Acute kidney injury in elderly patients: narrative review on incidence, risk factors, and mortality

Characteristics and preventability of medication-related admissions for acute kidney injury and dehydration in elderly patients

PURPOSE

Patients with impaired renal function using medication that affects glomerular filtration rate are at increased risk of developing acute kidney injury (AKI) leading to hospital admissions. The risk increases during periods of dehydration due to diarrhoea, vomiting or fever (so-called "sick days"), or high environmental temperatures (heat wave). This study aims to gain insight into the characteristics and preventability of medication-related admissions for AKI and dehydration in elderly patients.

METHODS

Retrospective case series study in patients aged ≥ 65 years with admission for acute kidney injury, dehydration or electrolyte imbalance related to dehydration that was defined as medication-related. General practitioner's (GP) patient records including medication history and hospital discharge letters were available. For each admission, patient and admission characteristics were collected to review the patient journey. A case-by-case assessment of preventability of hospital admissions was performed.

RESULTS

In total, 75 admissions were included. Most prevalent comorbidities were hypertension, diabetes, and known impaired renal function. Diuretics and RAS-inhibitors were the most prevalent medication combination. Eighty percent of patients experienced non-acute onset of symptoms and 60% had contacted their GP within 2 weeks prior to admission. Around 40% (n = 29) of admissions were considered potentially preventable if pharmacotherapy had been timely and adequately adjusted.

CONCLUSION

A substantial proportion of patients admitted with AKI or dehydration experience non-acute onset of symptoms and had contacted their GP within 2 weeks prior to admission. Timely adjusting of medication in these patients could have potentially prevented a considerable number of admissions.

Tumour lysis syndrome

Tumour lysis syndrome (TLS) represents a critical oncological emergency characterized by extensive tumour cell breakdown, leading to the swift release of intracellular contents into the systemic circulation, outpacing homeostatic mechanisms. This process results in hyperuricaemia (a by-product of intracellular DNA release), hyperkalaemia, hyperphosphataemia, hypocalcaemia and the accumulation of xanthine. These electrolyte and metabolic imbalances pose a significant risk of acute kidney injury, cardiac arrhythmias, seizures, multiorgan failure and, rarely, death. While TLS can occur spontaneously, it usually arises shortly after the initiation of effective treatment, particularly in patients with a large cancer cell mass (defined as ≥500 g or ≥300 g/m2 of body surface area in children). To prevent TLS, close monitoring and hydration to improve renal perfusion and urine output and to minimize uric acid or calcium phosphate precipitation in renal tubules are essential. Intervention is based on the risk of a patient of having TLS and can include rasburicase and allopurinol. Xanthine, typically enzymatically converted to uric acid, can accumulate when xanthine oxidases, such as allopurinol, are administered during TLS management. Whether measurement of xanthine is clinically useful to optimize the use of allopurinol or rasburicase remains to be determined.

Renal and patient outcomes of emergency hemodialysis in elderly individuals: a retrospective cohort study

PURPOSE

The aging population, commonly defined as individuals aged 65 and above, faces an increased risk of kidney-related diseases. This study investigates emergency dialysis in the elderly population, focusing on indications, clinical and laboratory findings, renal status, and mortality rates.

METHODS

The data of 442 elderly patients (≥ 65 years old) who underwent emergency dialysis at a tertiary university hospital were retrospectively examined. Demographics, comorbidities, emergency dialysis indications, clinical presentation, method, complications, pre/post-dialysis status, and follow-up were assessed.

RESULTS

74.9% of the patients had a history of chronic kidney disease (CKD). Emergency dialysis was mainly initiated due to hypervolemia (43.7%) and uremic symptoms (29.2%). Hypotension was the most common dialysis-related complication (34.4%). The mortality rate was 34.6%; among the survivors, 15.2% achieved complete renal recovery, while 32.5% and 52.3% developed dialysis-independent and -dependent CKD, respectively. In multivariate analysis, blood urea, serum sodium, mean arterial pressure, dyspnea, tachypnea, and tachycardia on admission were found to be associated with mortality.

CONCLUSION

Our study provides insights into emergency dialysis challenges in the elderly population, emphasizing the need for personalized interventions and further research to improve care and outcomes in this growing demographic.

A nomogram for predicting 28-day mortality in elderly patients with acute kidney injury receiving continuous renal replacement therapy: a secondary analysis based on a retrospective cohort study

BACKGROUND

Acute kidney injury (AKI) is a common and serious condition, particularly among elderly patients. It is associated with high morbidity and mortality rates, further compounded by the need for continuous renal replacement therapy in severe cases. To improve clinical decision-making and patient management, there is a need for accurate prediction models that can identify patients at a high risk of mortality.

METHODS

Data were extracted from the Dryad Digital Repository. Multivariate analysis was performed using least absolute shrinkage and selection operator (LASSO) logistic regression analysis to identify independent risk factors and construct a predictive nomogram for mortality within 28 days after continuous renal replacement therapy in elderly patients with acute kidney injury. The discrimination of the model was evaluated in the validation cohort using the area under the receiver operating characteristic curve (AUC), and calibration was evaluated using a calibration curve. The clinical utility of the model was assessed using decision curve analysis (DCA).

RESULTS

A total of 606 participants were enrolled and randomly divided into two groups: a training cohort (n = 424) and a validation cohort (n = 182) in a 7:3 proportion. A risk prediction model was developed to identify independent predictors of 28-day mortality in elderly patients with AKI. The predictors included age, systolic blood pressure, creatinine, albumin, phosphorus, age-adjusted Charlson Comorbidity Index (CCI), Acute Physiology and Chronic Health Evaluation II (APACHE II) score, and sequential organ failure assessment (SOFA) score. These predictors were incorporated into a logistic model and presented in a user-friendly nomogram. In the validation cohort, the model demonstrated good predictive performance with an AUC of 0.799. The calibration curve showed that the model was well calibrated. Additionally, DCA revealed significant net benefits of the nomogram for clinical application.

CONCLUSION

The development of a nomogram for predicting 28-day mortality in elderly patients with AKI receiving continuous renal replacement therapy has the potential to improve prognostic accuracy and assist in clinical decision-making.

Clinical Profile and Short-Term Outcomes of Acute Kidney Injury in Elderly Patients in a Tertiary Care Center

Background Acute kidney injury (AKI) is a common and serious condition affecting elderly patients. Despite its significance, comprehensive research focusing specifically on the clinical profile and short-term outcomes of AKI in this vulnerable population is lacking. Objective This study aimed to evaluate the clinical profile and short-term outcomes of AKI in elderly patients admitted to a tertiary care center. Methods A prospective observational study was conducted from December 2023 to March 2024, involving 75 elderly patients (aged ≥65 years) diagnosed with AKI. Baseline demographic data, clinical profiles, laboratory investigations, mortality rate among elderly patients diagnosed with AKI within 30 days of diagnosis, and short-term outcomes were recorded and analyzed. Descriptive statistics and appropriate statistical tests were used for the data analysis. Results The study cohort had a mean age of 72.6 years. Hypertension was present in 55 patients (73.3%), and diabetes mellitus was observed in 30 patients (40.0%). Prerenal causes of AKI were identified in 40 patients (53.3%), while acute tubular necrosis was found in 25 patients (33.3%). Stage 2 AKI was the most common, affecting 35 patients (46.7%). Out of the 75 patients, 15 patients (20.0%) succumbed to AKI within the study period. Deceased patients had longer hospital stays, with a median of 16 days compared to 10 days for survivors. ICU admission was required for 13 of the deceased patients (86.7%), compared to 32 of the surviving patients (53.3%). The need for renal replacement therapy was higher among the deceased patients, with 11 out of 15 patients (73.3%) requiring it, compared to 19 out of 60 surviving patients (31.7%). Renal function recovery was notably lower in the deceased patients. Conclusion AKI in elderly patients was associated with significant morbidity and mortality, highlighting the need for early recognition, appropriate management, and preventive strategies. A comprehensive evaluation of the clinical profile and short-term outcomes of AKI in the elderly population provides valuable insights for optimizing patient care and improving outcomes.

Development and validation of a medication-based risk prediction model for acute kidney injury in older outpatients

BACKGROUND

Older adults are at an increased risk of acute kidney injury (AKI), particularly in community settings, often due to medications. Effective prevention hinges on identifying high-risk patients, yet existing models for predicting AKI risk in older outpatients are scarce, particularly those incorporating medication variables. We aimed to develop an AKI risk prediction model that included medication-related variables for older outpatients.

