Acute Kidney Injury and Subsequent Frailty Status in Survivors of Critical Illness: A Secondary Analysis

The Road to Precision Medicine for Acute Kidney Injury

OBJECTIVES

Acute kidney injury (AKI) is a common form of organ dysfunction in the ICU. AKI is associated with adverse short- and long-term outcomes, including high mortality rates, which have not measurably improved over the past decade. This review summarizes the available literature examining the evidence of the need for precision medicine in AKI in critical illness, highlights the current evidence for heterogeneity in the field of AKI, discusses the progress made in advancing precision in AKI, and provides a roadmap for studying precision-guided care in AKI.

DATA SOURCES

Medical literature regarding topics relevant to precision medicine in AKI, including AKI definitions, epidemiology, and outcomes, novel AKI biomarkers, studies of electronic health records (EHRs), clinical trial design, and observational studies of kidney biopsies in patients with AKI.

STUDY SELECTION

English language observational studies, randomized clinical trials, reviews, professional society recommendations, and guidelines on areas related to precision medicine in AKI.

DATA EXTRACTION

Relevant study results, statements, and guidelines were qualitatively assessed and narratively synthesized.

DATA SYNTHESIS

We synthesized relevant study results, professional society recommendations, and guidelines in this discussion.

CONCLUSIONS

AKI is a syndrome that encompasses a wide range of underlying pathologies, and this heterogeneity has hindered the development of novel therapeutics for AKI. Wide-ranging efforts to improve precision in AKI have included the validation of novel biomarkers of AKI, leveraging EHRs for disease classification, and phenotyping of tubular secretory clearance. Ongoing efforts such as the Kidney Precision Medicine Project, identifying subphenotypes in AKI, and optimizing clinical trials and endpoints all have great promise in advancing precision medicine in AKI.

Outcomes after acute kidney injury and critical illness

PURPOSE OF REVIEW

Acute kidney injury (AKI) in critical illness is common, and survivors are faced with a host of adverse outcomes. In this article, we review the current landscape of outcomes and care in survivors of AKI and critical illness.

RECENT FINDINGS

Follow-up care of survivors of AKI and critical illness is prudent to monitor for and mitigate the risk of adverse outcomes. Observational data have suggested improvement in outcomes with nephrology-based follow-up care, and recent interventional studies demonstrate similar findings. However, current post-AKI care is suboptimal with various challenges, such as breakdowns in the transition of care during hospital episodes and into the community, barriers for patients in follow-up, and lack of identification of high-risk patients for nephrology-based follow-up. Tools predictive of renal nonrecovery and long-term outcomes may help to identify high-risk patients who may benefit the most from nephrology-based care post-AKI.

SUMMARY

Follow-up care of survivors of AKI and critical illness may improve outcomes and there is a need to prioritize transitions of care into the community. Further research is needed to elucidate the best ways to risk-stratify and manage post-AKI survivors to improve outcomes.

Quality of life after acute kidney injury

PURPOSE OF REVIEW

Deciphering the effect of acute kidney injury (AKI) during critical illness on long-term quality of life versus the impact of conditions that brought on critical illness is difficult.

RECENT FINDINGS

Reports on patient-centred outcomes such as health-related quality of life (HRQOL) have provided insight into the long-lasting impact of critical illness complicated by AKI. However, these data stem from observational studies and randomized controlled trials, which have been heterogeneous in their patient population, timing, instruments used for assessment and reporting. Recent studies have corroborated these findings including lack of effect of renal replacement therapy compared to severe AKI on outcomes and worse physical compared to cognitive dysfunction.

SUMMARY

In adults, more deficits in physical than mental health domains are found in survivors of AKI in critical care, whereas memory deficits and learning impairments have been noted in children. Further study is needed to understand and develop interventions that preserve or enhance the quality of life for individual patients who survive AKI following critical illness, across all ages.

The impact of early versus late initiation of renal replacement therapy in critically ill patients with acute kidney injury on mortality and clinical outcomes: a meta-analysis

Background

Renal replacement therapy (RRT) is essential in the presence of life-threatening complications associated with acute kidney injury (AKI). In the absence of urgent indications, the optimal timing for RRT initiation is still under debate. This meta-analysis aims to compare the benefits between early and late RRT initiation strategies in critically ill patients with AKI.

