implemented in time. However, the lack of recognized drug treatment method for AKI grades 1-2 is a crucial problem in clinic. Chuan Huang Fang (CHF) is a Chinese herbal formulation developed for the treatment of A on C from the Shanghai Municipal Hospital of Traditional Chinese Medicine. Our previous studies suggested that CHF might effectively protect renal functions of A on C patients. As a widely used antioxidant in clinic, reduced glutathione (RG) is reported to improve the clinical efficacy of high-flux hemodialysis (HFHD) in severe AKI patients recently. To address the crucial problem mentioned above, thus we design a new clinical protocol of CHF combining RG and try to evaluate the efficacy and safety of this protocol in treating patients diagnosed with CKD stages 2-4 complicated with AKI grades 1-2.

Methods

This is a multicenter randomized controlled clinical trial. We intend to enroll 162 participants, and these participants will be divided into the RG group, the CHF group, and the RG + CHF group randomly assigning 1 : 1 : 1 principle. The RG group will be general treatments combining RG, the CHF group will be general treatments combining CHF, and the RG + CHF group will be general treatments combining RG and CHF. The duration of treatment will last two weeks. The primary evaluation outcome will be the change in the slope of serum creatinine (Scr) over 2 weeks. Secondary evaluation outcomes include changes in blood urea nitrogen (BUN), estimated glomerular filtration rate (eGFR), urinary AKI biomarkers (neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), gamma-glutamyl transpeptidase (γ-GT), etc.), traditional Chinese medicine (TCM) symptoms, inflammatory indicators, and oxidative stress indicators. Meanwhile, the vital sign indicators and adverse events (AEs) will be closely observed. These dates will be meticulously recorded and properly handled by investigators throughout the study. Discussion. This study will provide convictive research-derived data to evaluate clinical efficacy and safety of CHF combing RG for CKD stages 2-4 complicated with AKI grades 1-2 and provide an evidence-based recommendation for clinicians. The timely completion of this trial will provide a novel drug treatment method for A on C. This trial is registered with ChiCTR2100043311 and registered on February 9, 2021.

Modulation of gentamicin-induced acute kidney injury by myo-inositol oxygenase via the ROS/ALOX-12/12-HETE/GPR31 signaling pathway

In this investigation, a potentially novel signaling pathway in gentamicin-induced acute kidney injury-worsened by overexpression of proximal tubular enzyme, myo-inositol oxygenase (MIOX)-was elucidated. WT, MIOX-transgenic (MIOX-Tg), and MIOX-KO mice were used. Gentamicin was administered to induce tubular injury. MIOX-Tg mice had severe tubular lesions associated with increased serum creatinine and proteinuria. Lesions were relatively mild, with no rise in serum creatinine and no albuminuria in MIOX-KO mice. Transfection of HK-2 cells with MIOX-pcDNA led to increased gentamicin-induced reactive oxygen species (ROS). Marked increase of ROS-mediated lipid hydroperoxidation was noted in MIOX-Tg mice, as assessed by 4-HNE staining. This was associated with increased expression of arachidonate 12-lipoxygenase (ALOX-12) and generation of 12-hydroxyeicosatetraenoic acid (12-HETE). In addition, notable monocyte/macrophage influx, upregulation of NF-κB and inflammatory cytokines, and apoptosis was observed in MIOX-Tg mice. Treatment of cells with ALOX-12 siRNA abolished gentamicin-mediated induction of cytokines and 12-HETE generation. HETE-12 treatment promoted this effect, along with upregulation of various signaling kinases and activation of GPCR31. Similarly, treatment of cells or mice with the ALOX-12 inhibitor ML355 attenuated inflammatory response, kinase signaling cascade, and albuminuria. Collectively, these studies highlight a potentially novel mechanism (i.e., the ROS/ALOX-12/12-HETE/GPR31 signaling axis) relevant to gentamicin-induced nephrotoxicity modulated by MIOX.