METHODS

We constructed a cohort of 2,272,257 outpatients aged ≥65 years using a national claims database. This cohort was split into a development (70%) and validation (30%) groups. Our primary goal was to identify newly diagnosed AKI within one month of cohort entry in an outpatient context. We screened 170 variables and developed a risk prediction model using logistic regression.

RESULTS

The final model integrated 12 variables: 2 demographic, 4 comorbid, and 6 medication-related. It showed good performance with acceptable calibration. In the validation cohort, the area under the receiver operating characteristic curve value was 0.720 (95% confidence interval, 0.692-0.748). Sensitivity and specificity were 69.9% and 61.9%, respectively. Notably, the model identified high-risk patients as having a 27-fold increased AKI risk compared with low-risk individuals.

CONCLUSION

We have developed a new AKI risk prediction model for older outpatients, incorporating critical medication-related variables with good discrimination. This tool may be useful in identifying and targeting patients who may require interventions to prevent AKI in an outpatient setting.

Characterization of Demographic, Clinical, and Laboratory Risk Factors for Stroke in a Tertiary Hospital in Riyadh, Saudi Arabia

Background Stroke is a major cause of death and long-term disability worldwide, with varying incidence and risk factors across different populations. This study aims to analyze demographic, clinical, and laboratory risk factors for stroke among the Saudi Arabian population to enhance the understanding of its behavior and associated mortality. Methods In this retrospective cohort study, we analyzed data from 3586 patients diagnosed with hemorrhagic or non-hemorrhagic stroke at King Fahad Medical City from January 1, 2020, to November 11, 2022. We collected data on demographic variables, past medical history, social history, nationality, and laboratory components. Statistical analyses were performed using IBM SPSS Statistics for Windows, Version 27.0. (Armonk, NY: IBM Corp.), with significance set at p<0.05. Results The study population was predominantly male (57.86%) and within the age group of 51 to 80 years (58.8%). A significant portion of patients were Saudi nationals (99.6%), with hypertension (50.2%) and diabetes (40.4%) being the most common comorbidities. Laboratory abnormalities related to sodium and potassium levels were strongly linked to mortality rates. Notably, ischemic stroke was the most common type across all age groups, except for patients under age 16, where hemorrhagic stroke was more prevalent. Conclusions Our findings reveal significant associations between stroke risk factors and mortality within the Saudi Arabian population, highlighting the impact of hypertension, diabetes, and electrolyte imbalances. The study underscores the need for targeted stroke prevention and management strategies in Saudi Arabia, aligning with global trends to mitigate the burden of this disease.

Antibiotic-Associated Acute Kidney Injury Among Older Adults: A Case-Crossover Study

BACKGROUND AND OBJECTIVES

Drug-related acute kidney injury is quite common in older adults. The associated drugs, including antibiotics, are often co-prescribed. The objective of this study was to ascertain antibiotic-associated acute kidney injury (AKI) in older adults aged 65 years or above in New Zealand using a case-crossover study design.

METHODS

The International Statistical Classification of Diseases and Related Health Problems, tenth revision, Australian modification code N17.x was used to identify all individuals aged 65 years and above with a diagnosis of incident AKI on admission between 1 January 2005 and 31 December 2020, from the New Zealand National Minimum Data Set. A case-crossover cohort for antibiotic exposures, with a 3 day case period and two 30 day washout periods, summed up to a 66 day study period, was created. Using conditional logistic regression, the changed odds of AKI due to exposure to an antibiotic was calculated as matched odds ratios and their 95% confidence intervals.

RESULTS

A total of 2399 incident cases of AKI were identified between 2005 and 2020 among older adults. The adjusted odds of consuming sulfamethoxazole/trimethoprim antibiotic during the case period was 3.57 times (95% CI 2.86-4.46) higher than the reference period among the incident AKI cases. Fluoroquinolone utilization was also associated with incident AKI (adjusted OR = 2.56; 95% CI 1.90-3.46).

CONCLUSION

The potential of sulfamethoxazole/trimethoprim and fluoroquinolones to be associated with AKI raises the significant need for vigilant prescribing of these antibiotics in older adults.

Mortality Analysis in Geriatric Patients With Acute Kidney Injury Admitted in the Intensive Care Unit: A Single-Center Cross-Sectional Study

Introduction Acute kidney injury (AKI) is an abrupt reduction in kidney function that causes nitrogenous waste and other waste products to be retained. Methods This cross-sectional study was conducted from February 2015 to January 2016. The study received approval from the Independent Ethics Committee, which included patients over 60 with AKI. The study duration was 12 consecutive months to ascertain the etiology, severity, and hospital outcomes of AKI. Results The common etiologies of AKI included drug-induced (25%), age-related (21.67%), cardiac (13.33%), respiratory (20%), tropical (15%), and pancreatitis (15%) cases. Another predominant etiology observed was obstructive nephropathy (55%), with the highest (37.5%) mortality rate. The distribution of patients based on KDIGO criteria showed no significant difference in mortality percentages among classes (p=0.177). Conservative management without renal replacement therapy was the most common approach to treat AKI, with a 39% mortality rate. Conclusion Among different causes of AKI in the geriatric age group, drug-induced AKI, and obstructive nephropathy were predominantly associated with hospital mortality.

LncRNA 152 attenuates lipopolysaccharide-induced acute kidney injury in rats by regulating the FGF23/Klotho/MAPK axis

AIM

This study aimed to explore the effect and related mechanisms of LncRNA 152 in acute kidney injury (AKI).

METHODS

QRT-PCR was used to detect the expression of LncRNA 152, FGF23 and Klotho in the serum of patients with AKI. Subsequently, Sprague Dawley (SD) rats were induced into AKI animal model by lipopolysaccharide (LPS). Then, H&E staining was performed to observe the pathological changes in the rat kidney tissues; qRT-PCR to detect the expression of LncRNA 152, FGF23 and Klotho in the rat kidney tissues; biochemical assay and ELISA to assess the levels of renal function indexes and inflammatory factors in rat serum, as well as oxidative stress indexes in kidney tissues; and western blot to measure the protein expressions of FGF23, Klotho, p-p38 and p38 in rat kidney tissues.

RESULTS

LncRNA 152 was significantly down-regulated in serum of AKI patients and kidney tissues of AKI rats. In AKI patients, LncRNA 152 was negatively correlated with FGF23 expression while positively correlated with Klotho expression. LncRNA 152 overexpression reduced the levels of blood urea nitrogen (BUN), creatinine (Cr) and cystatin C (Cys-C) and inflammatory factors in serum of AKI rats and attenuated pathological damage and oxidative stress of kidney tissues. In addition, LncRNA 152 overexpression also decreased FGF23 expression and p-p38/p38 ratio while up-regulated Klotho expression in the kidney tissues of AKI rats.

CONCLUSION

LncRNA 152 attenuates oxidative stress and inflammatory responses by regulating the FGF23/Klotho axis and inhibiting the MAPK signalling pathway in rat kidney tissues, thereby ameliorating LPS-induced AKI.

Renal function in very old critically ill patients

PURPOSE OF REVIEW

Current demographic change leads to higher number of elderly patients admitted to an ICU. Among other organs also the kidneys show age-related changes, which are associated with a decline in various aspects of renal function. The purpose of this review is to provide an overview of structural and functional changes in elderly and also to specifically address the increased risk of acute kidney injury (AKI) in this population.

RECENT FINDINGS

Ageing in the kidneys is affected by many different factors, such as low grade chronic inflammation, called inflammageing, and various comorbidities. Nevertheless, a decrease of glomerular filtration rate (GFR) occurs independent of the presence of comorbidities and a steady decline of GFR has been reported in both healthy men and women. Pharmacodynamic of many drugs is altered by these changes. Additionally the rate of diuretic resistance appears to be increased. The cause of AKI occurrence in older age is, multifactorial and includes preventable triggers (hypovolemia, hypotension, nephrotoxins) as well as changes associated with aging.

SUMMARY

Age-related alterations of the kidneys were found at microscopic and macroscopic levels of the cell. These changes lead to a reduced renal reserve and subsequently to an increased vulnerability of aged kidneys when an additional stressor is added. Age is an independent risk factor for developing AKI. Physicians should take into account the altered renal function in elderly patients and take renal protective measures at an early stage.

Incidence of hospital-acquired acute kidney injury and trajectories of glomerular filtration rate in older adults

BACKGROUND

In older adults, epidemiological data on incidence rates (IR) of hospital-acquired acute kidney injury (AKI) are scarce. Also, little is known about trajectories of kidney function before hospitalization with AKI.