Methods

Studies were obtained from three databases [Medical Literature Analysis and Retrieval System Online (MEDLINE), Cochrane Central Register of Controlled Trials (CENTRAL) and Scopus], searched from inception to May 2021. The selected primary outcome was 28-day mortality. Secondary outcomes included overall mortality, recovery of renal function (RRF) and RRT-associated adverse events. A random-effects model was used for summary measures. Heterogeneity was assessed through Cochrane I² test statistics. Potential sources of heterogeneity for the primary outcome were sought using sensitivity analyses. Further subgroup analyses were conducted based on RRT modality and study population.

Results

A total of 13 randomized controlled trials including 5193 participants were analysed. No significant differences were found between early and late RRT initiation regarding 28-day mortality [risk ratio (RR) 1.00; 95% confidence interval (CI) 0.89–1.12, I² = 30%], overall mortality (RR 1.00; 95% CI 0.90–1.12, I² = 42%) and RRF (RR 1.02; 95% CI 0.92–1.13, I² = 53%). However, early RRT initiation was associated with a significantly higher incidence of hypotensive (RR 1.34; 95% CI 1.17–1.53, I² = 6%) and infectious events (RR 1.83; 95% CI 1.11–3.02, I² = 0%).

Conclusions

Early RRT initiation does not improve the 28-day and overall mortality, nor the likelihood of RRF, and increases the risk for RRT-associated adverse events, namely hypotension and infection.

Overview of Diagnostic Criteria and Epidemiology of Acute Kidney Injury and Acute Kidney Disease in the Critically Ill Patient

Since the description ischuria renalis by William Heberden (1), AKI has remained a prominent complication of critical illness. Beyond KRT, treatment has been limited by the capacity to phenotype this condition. Here, we chronicle the evolution of attempts to classify AKI, including the adoption of consensus definitions, the expansion of diagnosis and prognosis with novel biomarkers, and emerging tools such as artificial intelligence (AI).

Acute kidney injury contributes to worse physical and quality of life outcomes in survivors of critical illness

Objectives

Survivors of critical illness and acute kidney injury (AKI) are at risk of increased morbidity. The purpose of this study was to compare physical, emotional, and cognitive health in survivors of critical illness with and without AKI.

Methods

Retrospective cohort study of adult (≥ 18 years old) survivors of critical illness due to sepsis and/or acute respiratory failure who attended follow-up in a specialized ICU Recovery Clinic. Outcomes were evaluated during 3-month visit and comprised validated tests for evaluation of physical function, muscle strength, cognitive and emotional health, and self-reported health-related quality of life (HRQOL). Descriptive statistics and group comparisons were performed.

Results

A total of 104 patients with median age of 55 [49-64] years, 54% male, and median SOFA score of 10 [8-12] were analyzed. Incidence of AKI during ICU admission was 61 and 19.2% of patients required renal replacement therapy (RRT). Patients with AKI stage 2 or 3 (vs. those with AKI stage 1 or no AKI) walked less on the 6-min walk test (223 ± 132 vs. 295 ± 153 m, p = 0.059) and achieved lower of the predicted walk distance (38% vs. 58%, p = 0.041). Similar patterns of worse physical function and more significant muscle weakness were observed in multiple tests, with overall worse metrics in patients that required RRT. Patients with AKI stage 2 or 3 also reported lower HRQOL scores when compared to their counterparts, including less ability to return to work or hobby, or reengage in driving. There were no significant differences in cognitive function or emotional health between groups.

Conclusions

Survivors of critical illness and AKI stage 2 or 3 have increased physical debility and overall lower quality of life, with more impairment in return to work, hobby, and driving when compared to their counterparts without AKI or AKI stage 1 at 3 months post-discharge.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02749-z.

Association Between the Severity of Early Acute Kidney Injury and Subsequent in-Hospital Complications and 90-Day Mortality in Geriatric Patients Receiving Invasive Mechanical Ventilation

Purpose

Acute kidney injury (AKI) in elderly patients is associated with higher hospital mortality. However, the relationship between AKI and peri-intubation complications is unclear.

Methods

This retrospective, observational, multicenter cohort study enrolled 3271 consecutive elderly patients (≥75 years) who received invasive mechanical ventilation (MV) in four medical centers of Chinese PLA General Hospital from 2008 to 2020. AKI was diagnosed according to the 2012 KDIGO criteria by an absolute increase in serum creatinine of ≥26.5 µmol/L within the first 48 hours of MV. We recorded subsequent in-hospital complications, including incident gastrointestinal bleeding, new-onset electrolyte imbalances, severe hypoxemia, hypoalbuminemia, cardiovascular instability and all-cause 90-day mortality.