Kidney-Related Outcome in Cardiorenal Syndrome Type 3

Background and Aim. In cardiorenal syndrome (CRS) type 3, acute kidney injury (AKI) induces and, sometimes, even perpetuates acute cardiac pathologies such as arrhythmias with or without cardiac decompensation or the latter due to other causes. Epidemiological data on CRS type 3 are limited. The aim of this study was to analyze epidemiological and outcome variables in CRS type 3. Methods. A single-center, retrospective and observational trial. All subjects with positive AKI alert, treated at the University Hospital Brandenburg between January and December 2019, were evaluated. Definition of CRS type 3 was according to predefined criteria. The three endpoint categories were in-hospital death, dialysis, and recovery of kidney function. Results. A total number of 1,334 AKI alerts were screened. Finally, 95 subjects received the diagnosis CRS type 3. The survival rates were 47.1% (females) and 43.6% (males). 46.8% of affected females and 33.3% of the males required dialysis therapy. Complete recovery at the time of discharge occurred in 35.8%, and no recovery at all was found in 54.7%. Conclusions. All three predefined study endpoints, the mortality, the prevalence of dialysis, and the percentage of subjects without recovery of kidney function, were notably high. Therefore, AKI patients with imminent or established cardiac complications require the highest attention of nephrologists in charge.

Real-world Health Data and Precision for the Diagnosis of Acute Kidney Injury, Acute-on-Chronic Kidney Disease, and Chronic Kidney Disease: Observational Study

Background

The criteria for the diagnosis of kidney disease outlined in the Kidney Disease: Improving Global Outcomes guidelines are based on a patient’s current, historical, and baseline data. The diagnosis of acute kidney injury, chronic kidney disease, and acute-on-chronic kidney disease requires previous measurements of creatinine, back-calculation, and the interpretation of several laboratory values over a certain period. Diagnoses may be hindered by unclear definitions of the individual creatinine baseline and rough ranges of normal values that are set without adjusting for age, ethnicity, comorbidities, and treatment. The classification of correct diagnoses and sufficient staging improves coding, data quality, reimbursement, the choice of therapeutic approach, and a patient’s outcome.

Objective

In this study, we aim to apply a data-driven approach to assign diagnoses of acute, chronic, and acute-on-chronic kidney diseases with the help of a complex rule engine.

Methods

Real-time and retrospective data from the hospital’s clinical data warehouse of inpatient and outpatient cases treated between 2014 and 2019 were used. Delta serum creatinine, baseline values, and admission and discharge data were analyzed. A Kidney Disease: Improving Global Outcomes–based SQL algorithm applied specific diagnosis-based International Classification of Diseases (ICD) codes to inpatient stays. Text mining on discharge documentation was also conducted to measure the effects on diagnosis.

Results

We show that this approach yielded an increased number of diagnoses (4491 cases in 2014 vs 11,124 cases of ICD-coded kidney disease and injury in 2019) and higher precision in documentation and coding. The percentage of unspecific ICD N19-coded diagnoses of N19 codes generated dropped from 19.71% (1544/7833) in 2016 to 4.38% (416/9501) in 2019. The percentage of specific ICD N18-coded diagnoses of N19 codes generated increased from 50.1% (3924/7833) in 2016 to 62.04% (5894/9501) in 2019.

Conclusions

Our data-driven method supports the process and reliability of diagnosis and staging and improves the quality of documentation and data. Measuring patient outcomes will be the next step in this project.

Acute renal injury events in diabetic patients treated with SGLT2 inhibitors: A comprehensive review with a special reference to RAAS blockers

Renin-angiotensin-aldosterone system (RAAS) blockers and sodium-glucose cotransporter type 2 inhibitors (SGLT2is) are two pharmacological classes that proved a remarkable nephroprotective effect, yet a risk of acute kidney injury (AKI) was also pointed out. In 2016, the US Food and Drug Administration recommended caution with the concomitant use of these medications. While the literature devoted to RAAS blockers remained surprisingly limited, numerous articles were published in recent years with SGLT2is. Safety analyses of large prospective cardiorenal trials showed a reduced rather than an increased number of AKI events in patients with type 2 diabetes treated with SGLT2is compared with those treated with placebo, despite the fact that a majority of patients received RAAS blockers at baseline. Interestingly, retrospective observational studies confirmed these reassuring findings in real-life conditions in more heterogeneous and possibly more frailty populations also commonly treated with RAAS blockers by showing a reduced risk of AKI with SGLT2is compared with other glucose-lowering drugs. Currently, there are no evidence of an increased risk of AKI with RAAS blocker-SGLT2i combinations in absence of haemodynamic instability. Several underlying mechanisms could explain a decreased rather than an increased risk of AKI with SGLT2is, including in patients treated with RAAS blockers.