METHODS

We used data from biennial face-to-face study visits from the prospective Berlin Initiative Study (BIS) including community-dwelling participants aged 70+ with repeat estimated glomerular filtration rate (eGFR) based on serum creatinine and cystatin C. Primary outcome was first incident of hospital-acquired AKI assessed through linked insurance claims data. In a nested case-control study, kidney function decline prior to hospitalization with and without AKI was investigated using eGFR trajectories estimated with mixed-effects models adjusted for traditional cardiovascular comorbidities.

RESULTS

Out of 2020 study participants (52.9% women; mean age 80.4 years) without prior AKI, 383 developed a first incident AKI, 1518 were hospitalized without AKI, and 119 were never hospitalized during a median follow-up of 8.8 years. IR per 1000 person years for hospital-acquired AKI was 26.8 (95% confidence interval (CI): 24.1-29.6); higher for men than women (33.9 (29.5-38.7) vs. 21.2 (18.1-24.6)). IR (CI) were lowest for persons aged 70-75 (13.1; 10.0-16.8) and highest for ≥ 90 years (54.6; 40.0-72.9). eGFR trajectories declined more steeply in men and women with AKI compared to men and women without AKI years before hospitalization. These differences in eGFR trajectories remained after adjustment for traditional comorbidities.

CONCLUSION

AKI is a frequent in-hospital complication in individuals aged 70 + showing a striking increase of IR with age. eGFR decline was steeper in elderly patients with AKI compared to elderly patients without AKI years prior to hospitalization emphasising the need for long-term kidney function monitoring pre-admission to improve risk stratification.

Exploiting Machine Learning Technologies to Study the Compound Effects of Serum Creatinine and Electrolytes on the Risk of Acute Kidney Injury in Intensive Care Units

Assessing the risk of acute kidney injury (AKI) has been a challenging issue for clinicians in intensive care units (ICUs). In recent years, a number of studies have been conducted to investigate the associations between several serum electrolytes and AKI. Nevertheless, the compound effects of serum creatinine, blood urea nitrogen (BUN), and clinically relevant serum electrolytes have yet to be comprehensively investigated. Accordingly, we initiated this study aiming to develop machine learning models that illustrate how these factors interact with each other. In particular, we focused on ICU patients without a prior history of AKI or AKI-related comorbidities. With this practice, we were able to examine the associations between the levels of serum electrolytes and renal function in a more controlled manner. Our analyses revealed that the levels of serum creatinine, chloride, and magnesium were the three major factors to be monitored for this group of patients. In summary, our results can provide valuable insights for developing early intervention and effective management strategies as well as crucial clues for future investigations of the pathophysiological mechanisms that are involved. In future studies, subgroup analyses based on different causes of AKI should be conducted to further enhance our understanding of AKI.

Impaired NRF2 Inhibits Recovery from Ischemic Reperfusion Injury in the Aging Kidney

Deteriorating kidney function is frequently observed in the elderly population, as well as vulnerability to acute kidney failure, such as ischemic/reperfusion injury (IRI), and inadequate recovery from IRI is one of the mechanisms of kidney dysfunction in the elderly. The potential mediators in the progression of kidney dysfunction in the aging kidney have not yet been clearly revealed. In this study, we investigated the role of nuclear factor erythroid 2-related factor 2 (NRF2), which is an essential regulator of cellular redox homeostasis, in restoring kidney function after IRI in the aging kidney. NRF2 expression decreased significantly in the kidneys of old mice, as well as histologic and functional renal recovery after IRI; 45-min renal pedicle clamping was retarded in old compared with young mice. Persistent renal injury during the recovery phase after IRI was aggravated in NRF2 knockout (KO) mice compared to wild-type mice. Oxidative stress occurred in NRF2 KO old mice during the IRI recovery phase along with decreased expression of mitochondrial OXPHOS-related proteins and a reduction in mitochondrial ATP content. In vitro, hypoxia/reoxygenation (H/R) injury was aggravated in senescent human proximal tubuloepithelial cells after NRF2 restriction using NRF2 siRNA, which also increased the level of oxidative stress and deteriorated mitochondrial dysfunction. Treating the mice with an NRF2 activator, CDDO-Me, alleviated the injury. These results suggest that NRF2 may be a therapeutic target for the aging kidney.

Advances of perioperative acute kidney injury in elderly patients undergoing non-cardiac surgery

The risk of developing perioperative acute kidney injury (AKI) in elderly patients increases with age. The combined involvement of aging kidneys, coexisting multiple underlying chronic diseases, and increased exposure to potential renal stressors and nephrotoxic drugs or invasive procedures constitute susceptibility factors for AKI in elderly patients. The perioperative AKI in elderly patients undergoing noncardiac surgery has its own specific population characteristics, so it is necessary to further explore the characteristics of AKI in elderly patients in terms of epidemiology, clinical diagnosis, risk factors, and preventive and curative measures to provide meaningful clinical advice to improve prognosis, accelerate recovery, and reduce medical burden in elderly patients. Since AKI has the fastest-growing incidence in older patients and is associated with a worse prognosis, early detection, early diagnosis, and prevention of AKI are important for elderly patients in the perioperative period. Large, multicenter, randomized controlled clinical studies in elderly non-cardiac surgery patients with AKI can be conducted in the future, with the aim of providing the evidence to reduce of the incidence of AKI and to improve the prognosis of patients.

Incidence, risk factors and outcomes of acute kidney injury in surgical intensive care unit octogenarians at the Jordan University Hospital

BACKGROUND

Acute kidney damage (AKI) is among the most severe consequences observed in surgical intensive care units (SICUs). We aim to observe the incidence, risk factors, and outcomes of acute kidney injury in SICU octogenarians.

METHODS

A cross-sectional retrospective study was conducted at the SICU of Jordan University Hospital (JUH), a tertiary teaching hospital in a developing country, between January 2018 and December 2019. Patients who were 80 years or older at the time of data collection were included. The definition of AKI was based on Kidney Disease Improving Global Outcomes (KDIGO) criteria. Demographic, clinical, and laboratory data were reviewed.

RESULTS

A total number of 168 patients were included. The mean age was 84.0 ± 3.8 years, and 54.8% of the participants were women. Of those, 115 (68.5%) had surgery before or during ICU stay, and 28.7% of the patients' surgeries were an emergency surgery. Also, 47.8% of surgeries were considered by anesthesia to be high-risk surgeries. A total of 55 patients (32.7%) developed AKI during their SICU stay. The factors that were significantly associated with AKI in the ICU patients included use of beta blocker [AOR: 3.7; 95% CI: 1.2-11.8; p = 0.025], and inotropes [AOR:4.0; 95% CI: 1.2-13.3; p = 0.03]. The factors that were significantly associated with mortality in the ICU included using mechanical ventilation [AOR:18.7; 95% CI: 2.4-141.9; p = 0.005] and inotropes use [AOR: 12.3; 95% CI: 1.2-120.7; p = 0.031].

CONCLUSIONS

The incidence of AKI during SICU stay in this study was 32.7% and it was significantly associated with the use of beta blockers, mechanical ventilation, and inotropes. The mortality rate among octogenarians who developed AKI during SICU stay was 36.4%. Further studies are needed globally to assess the incidence of AKI in octogenarian surgical patients and identify risk factors to provide preventative measurements and strategies.

Incidence, predictors, clinical outcomes, and economic burden of recurrent acute kidney injury: a retrospective cohort study

OBJECTIVE

This study aimed to assess the incidence, predictors, mortality, and economic outcomes of recurrent Acute kidney injury (AKI) in Jordan.

METHODS

This was a retrospective cohort study that included adult patients who were admitted with AKI to university hospitals in the country from 2010-2019. Recurrent episodes of AKI, laboratory data, baseline medication list, and death dates were retrieved from patient's medical records. The incidence rate of recurrent AKI was estimated. Predictors of recurrent AKI and mortality during the five years post-discharge was evaluated. Total admission charges were described and evaluated in total and by service provided.

RESULTS

Among 1162 AKI patients, 57 patients (4.9%) died during the index admission (first admission during the study period), and among the survivors, 220 patients were re-hospitalized with a recurrent AKI during five years of follow-up. Patients with higher discharge serum creatinine level (SCr) at index admission had higher odds of AKI recurrence (OR = 1.001). Patients who were on respiratory, antineoplastic, or anticoagulant medications were also more susceptible to recurrence; ORs were 1.69, 2.77, and 4.16, respectively. Patients who were elderly, with recurrent AKI episodes, or with a more extended hospital stay at index admission were more likely to die during the five years post discharge. The median charge of recurrent admissions was higher than the median charge of the index admissions; 1519.17 JOD ($2142.7) versus 1362.85 JOD ($1922.2), respectively.