Results

A total of 1292 patients were included in the final evaluation, with 29.1% presenting AKI (stage 1: 31.4%, stage 2: 35.1%, stage 3: 33.5%). Multiple regression analyses show that more advanced AKI increased the risk of MAP <65 mmHg (stage 1: OR=1.833, P=0.002; stage 2: OR= 4.653, P<0.001; stage 3: OR=4.834, P<0.001) and SBP <90 mmHg (stage 1: OR=1.644, P=0.014; stage 2: OR=3.701, P<0.001; stage 3: OR=5.750, P<0.001), a new need for or requiring an increased dose of vasopressors (stage 1: OR=1.623, P=0.014; stage 2: OR=3.250, P<0.001; stage 3: OR=12.132, P<0.001), gastrointestinal bleeding (stage 1: OR=1.102, P=0.669; stage 2: OR=1.471, P=0.060; stage 3: OR=2.377, P<0.001), severe hypoxia (stage 1: OR=1.213, P=0.399; stage 2: OR=1.449, P=0.077; stage 3: OR=2.214, P<0.001) and all-cause 90-day mortality (stage 1: OR =0.935; P=0.741; stage 2: OR=1.888; P=0.001; stage 3: OR=12.584; P<0.001).

Conclusion

Our study suggests that the presence of AKI within the first 48 hours of MV in geriatric patients is associated with a higher risk for postintubation complications and 90-day mortality. Moreover, the risk of complications was greater for patients with more severe AKI.

Association of serum potassium level with early and late mortality in very elderly patients with acute kidney injury

Background

The kidneys play a central role in serum potassium (K ⁺) homeostasis, and their dysfunction leads to electrolyte disorders. We aimed to examine the relationship between different levels of K ⁺ and mortality among very elderly patients with acute kidney injury (AKI).

Methods

We retrospectively enrolled very elderly patients (≥75 years) with AKI from the hospital information system of the Chinese PLA General Hospital from January 1, 2007 to December 31, 2018. All-cause mortality was examined according to six predefined K ⁺ levels: <3.50 mmol/L, 3.50-3.79 mmol/L, 3.80-4.09 mmol/L, 4.10-4.79 mmol/L, 4.80-5.49 mmol/L, and ≥5.50 mmol/L. We estimated the risk of all-cause mortality using the multivariable adjusted Cox proportional hazard model with the normal K ⁺ level at 3.50-3.79 mmol/L as a reference.

Results

In total, 747 patients were deemed suitable for the final evaluation. The median age of the 747 participants was 88 (84-91) years. After 90 days, the mortality rates in the six strata were 28.3%, 21.9%, 30.1%, 35.4%, 45.2%, and 58.3%, respectively. In the multivariable adjusted analysis, patients with K ⁺ levels of 4.10-4.79 mmol/L (hazard ratio [HR]: 1.638; 95% confidence interval [CI]: 1.016-2.642), 4.80-5.49 mmol/L (HR: 2.585; 95% CI: 1.524-4.384), and ≥5.50 mmol/L (HR: 2.587; 95% CI: 1.495-4.479) had an increased risk of all-cause mortality. After 1 year, the mortality rates in the six strata were 44.8%, 41.1%, 45.1%, 51.8%, 63.1%, and 76.3%, respectively. In the multivariable adjusted analysis, patients with K ⁺ levels of 4.10-4.79 mmol/L (HR: 1.452; 95% CI: 1.014-2.079), 4.80-5.49 mmol/L (HR: 2.151; 95% CI: 1.427-3.241), and ≥5.50 mmol/L (HR: 2.341; 95% CI: 1.514-3.620) had an increased risk of all-cause mortality.

Conclusion

Increased serum K ⁺ levels, including levels of 4.10-5.49 mmol/L and ≥5.50 mmol/L, were associated with a significantly increased short- and long-term risk of death. Serum K ⁺ has the potential to be a marker of disease severity among very elderly patients with AKI.

Rehabilitation of a Patient With Minimal Change Nephrotic Syndrome and Acute Kidney Injury: A Case Report

Patients with minimal change nephrotic syndrome (MCNS) are prone to loss of motor skills due to urinary protein leakage, steroid myopathy, and other factors. Acute kidney injury (AKI) is a common complication that contributes to the loss of physical function. Rehabilitation is crucial, but its efficacy and safety are unknown. Here we present a case of a patient with MCNS complicated by AKI, who commenced rehabilitation after dialysis was discontinued and experienced improved mobility. The patient, a woman in her 70s, was admitted to our hospital with bilateral lower limb edema and decreased urine output for approximately 5 days. Treatment with prednisolone and furosemide was initiated, but then dialysis was initiated due to AKI. Rehabilitation was started after dialysis was discontinued. The patient's muscle strength and physical activity improved, and her exercise capacity and exercise tolerance improved without adverse effects. Rehabilitation may contribute to the improvement of exercise capacity without worsening renal function and urinary protein in patients with MCNS complicated by AKI.