Association of persistent acute kidney injury and renal recovery with mortality in hospitalised patients

Objectives

Acute kidney injury (AKI) affects up to one-quarter of hospitalised patients and 60% of patients in the intensive care unit (ICU). We aim to understand the baseline characteristics of patients who will develop distinct AKI trajectories, determine the impact of persistent AKI and renal non-recovery on clinical outcomes, resource use, and assess the relative importance of AKI severity, duration and recovery on survival.

Methods

In this retrospective, longitudinal cohort study, 156 699 patients admitted to a quaternary care hospital between January 2012 and August 2019 were staged and classified (no AKI, rapidly reversed AKI, persistent AKI with and without renal recovery). Clinical outcomes, resource use and short-term and long-term survival adjusting for AKI severity were compared among AKI trajectories in all cohort and subcohorts with and without ICU admission.

Results

Fifty-eight per cent (31 500/54 212) had AKI that rapidly reversed within 48 hours; among patients with persistent AKI, two-thirds (14 122/22 712) did not have renal recovery by discharge. One-year mortality was significantly higher among patients with persistent AKI (35%, 7856/22 712) than patients with rapidly reversed AKI (15%, 4714/31 500) and no AKI (7%, 22 117/301 466). Persistent AKI without renal recovery was associated with approximately fivefold increased hazard rates compared with no AKI in all cohort and ICU and non-ICU subcohorts, independent of AKI severity.

Discussion

Among hospitalised, ICU and non-ICU patients, persistent AKI and the absence of renal recovery are associated with reduced long-term survival, independent of AKI severity.

Conclusions

It is essential to identify patients at risk of developing persistent AKI and no renal recovery to guide treatment-related decisions.

Advances in artificial intelligence and deep learning systems in ICU-related acute kidney injury

PURPOSE OF REVIEW

Acute kidney injury (AKI) affects nearly 60% of all patients admitted to ICUs. Large volumes of clinical, monitoring and laboratory data produced in ICUs allow the application of artificial intelligence analytics. The purpose of this article is to assimilate and critically evaluate recently published literature regarding artificial intelligence applications for predicting, diagnosing and subphenotyping AKI among critically ill patients.

RECENT FINDINGS

Among recent studies regarding artificial intelligence implementations for predicting, diagnosing and subphenotyping AKI among critically ill patients, there are many promising models, but few had external validation, clinical interpretability and high predictive performance. Deep learning techniques leveraging multimodal clinical data show great potential to provide continuous, accurate, early predictions of AKI risk, which could be implemented clinically to optimize preventive and early therapeutic management strategies.

SUMMARY

Use of consensus criteria, standard definitions and common data models could facilitate access to machine learning-ready data sets for external validation. The lack of interpretability, explainability, fairness and transparency of artificial intelligence models hinder their entrustment and clinical implementation; compliance with standardized reporting guidelines can mitigate these challenges.

A deep-learning model to continuously predict severe acute kidney injury based on urine output changes in critically ill patients

BACKGROUND

Acute Kidney Injury (AKI), a frequent complication of pateints in the Intensive Care Unit (ICU), is associated with a high mortality rate. Early prediction of AKI is essential in order to trigger the use of preventive care actions.

METHODS

The aim of this study was to ascertain the accuracy of two mathematical analysis models in obtaining a predictive score for AKI development. A deep learning model based on a urine output trends was compared with a logistic regression analysis for AKI prediction in stages 2 and 3 (defined as the simultaneous increase of serum creatinine and decrease of urine output, according to  the Acute Kidney Injury Network (AKIN) guidelines). Two retrospective datasets including 35,573 ICU patients were analyzed. Urine output data were used to train and test the logistic regression and the deep learning model.

RESULTS

The deep learning model defined an area under the curve (AUC) of 0.89 (± 0.01), sensitivity = 0.8 and specificity = 0.84, which was higher than the logistic regression analysis. The deep learning model was able to predict 88% of AKI cases more than 12 h before their onset: for every 6 patients identified as being at risk of AKI by the deep learning model, 5 experienced the event. On the contrary, for every 12 patients not considered to be at risk by the model, 2 developed AKI.