CONCLUSIONS

Recurrent AKI is associated with increased mortality and health expenditures. Higher discharge SCr levels at index admission, and chronic comorbidities are associated with a higher likelihood of AKI recurrence.

The Role of CD38 in the Pathogenesis of Cardiorenal Metabolic Disease and Aging, an Approach from Basic Research

Aging is a major risk factor for the leading causes of mortality, and the incidence of age-related diseases including cardiovascular disease, kidney disease and metabolic disease increases with age. NAD⁺ is a classic coenzyme that exists in all species, and that plays a crucial role in oxidation-reduction reactions. It is also involved in the regulation of many cellular functions including inflammation, oxidative stress and differentiation. NAD⁺ declines with aging in various organs, and the reduction in NAD⁺ is possibly involved in the development of age-related cellular dysfunction in cardiorenal metabolic organs through the accumulation of inflammation and oxidative stress. Levels of NAD⁺ are regulated by the balance between its synthesis and degradation. CD38 is the main NAD⁺-degrading enzyme, and CD38 is activated in response to inflammation with aging, which is associated with the reduction in NAD⁺ levels. In this review, focusing on CD38, we discuss the role of CD38 in aging and the pathogenesis of age-related diseases, including cardiorenal metabolic disease.

Seasonal pattern in elderly hospitalized with acute kidney injury: a retrospective nationwide study in Italy

Purpose

Acute kidney injury (AKI) frequently complicates hospitalization and is associated with in-hospital mortality (IHM). It has been reported a seasonal trend in different clinical conditions. The aim of this study was to evaluate the possible relationship between seasons of the year and IHM in elderly hospitalized patients with AKI.

Methods

We selected all admissions complicated by AKI between 2000 and 2015 recorded in the Italian National Hospital Database. ICD-9-CM code 584.xx identified subjects with age ≥ 65 years and age, sex, comorbidity burden, need of dialysis treatment and IHM were compared in hospitalizations recorded during the four seasons. Moreover, we plotted the AKI observed/expected ratio and percentage of mortality during the study period.

Results

We evaluated 759,720 AKI hospitalizations (mean age 80.5 ± 7.8 years, 52.2% males). Patients hospitalized with AKI during winter months had higher age, prevalence of dialysis-dependent AKI, and number of deceased patients. In whole population IHM was higher in winter and lower in summer, while the AKI observed/expected ratio demonstrated two peaks, one in summer and one in winter. Logistic regression analysis demonstrated that parameters such as age, autumn, winter, comorbidity burden were positively associated with IHM.

Conclusion

We conclude that a seasonality exists in AKI, however, relationship between seasons and AKI could vary depending on the aspects considered. Both autumn and winter months are independent risk factors for IHM in patients with AKI regardless of age, sex and comorbidity burden. On the contrary, summer time reduces the risk of death during hospitalizations with AKI.

Incidence of hospital contacts with acute kidney injury after initiation of second-generation antipsychotics in older adults: a Danish population-based cohort study

Purpose

To investigate the association between acute kidney injury (AKI) and use of second-generation antipsychotics (SGA) in older adults.

Methods

In a population-based cohort study using Danish national registries, new users of SGAs (aged ≥ 65) were identified during 2005–2015. Each SGA user was matched to 10 population controls on age, sex, and the SGA initiation date. The outcome was incident AKI within 90 days after the index date. Cox regression was used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs), adjusting for potential confounders.

Results

In the study, 36,581 new SGA users and 365,810 controls were included. The 90-day incidence rate of AKI was 4.38 and 1.70 per 1000 person-years among SGA users and controls, respectively, corresponding to a crude HR of 2.57 (1.79–3.68). The fully adjusted HR (aHR) was 1.43 (0.89–2.27) for all SGAs. The risk differed among individual drugs with aHRs for olanzapine 3.50 (1.20–10.23), quetiapine 1.62 (0.81–3.26), and risperidone 0.68 (0.28–1.64). In sensitivity analyses, the aHR declined to 1.24 (0.95–1.61) at 1-year follow-up.

Conclusions

Olanzapine use was associated with a significantly increased 90-day AKI risk. For quetiapine, the risk was elevated but not significant, and risperidone had no association. CIs were wide and confounder adjustment largely impacted the estimates. Main limitations included residual confounding and incomplete recording of AKI diagnoses.

Supplementary information

The online version contains supplementary material available at 10.1007/s00228-022-03339-6.

Excess Risk of Major Adverse Cardiovascular and Kidney Events after Acute Kidney Injury following Living Donor Liver Transplantation

Acute kidney injury (AKI) is a well-known risk factor for major adverse kidney events (MAKE) and major adverse cardiovascular events (MACE) in nontransplant settings. However, the association between AKI after liver transplantation (LT) and MACE/MAKE is not established. A retrospective cohort analysis including 512 LT recipients was conducted. The incidence of post-LT AKI was 35.0% (n = 179). In total, 13 patients (2.5%) developed de novo coronary artery disease (CAD), 3 patients (0.6%) diagnosed with heart failure (HF), and 11 patients (2.1%) had stroke. The post-LT AKI group showed a higher incidence of CAD and HF than the no post-LT AKI group (4.5% versus 1.5%, p = 0.042; 1.7% versus 0%, p = 0.018; respectively), while there was no significant difference in the stroke events (2.8% versus 1.8%, p = 0.461). Through Cox regression analysis, history of cardiovascular disease (HR 6.51, 95% CI 2.43–17.46), post-LT AKI (HR 3.06, 95% CI 1.39–6.75), and pre-LT diabetes (HR 2.37, 95% CI 1.09–5.17) were identified as independent predictors of MACE; pre-LT chronic kidney disease (HR 9.54, 95% CI 3.49–26.10), pre-LT diabetes (HR 3.51, 95% CI 1.25–9.86), and post-LT AKI (HR 6.76, 95% CI 2.19–20.91) were risk factors for end-stage renal disease. Post-LT AKI is predictive for the development of MACE and MAKE.

Plants with Therapeutic Potential for Ischemic Acute Kidney Injury: A Systematic Review

Acute kidney injury (AKI) is a complex condition which has an intricate pathology mostly involving hemodynamic, inflammatory, and direct toxic effects at the cellular level with high morbidity and mortality ratios. Renal ischemic reperfusion injury (RIRI) is the main factor responsible for AKI, most often observed in different types of shock, kidney transplantation, sepsis, and postoperative procedures. The RIRI-induced AKI is accompanied by increased reactive oxygen species generation together with the activation of various inflammatory pathways. In this context, plant-derived medicines have shown encouraging nephroprotective properties. Evidence provided in this systemic review leads to the conclusion that plant-derived extracts and compounds exhibit nephroprotective action against renal ischemic reperfusion induced-AKI by increasing endogenous antioxidants and decreasing anti-inflammatory cytokines. However, there is no defined biomarker or target which can be used for treating AKI completely. These plant-derived extracts and compounds are only tested in selected transgenic animal models. To develop the results obtained into a therapeutic entity, one should apply them in proper vertebrate multitransgenic animal models prior to further validation in humans.

Angiotensin1-7 Protects Against Renal Ischemia-Reperfusion Injury via Regulating the Expression of NRF2 and microRNAs in Fisher 344 Rats

Ischemia/reperfusion (I/R) is considered the primary cause of acute kidney injury and is higher among older individuals. While ischemic episodes are hard to predict and prevent, detrimental ischemic effects could be mitigated by exogenous intervention. This study aims to identify the protective role of angiotensin (ANG)1-7 against I/R-induced renal injury in adult vs. aged rats. Adult and aged male Fisher 344 rats were subjected to 40-minute bilateral renal ischemia followed by 28-days reperfusion. ANG1-7 was administered intraperitoneally in ischemic rats for 28 days without or with Mas receptor antagonist A779. I/R increased blood pressure, plasma creatinine, urinary 8-isoprostane, and renal infiltration of pro and anti-inflammatory macrophages and reduced glomerular filtration rate in both adult and aged rats compared to shams. In addition to causing glomerular sclerosis and tubular damage, I/R increased the expression of pathogenic microRNAs (miRNAs): miR-20a-5p, miR-21-5p, miR-24-3p, and miR-194-5p in both the age groups. ANG1-7 treatment of ischemic rats mitigated oxidative stress and renal inflammation, restored renal structure and function, and reduced high blood pressure. Also, ANG1-7 suppressed the expression of pathogenic miRNAs. In addition, ANG1-7 treatment of I/R rats increased the expression of redox-sensitive transcription factor NRF2 and phase II antioxidant enzymes. The beneficial effects of ANG1-7 were sensitive to A779. Collectively, these data suggest that ANG1-7 associated with NRF2 activation could alleviate post-I/R-induced kidney injury and therefore serve as a potential therapeutic compound to protect against biochemical and morphological pathologies of I/R in both adults and aged populations.