Timing of renal-replacement therapy in intensive care unit-related acute kidney injury

PURPOSE OF REVIEW

The optimal timing of renal-replacement therapy (RRT) initiation for the management of acute kidney injury (AKI) in the intensive care unit (ICU) is frequently controversial. An earlier-strategy has biological rationale, even in the absence of urgent indications; however, a delayed-strategy may prevent selected patients from receiving RRT and avoid complications related to RRT.

RECENT FINDINGS

Previous studies assessing the optimal timing of RRT initiation found conflicting results, contributing to variation in clinical practice. The recent multinational trial, standard vs. accelerated initiation of renal replacement therapy in acute kidney injury (STARRT-AKI) found no survival benefit and a higher risk of RRT dependence with an accelerated compared to a standard RRT initiation strategy in critically ill patients with severe AKI. Nearly 40% of patients allocated to the standard-strategy group did not receive RRT. The Artificial Kidney Initiation in Kidney Injury-2 (AKIKI-2) trial further assessed delayed compared to more-delayed strategies for RRT initiation. The more-delayed strategy did not confer an increase in RRT-free days and was associated with a higher risk of death.

SUMMARY

Early preemptive initiation of RRT in critically ill patients with AKI does not confer clear clinical benefits. However, protracted delays in RRT initiation may be harmful.

Defining Acute Kidney Injury

Acute kidney injury (AKI) is a syndrome of impaired kidney function associated with reduced survival and increased morbidity. International consensus criteria were developed based on changes in serum creatinine and urine output. Based on these definitions, epidemiologic studies have shown strong associations with clinical outcomes including death and dialysis. However, numerous limitations exist for creatinine and urine volume as markers of AKI and novel biomarkers have been developed to detect cellular stress or damage. Persistent AKI and acute kidney disease are relatively new concepts that explore the idea of AKI as a continuum with chronic kidney disease.

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.

Urinary neprilysin for early detection of acute kidney injury after cardiac surgery: A prospective observational study

BACKGROUND

Acute kidney injury (AKI) predicts adverse outcomes after cardiac surgery. The accuracy of using changes in serum creatinine for diagnosis and grading of AKI is limited in the peri-operative cardiac surgical setting and AKI may be underdiagnosed due to haemodilution from cardiopulmonary bypass priming and the need for intra-operative and postoperative volume resuscitation.

OBJECTIVES

To determine whether the urinary biomarker neprilysin can be used as a marker for the early detection of AKI after cardiac surgery.

DESIGN

Prospective, observational cohort study.

SETTING

Austrian tertiary referral centre.

PATIENTS

96 Patients undergoing elective cardiac surgery with cardiopulmonary bypass.

MAIN OUTCOME MEASURES

Differences and discriminatory power of neprilysin levels early after cardiac surgery and on postoperative day 1 between patients with or without AKI, as defined by the Kidney Disease Improving Global Outcomes Group.

RESULTS

AKI was found in 27% (n=26). The median neprilysin levels on postoperative day 1 were significantly higher in the AKI than in the non-AKI group, 4.0 [interquartile range (IQR): 2 to 6.25] vs. 2.0 ng ml [IQR: 1.0 to 4.5], P = 0.0246, respectively. In addition, the median neprilysin levels at the end of surgery were significantly different between both groups, 5.0 [IQR: 2.0 to 9.0] vs. 2.0 ng ml [IQR: 1.0 to 4.0], P = 0.0055, respectively. The discriminatory power of neprilysin for detecting early AKI corresponded to an area under the curve of 0.77 (95% confidence interval, 0.65 to 0.90).

CONCLUSION

Urinary neprilysin has potential as a biomarker for the early detection of AKI after cardiac surgery and has comparable discriminatory power to recently studied AKI biomarkers.

TRIAL REGISTRATION

The trial was registered at ClinicalTrials.gov (NCT03854825, https://clinicaltrials.gov/ct2/show/NCT03854825).

Frailty status among older critically ill patients with severe acute kidney injury

BACKGROUND

Frailty status among critically ill patients with acute kidney injury (AKI) is not well described despite its importance for prognostication and informed decision-making on life-sustaining therapies. In this study, we aim to describe the epidemiology of frailty in a cohort of older critically ill patients with severe AKI, the outcomes of patients with pre-existing frailty before AKI and the factors associated with a worsening frailty status among survivors.