CONCLUSION

In conclusion, by using urine output trends, deep learning analysis was able to predict AKI episodes more than 12 h in advance, and with a higher accuracy than the classical urine output thresholds. We suggest that this algorithm could be integrated in the ICU setting to better manage, and potentially prevent, AKI episodes.

Androgen deprivation therapy and acute kidney injury in patients with prostate cancer undergoing definitive radiotherapy

BACKGROUND

Androgen deprivation therapy (ADT) is frequently utilized in conjunction with radiotherapy (RT) in the definitive management of prostate cancer. Prior studies have suggested an association between ADT use and acute kidney injury (AKI), however, these included heterogeneous populations undergoing a variety of treatments and relied on billing codes to ascertain the incidence of AKI.

METHODS

We analyzed a cohort of 27,868 veterans undergoing definitive RT + /- ADT for prostate cancer between 2001 and 2015 using the Veterans Affairs Informatics and Computing Infrastructure (VINCI). Exposure was defined as use of ADT within one year of diagnosis. The primary outcome was AKI, defined by an increase in serum creatinine to at least 1.5 times the baseline value. AKIs were classified as mild, moderate, or severe in accordance with international guidelines. A multivariate competing risks model was used to account for demographic and oncologic factors as well as medications and procedures known to influence the risk of AKI.

RESULTS

Most (n = 18,754) men received RT alone; 9,114 men received RT + ADT. The incidence of AKI at two years after diagnosis was 10.5% in the RT + ADT group and 7.9% in the RT group (Gray's test p < 0.01). Multivariate analysis confirmed ADT usage was associated with an increased risk for any AKI (SHR = 1.24, 95% CI = 1.14-1.36, p < 0.01). ADT was also associated with an increased risk of mild AKI (SHR = 1.13, 95% CI = 1.01-1.27, p = 0.04) and moderate AKI (SHR = 1.45, 95% CI = 1.20-1.76, p < 0.01), though not severe AKI (SHR = 1.33, 95% CI = 0.93-1.91, p = 0.11).

CONCLUSIONS

Our findings confirm that use of ADT is associated with an increased risk of AKI in patients undergoing definitive RT for prostate cancer. Clinicians should be alert to the potential for renal dysfunction in this population.

The Kynurenine Pathway in Acute Kidney Injury and Chronic Kidney Disease

BACKGROUND

The kynurenine pathway (KP) is the major catabolic pathway for tryptophan degradation. The KP plays an important role as the sole de novo nicotinamide adenine dinucleotide (NAD+) biosynthetic pathway in normal human physiology and functions as a counter-regulatory mechanism to mitigate immune responses during inflammation. Although the KP has been implicated in a variety of disorders including Huntington's disease, seizures, cardiovascular disease, and osteoporosis, its role in renal diseases is seldom discussed.

SUMMARY

This review summarizes the roles of the KP and its metabolites in acute kidney injury (AKI) and chronic kidney disease (CKD) based on current literature evidence. Metabolomics studies demonstrated that the KP metabolites were significantly altered in patients and animal models with AKI or CKD. The diagnostic and prognostic values of the KP metabolites in AKI and CKD were highlighted in cross-sectional and longitudinal human observational studies. The biological impact of the KP on the pathophysiology of AKI and CKD has been studied in experimental models of different etiologies. In particular, the activation of the KP was found to confer protection in animal models of glomerulonephritis, and its immunomodulatory mechanism may involve the regulation of T cell subsets such as Th17 and regulatory T cells. Manipulation of the KP to increase NAD+ production or diversion toward specific KP metabolites was also found to be beneficial in animal models of AKI. Key Messages: KP metabolites are reported to be dysregulated in human observational and animal experimental studies of AKI and CKD. In AKI, the magnitude and direction of changes in the KP depend on the etiology of the damage. In CKD, KP metabolites are altered with the onset and progression of CKD all the way to advanced stages of the disease, including uremia and its related vascular complications. The activation of the KP and diversion to specific sub-branches are currently being explored as therapeutic strategies in these diseases, especially with regards to the immunomodulatory effects of certain KP metabolites. Further elucidation of the KP may hold promise for the development of biomarkers and targeted therapies for these kidney diseases.