Treatment and outcomes among patients ≥85 years hospitalized with community-acquired pneumonia

Our objective was to describe community-acquired pneumonia (CAP) among patients ≥85 years and compare them to patients aged 65-74. This was a retrospective cohort study. The study setting included 638 hospitals in the USA participating in the Premier database from 2010 to 2015. The study participants were 488,382 adults aged ≥65 years hospitalized with CAP. Patients ≥85 years were more likely to be white (79.8% vs 76.2%), female (58.1% vs 48.3%), and admitted with aspiration pneumonia (17.1% vs 7.0%) as compared with those aged 65-75 years. They had higher rates of dementia (30.4% vs 7.8%), but lower rates of diabetes (11.2% vs 17.6%) and chronic obstructive pulmonary disease (25.5% vs 54.7%). While Staphylococcus aureus (33.4%) was the most common pathogen across all age groups, patients aged ≥85 were more likely to have Escherichia coli pneumonia (16.1% vs 10.7%) compared with those aged 65-74. In adjusted models, patients aged ≥85 had greater in-hospital mortality (OR 1.14, 95% CI 1.11 to 1.18), but were less likely to be admitted to the intensive care unit (OR 0.54, 95% CI 0.53 to 0.55) and receive mechanical ventilation (OR 0.47, 95% CI 0.46 to 0.48). They also had lower rates of acute kidney injury (OR 0.95, 95% CI 0.91 to 1.00) and Clostridium difficile infection (OR 0.91, 95% CI 0.85 to 0.99), shorter lengths of stay (mean multiplier 0.93, 95% CI 0.92 to 0.93) and lower cost (mean multiplier 0.81, 95% CI 0.80 to 0.81), and were more likely to be discharged to a skilled nursing facility (OR 2.19, 95% CI 2.15 to 2.24) or hospice (OR 2.19, 95% CI 2.11 to 2.27). In conclusion, patients aged ≥85 have different comorbidities and etiologies of CAP, receive less intense treatment, and have greater mortality than patients between 65 and 75 years.

Impact of providing patient information leaflets prior to hospital discharge to patients with acute kidney injury: a quality improvement project

Acute kidney injury (AKI) is a common health issue. It is a sudden episode of kidney failure that is almost entirely associated with episodes of acute illness. AKI is common with as many as 20% of patients arriving at hospital having an AKI, with up to 15% of patients developing AKI in a postoperative period. Patients who have an episode of AKI are more likely to have a further episode of AKI and require readmission to hospital. This project aimed to provide patients with AKI education for self-care and management, with the hope of reducing AKI readmissions.

Using quality improvement methodology, the AKI patient discharge and readmission pathway was reviewed, and information about AKI was given to patients. This was in the form of verbal information and a patient information leaflet. This information was provided on discharge from acute care.

Baseline data were collected that showed more than 80% of patients reported that they were not given information about AKI prior to their discharge from hospital. Due to higher readmission rates, the focus of this improvement project was on acute medical wards. Following implementation, there was a sustained reduction in AKI patient readmission rates. This reduction led to a significant reduction of inpatient bed days and a shorter length of stay for those patients who were readmitted. Quality improvement methods have facilitated a successful reduction in acute AKI readmission to hospital.

Haemodynamic frailty - A risk factor for acute kidney injury in the elderly

Clinical frailty in the elderly is defined by a composite measure of functional psychomotor decline. Herein, we develop the concept of haemodynamic frailty (HDF), a state of increased predisposition to disease prevalent in the elderly and characterised by impairment of the network of compensatory responses governing the defence of circulatory volume and adaptive haemodynamic function. We review the factors predisposing the elderly to HDF, with a focus on the impaired capacity to sustain total body water balance. As a component of HDF, dehydration generates vulnerability to diseases caused by tissue hypoperfusion, including acute kidney injury. We provide a detailed mechanistic explanation of how dehydration and depletion of the intravascular volume impacts on renal blood flow to become an important element of the heightened risk of acute kidney injury (AKI) in the elderly. We bring these mechanistic considerations into the clinical context with reference to examples of how pre-renal (haemodynamic) and intrinsic (involving renal parenchymal damage) AKI risk is elevated in the setting of dehydration. Finally, we present HDF as a state of opportunity to prevent disease, for which diagnostic and interventional standards need to be refined. Further prospective studies are warranted to help clarify the clinical utility of assessing and managing HDF with regard to the mitigation of AKI risk in the elderly.

Utility of suPAR and NGAL for AKI Risk Stratification and Early Optimization of Renal Risk Medications among Older Patients in the Emergency Department

Diagnosis of acute kidney injury (AKI) based on plasma creatinine often lags behind actual changes in renal function. Here, we investigated early detection of AKI using the plasma soluble urokinase plasminogen activator receptor (suPAR) and neutrophil gelatinase-sssociated lipocalin (NGAL) and observed the impact of early detection on prescribing recommendations for renally-eliminated medications. This study is a secondary analysis of data from the DISABLMENT cohort on acutely admitted older (≥65 years) medical patients (n = 339). Presence of AKI according to kidney disease: improving global outcomes (KDIGO) criteria was identified from inclusion to 48 h after inclusion. Discriminatory power of suPAR and NGAL was determined by receiver-operating characteristic (ROC). Selected medications that are contraindicated in AKI were identified in Renbase®. A total of 33 (9.7%) patients developed AKI. Discriminatory power for suPAR and NGAL was 0.69 and 0.78, respectively, at a cutoff of 4.26 ng/mL and 139.5 ng/mL, respectively. The interaction of suPAR and NGAL yielded a discriminatory power of 0.80, which was significantly higher than for suPAR alone (p = 0.0059). Among patients with AKI, 22 (60.6%) used at least one medication that should be avoided in AKI. Overall, suPAR and NGAL levels were independently associated with incident AKI and their combination yielded excellent discriminatory power for risk determination of AKI.

Exploration of the Relationship Among Key Risk Factors of Acute Kidney Injury for Elderly Patients Considering Covid-19

Background: Previous systematic reviews and meta-analyses supported the relationship between frailty and risk of acute kidney injury (AKI) in elderly patients. However, few studies evaluated proactive management to wear down AKI risk in such frail populations.

Purpose: To understand how AKI risk factors might influence each other and to identify the source factors for clinical decision aids.

Methods: This study uses the decision-making trial and evaluation laboratory (DEMATEL) method to establish influential network-relationship diagrams (INRDs) to form the AKI risk assessment model for the elderly.

Results: Based on the DEMATEL approach, the results of INRD identified the six key risk factors: comorbidity, malignancy, diabetes, creatinine, estimated glomerular filtration rate, and nutritional assessment. (The statistical significance confidence is 98.423%, which is higher than 95%; the gap error is 1.577%, which is lower than 5%). After considering COVID-19 as an additional risk factor in comorbidity, the INRD revealed a similar influential relationship among the essential aspects.

Conclusion: While evaluating the geriatric population, physicians need to pay attention to patients' comorbidities and nutritional assessment; also, they should note patients' creatinine values and glomerular filtration rate. Physicians could establish a preliminary observation index and then design a series of preventive guidelines to reduce the incidence of AKI risk for the elderly.

Risk Factors for Acute Kidney Injury in COVID-19 Patients: A Systematic Review

BACKGROUND: Acute kidney injury (AKI) in coronavirus disease-19 (COVID-19) has high incidence and mortality. Risk factors for AKI in COVID-19 patients are not well explored. This systematic review provides a combination of available evidence regarding risk factors of AKI in COVID-19 patients. METHODS: A systematic research was performed in Medline, Cochrane Central Register of Controlled Trials, and ScienceDirect journal databases from 2019 to August 2020. The study selection process was plotted using a Preferred Reporting Items for Systematic Review and Meta-Analyses flow diagram. RESULTS: Out of 553 studies found, four full-text studies met the inclusion criteria and were included in qualitative analysis. There are 2205 COVID-19 patients with AKI (36.44%) from 6051 COVID-19 patients. Age was a risk factors for AKI in two studies (odds ratio [OR] 1.03 [p < 0.001], OR 1.03 [p < 0.007]). Critical condition of patient is risk factors for AKI (OR 8.155 [p = 0.006]). Hirsch et al. stated that diabetes mellitus (OR 1.74 [p < 0.001]), cardiovascular disease (OR 1.48 [p < 0.001]), and hypertension (OR 1.25 [p = 0.02]) are also risk factors. Laboratory results such as elevated procalcitonin (PCT) and estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2 showed positive association to AKI in COVID-19 patients (OR 4.822 [p = 0.037]; OR 13.451 [p = 0.016]). A higher sequential organ failure assessment (SOFA) score at admission is one of the risk factors (OR 1.498 [p = 0.027]). CONCLUSION: Demographics, clinical classification of COVID-19, comorbidities, SOFA score, PCT, and eGFR can help clinicians predict AKI in COVID-19 patients.

The Effect of Coronary Angiography Timing on Cardiac Surgery Associated Acute Kidney Injury Incidence and Prognosis

Introduction: Acute kidney injury has been identified as a common complication of cardiac surgery. To date, the effect of the time interval from coronary angiography to cardiac surgery on postoperative acute kidney injury is still controversial. The aim of this study was to investigate the relationship between the timing of coronary angiography and cardiac surgery associated acute kidney injury.

Methods: Eight hundred thirteen patients who underwent coronary angiography and cardiac surgery successively from January 2017 to December 2018 were included in this retrospective cohort study. We applied multivariate logistic regression, propensity score analysis, and subgroup analysis to evaluate the association between the time interval and postoperative acute kidney injury incidence and prognosis. Meta-analysis was conducted to verify the results.

Results: The overall incidence of the cardiac surgery associated acute kidney injury was 28.8%. Age (OR = 1.046, 95%CI: 1.017–1.075), cardiopulmonary bypass (OR = 3.439, 95%CI: 1.316–8.986) and diabetes (OR = 2.522, 95%CI: 1.439–4.417) were found to be independent risk factors of postoperative acute kidney injury in multivariate logistic regression and propensity score analysis. Undergoing cardiac surgery within 7 days after coronary angiography was not associated with increased incidence of postoperative acute kidney injury or worse prognosis. Meta-analysis obtained consistent results.

Conclusions: The time interval shorter than 7 days had no influence on cardiac surgery associated acute kidney injury incidence and prognosis. The decision of delaying the surgery should be made after comprehensive evaluation of the patient.

Influence of aging on deterioration of patients with COVID-19

Aging is an important factor affecting the deterioration of patients with coronavirus disease 2019 (COVID-19). The aging and degeneration of various tissues and organs in the elderly lead to impaired organ function. Underlying conditions such as chronic lung disease, cardiovascular disease, and diabetes in aged patients are associated with higher mortality. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) primarily interacts with the cell surface receptor angiotensin-converting enzyme (ACE) 2 and other accessory proteins such as 78 kDa glucose-regulated protein 78 (GRP78) and CD147. Thus, altered receptor signals in aging and chronic disease play a role in SARS-CoV-2 infection, and are associated with a higher risk of deterioration in different organs. In this review, after a brief introduction to the link between aging and receptors for SARS-CoV-2, we focus on the risk of deterioration in different organs of COVID-19 patients considering aging as the main factor. We further discuss the structural and/or physiological changes in the immune system and organs (lung, heart, kidney, vessels, nerve system), as well as those associated with diabetes, in aging patients, and speculate on the most likely mechanisms underlying the deterioration of COVID-19 patients.

Single-Cell Profiling of AKI in a Murine Model Reveals Novel Transcriptional Signatures, Profibrotic Phenotype, and Epithelial-to-Stromal Crosstalk

BACKGROUND

Current management of AKI, a potentially fatal disorder that can also initiate or exacerbate CKD, is merely supportive. Therefore, deeper understanding of the molecular pathways perturbed in AKI is needed to identify targets with potential to lead to improved treatment.

METHODS

We performed single-cell RNA sequencing (scRNA-seq) with the clinically relevant unilateral ischemia-reperfusion murine model of AKI at days 1, 2, 4, 7, 11, and 14 after AKI onset. Using real-time quantitative PCR, immunofluorescence, Western blotting, and both chromogenic and single-molecule in situ hybridizations, we validated AKI signatures in multiple experiments.

RESULTS

Our findings show the time course of changing gene expression patterns for multiple AKI stages and all renal cell types. We observed elevated expression of crucial injury response factors-including kidney injury molecule-1 (Kim1), lipocalin 2 (Lcn2), and keratin 8 (Krt8)-and of several novel genes (Ahnak, Sh3bgrl3, and Col18a1) not previously examined in kidney pathologies. AKI induced proximal tubule dedifferentiation, with a pronounced nephrogenic signature represented by Sox4 and Cd24a. Moreover, AKI caused the formation of "mixed-identity cells" (expressing markers of different renal cell types) that are normally seen only during early kidney development. The injured tubules acquired a proinflammatory and profibrotic phenotype; moreover, AKI dramatically modified ligand-receptor crosstalk, with potential pathologic epithelial-to-stromal interactions. Advancing age in AKI onset was associated with maladaptive response and kidney fibrosis.

CONCLUSIONS

The scRNA-seq, comprehensive, cell-specific profiles provide a valuable resource for examining molecular pathways that are perturbed in AKI. The results fully define AKI-associated dedifferentiation programs, potential pathologic ligand-receptor crosstalk, novel genes, and the improved injury response in younger mice, and highlight potential targets of kidney injury.

Comparison of Outcomes of Transcatheter Mitral Valve Repair (MitraClip) in Patients <80 Years Versus ≥80 Years

The influence of age on outcomes of patients selected for transcatheter mitral valve repair (TMVR) remains largely unknown in the United States. This study sought to assess the outcomes of TMVR in highly aged patients (≥80 years). We queried the National Readmission Database from January 2014 to December 2016 for elective TMVR hospitalizations. Propensity-score matching was used to compare in-hospital and 30-day outcomes between highly aged patients and those less than 80 years. Of 6,025 (weighted national estimate) hospitalizations for TMVR, total of 3,368 included highly aged patients (mean age 85.3) and 2,657 included patients less than 80 years (mean age 69). In the Propensity-score matched cohort (age≥ 80, n = 2,185; age <80, n = 2,197), highly aged patients had similar rates of in-hospital mortality (2.2% vs 1.6%; p = 0.22), ischemic stroke (0.5% vs 0.5%; p = 0.83), cardiac tamponade (0.2% vs 0.4%; p = 0.58), cardiogenic shock (1.2% vs 1.7%; p = 0.25), and acute myocardial infarction (0.6% vs 0.4%; p = 0.30), but higher rates of discharge to skilled nursing facility(9.7% vs 4.5%; p <0.001), all-cause 30-day readmissions (14.2% vs 10.5%; p <0.001), and heart failure-related 30-day readmissions (4.7% vs 3.0%; p = 0.006), compared with those less than 80 years. TMVR therapy is safe and is associated with low rates of in-hospital adverse events but higher rate of 30-day readmissions in highly aged patients compared with patients less than 80 years. Evidence-based interventions proven to be effective in reducing the burden of heart failure readmissions should be utilized in these patients to further improve outcomes.

Molecular Mechanisms of AKI in the Elderly: From Animal Models to Therapeutic Intervention

Acute kidney injury (AKI), a critical syndrome characterized by a sudden reduction of renal function, is a common disorder among elderly patients particularly in Intensive Care Unit (ICU). AKI is closely associated with both short- and long-term mortality and length of hospital stay and is considered a predictor of chronic kidney disease (CKD). Specific hemodynamic, metabolic, and molecular changes lead to increased susceptibility to injury in the aged kidney; therefore, certain causes of AKI such as the prerenal reduction in renal perfusion or vascular obstructive conditions are more common in the elderly; moreover, AKI is often multifactorial and iatrogenic. Older patients present several comorbidities (diabetes, hypertension, heart failure) and are exposed to multiple medical interventions such as the use of nephrotoxic contrasts media and medications, which can also trigger AKI. Considering the emerging relevance of this condition, prevention and treatment of AKI in the elderly should be crucial in the internist and emergency setting. This review article summarizes the incidence, the risk factors, the pathophysiology, the molecular mechanisms and the strategies of prevention and treatment of AKI in elderly patients.

Predicting Acute Kidney Injury: A Machine Learning Approach Using Electronic Health Records

Acute kidney injury (AKI) is a common complication in hospitalized patients and can result in increased hospital stay, health-related costs, mortality and morbidity. A number of recent studies have shown that AKI is predictable and avoidable if early risk factors can be identified by analyzing Electronic Health Records (EHRs). In this study, we employ machine learning techniques to identify older patients who have a risk of readmission with AKI to the hospital or emergency department within 90 days after discharge. One million patients’ records are included in this study who visited the hospital or emergency department in Ontario between 2014 and 2016. The predictor variables include patient demographics, comorbid conditions, medications and diagnosis codes. We developed 31 prediction models based on different combinations of two sampling techniques, three ensemble methods, and eight classifiers. These models were evaluated through 10-fold cross-validation and compared based on the AUROC metric. The performances of these models were consistent, and the AUROC ranged between 0.61 and 0.88 for predicting AKI among 31 prediction models. In general, the performances of ensemble-based methods were higher than the cost-sensitive logistic regression. We also validated features that are most relevant in predicting AKI with a healthcare expert to improve the performance and reliability of the models. This study predicts the risk of AKI for a patient after being discharged, which provides healthcare providers enough time to intervene before the onset of AKI.

Acute kidney injury following on-pump or off-pump coronary artery bypass grafting in elderly patients: a retrospective propensity score matching analysis

Objectives

This single-centre, retrospective propensity score matching (PSM) study designed to study the impact of cardiopulmonary bypass (CPB) on postoperative acute kidney injury (AKI) and the relationship between AKI and long-term outcomes in elderly patients undergoing coronary artery bypass grafting (CABG).

Methods

After PSM, 466 pairs of patients (A group, on-pump; B group, off-pump) who were aged≥70 years undergoing first isolated CABG surgery from January 2012 to December 2016 entered the study. AKI was defined and classified according to the Acute Kidney Injury Network (AKIN) criteria. The incidence and severity of in-hospital AKI were compared. The impacts of AKI on the long-term outcomes including new onset of dialysis and mortality were analyzed.

Results

The two PSM groups had similar baseline and procedure except whether the CPB was used or not. In hospital and 30-day mortality was of no difference(χ2 = 0.051, p = 0.821). AKI of any severity occurred in 40.3% of all patients, with stage 1 accounting for most cases. No difference regarding the incidence and severity of AKI could be found: AKIN stage 1: 139 (29.8%) vs 131 (28.1%); AKIN stage 2: 40 (8.6%) vs 35 (7.5%); AKIN stage 3: 18 (3.9%) vs 13 (2.8%), (u = 0.543, p = 0.532). No difference was observed in the in-hospital new onset of dialysis (χ2 = 0.312, P = 0.576). The use of CPB was not found to influence long-term new onset of dialysis (χ2 = 0.14, p = 0.708) and mortality (χ2 = 0.099, p = 0.753). Comparing with non-AKI patients, AKI patients were associated with an increased rates of new onset of dialysis (χ2 = 8.153, p = 0.004) and mortality (χ2 = 6.277, p = 0.012) during the follow-up. Multivariable logistic regression manifested that the HR for long-term new onset of dialysis and mortality in AKI patients vs. non-AKI patients was 1.83 and 1.31 respectively (95%CI 1.12–2.86, p = 0.007; 95%CI 1.17–2.58, p = 0.015). The HR for long-term new onset of dialysis and mortality in on-pump group vs. off-pump group was 1.07 and 1.11 respectively (95%CI 1.03–1.23, p = 0.661; 95%CI 1.09–1.64, p = 0.702).

Conclusions

For elderly CABG patients, AKI was common, but deterioration of dialysis was a seldom incidence. Comparing with on-pump, off-pump did not decrease the rates or severity of AKI, long-term new onset of dialysis or mortality. AKI was associated with an increased long-term new onset of dialysis and decreased long-term survival.

Ten-eleven translocation methyl-cytosine dioxygenase 2 deficiency exacerbates renal ischemia-reperfusion injury

BACKGROUND

Ten-eleven translocation (Tet) methyl-cytosine dioxygenases (including Tet1/2/3)-mediated 5mC oxidation and DNA demethylation play important roles in embryonic development and adult tissue homeostasis. The expression of Tet2 and Tet3 genes are relatively abundant in the adult murine kidneys while Tet1 gene is expressed at a low level. Although Tet3 has been shown to suppress kidney fibrosis, the role of Tet2 in kidney physiology as well as renal ischemia-reperfusion (IR) injury is still largely unknown.

RESULTS

Tet2^-/- mice displayed normal kidney morphology and renal function as WT mice while the expression of genes associated with tight junction and adherens junction was impaired. At 24 h post-renal IR, Tet2^-/- mice showed higher SCr and BUN levels, more severe tubular damage, and elevated expression of Kim1 and Ngal genes in the kidney in comparison with WT mice. Moreover, the transcriptomic analysis revealed augmented inflammatory response in the kidneys of Tet2^-/- mice.

CONCLUSIONS

Tet2 is dispensable for kidney development and function at baseline condition while protects against renal IR injury possibly through repressing inflammatory response. Our findings suggest that Tet2 may be a potential target for the intervention of IR-induced acute kidney injury (AKI).

Impact of Kidney Donor Profile Index Scores on Post-Transplant Clinical Outcomes Between Elderly and Young Recipients, A Multicenter Cohort Study

We investigated if clinical outcomes after kidney transplantation (KT) from deceased donors (DDs) with high Kidney Donor Profile Index (KDPI) can be different according to the age of KT recipients (KTRs). Six-hundred fifty-seven KTRs from 526 DDs were included from four transplant centers. We divided KTRs into elderly-KTR and young-KTR groups based on age 60 and each group was subdivided into high- or low-KDPI subgroup based on KDPI score of 65%. We compared short-term and long-term clinical outcomes among those four subgroups (low KDPI-young KTR, low KDPI-elderly-KTR, high KDPI-young-KTR, high KDPI-elderly-KTR). In short-term outcomes including acute rejection, BK virus and CMV infection, there was no significant difference among the four subgroups. In the long-term outcomes, the development of cardiovascular disease was higher in the high KDPI-elderly-KTR group than the other groups. In comparison of allograft survival rate, the high KDPI-young KTR subgroup showed highest risk for allograft failure and there was significant interaction between high-KDPI donors and young-KTR on allograft survival rate (P = 0.002). However, there was no significant difference in comparison of the patient survival rate. In conclusion, clinical impact of high-KDPI in DDs on post-transplant allograft survival may be less significant in elderly-KTR than in young-KTR.

Impact of acute kidney injury in elderly versus young deceased donors on post-transplant outcomes: A multicenter cohort study

We investigated the impact of acute kidney injury (AKI) in elderly deceased-donors (DDs) vs. AKI in young DDs on post-transplant clinical outcomes. A total of 709 kidney transplant recipients (KTRs) from 602 DDs at four transplant centers were enrolled. KTRs were divided into young-DDKT and elderly-DDKT groups according to the age of DD of 60 years. Both groups were subdivided into non-AKI-KT and AKI-KT subgroups according to AKI in DDs. We investigated short-term and long-term clinical outcomes of non-AKI-DDKT and AKI-DDKT subgroups within young-DDKT and elderly-DDKT groups. The incidence of DGF in the AKI-DDKT subgroup was higher and the allograft function within 12 months after KT in the AKI-DDKT subgroup was lower than those in the non-AKI-DDKT subgroup in both young-DDKT and elderly-DDKT groups. Death-censored allograft survival rate was significantly lower in the AKI-elderly-DDKT subgroup than that in the non-AKI-elderly-DDKT subgroup, but it did not differ between AKI-young-DDKT and non-AKI-young-DDKT subgroup. In multivariable analysis, AKI-elderly-DDKT was an independent risk factor for allograft failure (hazard ratio: 2.648, 95% CI: 1.170-5.994, p = 0.019) and a significant interaction between AKI and old age in DDs on allograft failure was observed (p = 0.001). AKI in elderly DDs, but not in young DDs, can significantly affect long-term allograft outcomes of KTRs.

Predictive role of estimated glomerular filtration rate prior to surgery in postsurgical acute kidney injury among very elderly patients: a retrospective cohort study

Background: Acute kidney injury (AKI) is a common complication after surgery. Because of unpredictable and variable age-dependent physical decline, the incidence, risk factor of postsurgical AKI and the predictive power of estimated glomerular filtration rate prior to surgery (eGFRpreSurg) has not been fully elucidated in very elderly patients.

Methods: All discharged patients aged ≥80 years without chronic kidney disease who underwent surgery prior to intensive care unit (ICU) admission from 2017 through 2018 were included. Clinical, biological and surgical data were recorded. Mean of outpatient creatinine values from the year prior to ICU admission was used as the baseline value to determine the occurrence of AKI. Postoperative AKI was diagnosed according to Kidney Disease Improving Global Outcomes criteria.

Results: Among 243 very elderly postoperative patients admitted during the study period, 48 had AKI during their ICU stay. The occurrence of postsurgical AKI was associated with longer ventilation times (p < .001) and higher mortality (p < .001). The eGFRpreSurg, which is calculated based on the Modification of Diet in Renal Disease study equation, was a risk factor for postoperative AKI (OR = 2.662, p = .010). The incidence of postoperative AKI was significantly higher among patients with lower eGFRpreSurg than among those with an eGFRpreSurg ≥ 70 mL/min/1.73 m² (p = .003).

Conclusion: Postsurgical AKI in very elderly patients has a high incidence and is a risk factor for mortality. Our study confirmed that eGFRpreSurg could be used as an index for AKI risk stratification.

Brain-kidney interaction: Renal dysfunction following ischemic stroke

Stroke is a leading cause of mortality and morbidity, with long-term debilitating effects. Accumulating evidence from experimental studies as well as observational studies in patients suggests a cross talk between the brain and kidney after stroke. Stroke may lead to kidney dysfunction which can adversely impact patient outcome. In this review article, we discuss the epidemiology and mechanisms of brain–kidney interaction following ischemic stroke. Specifically, we discuss the role of the central autonomic network, autoregulation, inflammatory and immune responses, the role of extracellular vesicles and their cargo microRNA, in mediating brain–kidney interaction following stroke. Understanding the bidirectional nature of interaction between the brain and kidney after cerebral injury would have clinical implications for the treatment of stroke and overall patient outcome.

Advances on Cell Autophagy and Its Potential Regulatory Factors in Renal Ischemia-Reperfusion Injury

Ischemia-reperfusion injury is a major reason for acute kidney injury and various kidney diseases. Autophagy plays an important role during renal ischemia-reperfusion injury (RIRI), but it remains controversial whether autophagy contributes to cell survival or ischemia-reperfusion-induced cell death. In the review, we summarized the function of autophagy in the progression of acute ischemic kidney injury, as well as its related molecular mechanisms. While analyzing the opposite roles of autophagy in RIRI, it was concluded that the protective or detrimental function of autophagy was depending on the timing and amount of the activation of cell autophagy. We also summarized the regulatory agents, including active compounds, proteins, or microRNAs (miRNAs), which regulated the cell autophagy during renal acute ischemic kidney injury process. This explained why the opposite conclusion occurred when cell autophagy was studied in the RIRI models from different researchers. Therefore, the article provided a hypothesis to control cell autophagy at the appropriate timing and intensity so as to alleviate renal injury and sustain cell survival of the renal cell.

Evaluation of Acute Kidney Injury Associated With Anticancer Drugs Used in Gastric Cancer in the Japanese Adverse Drug Event Report Database

Background: Development of acute kidney injury (AKI) depends on the severity of renal dysfunction, clinical setting, comorbid factors, and geographical location. Gastric cancer is one of the deadliest malignancies worldwide, and its incidence is significantly high in Japan. Objective: We analyzed the rank-order of the association of anticancer agents for gastric cancer with AKI using a spontaneous reporting system database, the Japanese Adverse Drug Event Report database. Methods: We performed a retrospective pharmacovigilance disproportionality analysis using the adverse event reports submitted to the Pharmaceuticals and Medical Devices Agency between April 2004 and March 2017. Results: Anticancer drug-related AKI was common in patients in their 60s and 70s (39.2% and 43.2%, respectively). AKI occurred most frequently within 1 month after anticancer drug administration. The signals of AKI were reported after treatment with S-1 (tegafur/gimeracil/oteracil), cisplatin (CDDP), and capecitabine, with significant adjusted reporting odds ratios (95% CI) of 1.50 (1.09-2.07), 3.43 (2.48-4.74), and 1.82 (1.15-2.90), respectively. CDDP-induced AKI was more likely to occur in patients who were male, hypertension, or diabetes mellitus. Conclusion and Relevance: This study showed that most AKI cases were related to S-1 and/or CDDP adjuvant chemotherapy for gastric cancer treatment. The data also clarified that AKIs occurred within 1 month and that their clinical outcomes were more severe than previous reports of drug-induced AKI in general medicine. Our study provides useful information to minimize the risks of administration to patients at high risk for S-1 and/or CDDP containing chemotherapy-induced AKI.

Acute kidney injury and the risk of mortality in patients with methanol intoxication

Background

Methanol poisoning is a serious public health issue in developing countries, but few data are available in the literature on acute kidney injury (AKI) after methanol intoxication.

Methods

This study examined the clinical features, spectrum and outcomes of AKI in patients with methanol intoxication and evaluated the predictors of mortality after methanol intoxication. A total of 50 patients with methanol intoxication were seen at Chang Gung Memorial Hospital between 2000 and 2013. Patients were grouped according to the status of renal damage as AKI (n = 33) or non-AKI (n = 19). Demographic, clinical, laboratory, and mortality data were obtained for analysis.

Results

Most patients were middle-aged (47.8 ± 14.9 years), predominantly male (74.0%), and habitual alcohol consumers (70.0%). Most incidents were oral exposures (96.0%) and unintentional (66.0%). Two (4.0%) patients attempted suicide by intravenous injection of methanol. Five (10.0%) patients suffered methanol intoxication after ingestion of methomyl pesticide that contained methanol as a solvent. Compared to non-AKI patients, the AKI patients were older (50.9 ± 13.7 versus 41.6 ± 15.6 years, P = 0.034), predominantly male (90.9% versus 42.8%, P = 0.000), more habitual alcohol users (84.8% versus 41.2%, P = 0.001) and had more unintentional exposures (82.8% versus 35.3%, P = 0.001). Furthermore, there was a higher incidence of respiratory failure (63.6% versus 29.4%, P = 0.022) in the AKI group than in the non-AKI group, respectively. The laboratory studies revealed that the AKI patients suffered from more severe metabolic acidosis than the non-AKI patients. By the end of this study, 13 (39.5%) AKI patients and 1 (5.9%) non-AKI patient had died. The overall in-hospital hospital mortality rate was 28%. In a multivariate binary logistic regression model, it was demonstrated that AKI (odds ratio 19.670, confidence interval 1.026–377.008, P = 0.048) and Glasgow coma scale score (odds ratio 1.370, confidence interval 1.079–1.739, P = 0.010) were significant factors associated with mortality. The Kaplan-Meier analysis disclosed that AKI patients suffered lower cumulative survival than non-AKI patients (log-rank test, chi-square = 5.115, P = 0.024).

Conclusions

AKI was common (66.0%) after methanol intoxication and was predictive of in-hospital hospital mortality. The development of AKI was associated with a 19.670-fold higher risk of in-hospital mortality.

The role of PAK1 in the sensitivity of kidney epithelial cells to ischemia-like conditions

Kidney ischemia, characterized by insufficient supply of oxygen and nutrients to renal epithelial cells, is the main cause of acute kidney injury and an important contributor to mortality world-wide. Earlier research implicated a G-protein coupled receptor (NK1R) in the death of kidney epithelial cells in ischemia-like conditions. P21-associated kinase 1 (PAK1) is involved in signalling by several G-proteins. We explored the consequences of PAK1 inhibition for cell survival under the conditions of reduced glucose and oxygen. Inhibition of PAK1 by RNA interference, expression of a dominant-negative mutant or treatment with small molecule inhibitors greatly reduced the death of cultured kidney epithelial cells. Similar protection was achieved by treating the cells with inhibitors of MEK1, in agreement with the prior reports on PAK1-MEK1 connection. Concomitant inhibition of NK1R and PAK1 offered no better protection than inhibition of NK1R alone, consistent with the two proteins being members of the same pathway. Furthermore, NK1R, PAK and MEK inhibitors reduced the induction of TRAIL in ischemia-like conditions. Considering the emerging role of TRAIL in ischemia-mediated cell death, this phenomenon may contribute to the protective effects of these small molecules. Our findings support further exploration of PAK and MEK inhibitors as possible agents to avert ischemic kidney injury.