METHODS

This was a secondary analysis of a prospective multicentre observational study that enrolled older (age > 65 years) critically ill patients with AKI. The clinical frailty scale (CFS) score was captured at baseline, at 6 months and at 12 months among survivors. Frailty was defined as a CFS score of ≥ 5. Demographic, clinical and physiological variables associated with frailty as baseline were described. Multivariable Cox proportional hazard models were constructed to describe the association between frailty and 90-day mortality. Demographic and clinical factors associated with worsening frailty status at 6 months and 12 months were described using multivariable logistic regression analysis and multistate models.

RESULTS

Among the 462 patients in our cohort, median (IQR) baseline CFS score was 4 (3-5), with 141 (31%) patients considered frail. Pre-existing frailty was associated with greater hazard of 90-day mortality (59% (n = 83) for frail vs. 31% (n = 100) for non-frail; adjusted hazards ratio [HR] 1.49; 95% CI 1.11-2.01, p = 0.008). At 6 months, 68 patients (28% of survivors) were frail. Of these, 57% (n = 39) were not classified as frail at baseline. Between 6 and 12 months of follow-up, 9 (4% of survivors) patients transitioned from a frail to a not frail status while 10 (4% of survivors) patients became frail and 11 (5% of survivors) patients died. In multivariable analysis, age was independently associated with worsening CFS score from baseline to 6 months (adjusted odds ratio [OR] 1.08; 95% CI 1.03-1.13, p = 0.003).

CONCLUSIONS

Pre-existing frailty is an independent risk factor for mortality among older critically ill patients with severe AKI. A substantial proportion of survivors experience declining function and worsened frailty status within one year.

Serum Sodium Levels Predict Mortality in Elderly Acute Kidney Injury Patients: A Retrospective Observational Study

Purpose

We examined the relationship between different levels of serum sodium and mortality among elderly patients with acute kidney injury (AKI).

Methods

We retrospectively enrolled elderly patients from Chinese PLA General Hospital from 2007, to 2018. All-cause mortality was examined according to eight predefined sodium levels: <130.0 mmol/L, 130.0–134.9 mmol/L, 135.0–137.9 mmol/L, 138.0–141.9 mmol/L, 142.0–144.9 mmol/L, 145.0–147.9 mmol/L, 148.0–151.9 mmol/L, and ≥152.0 mmol/L. We estimated the risk of all-cause mortality using a multivariable adjusted Cox analysis, with a normal sodium level of 135.0–137.9 mmol/L as a reference.

Results

In total, 744 patients were suitable for the final evaluation. After 90 days, the mortality rates in the eight strata were 36.1, 27.8, 19.6, 24.4, 30.7, 48.6, 52.8, and 57.7%, respectively. In the multivariable adjusted analysis, patients with sodium levels <130.0 mmol/L (HR: 2.247; 95% CI: 1.117–4.521), from 142.0 to 144.9 mmol/L (HR: 1.964; 95% CI: 1.100–3.508), from 145.0 to 147.9 mmol/L (HR: 2.942; 95% CI: 1.693–5.114), from 148.0 to 151.9 mmol/L (HR: 3.455; 95% CI: 2.009–5.944), and ≥152.0 mmol/L (HR: 3.587; 95% CI: 2.151–5.983) had an increased risk of all-cause mortality. After 1 year, the mortality rates in the eight strata were 58.3, 47.8, 33.7, 38.9, 45.5, 64.3, 69.4, and 78.4%, respectively. Patients with sodium levels <130.0 mmol/L (HR: 1.944; 95% CI: 1.125–3.360), from 142.0 to 144.9 mmol/L (HR: 1.681; 95% CI: 1.062–2.660), from 145.0 to 147.9 mmol/L (HR: 2.631; 95% CI: 1.683–4.112), from 148.0 to 151.9 mmol/L (HR: 2.411; 95% CI: 1.552–3.744), and ≥152.0 mmol/L (HR: 3.037; 95% CI: 2.021–4.563) had an increased risk of all-cause mortality.

Conclusion

Sodium levels outside the interval of 130.0–141.9 mmol/L were associated with increased risks of 90-day mortality and 1-year mortality in elderly AKI patients.

Clinical Knowledge Supported Acute Kidney Injury (AKI) Risk Assessment Model for Elderly Patients

From the clinical viewpoint, the statistical approach is still the cornerstone for exploring many diseases. This study was conducted to explore the risk factors related to acute kidney injury (AKI) for elderly patients using the multiple criteria decision-making (MCDM) approach. Ten nephrologists from a teaching hospital in Taipei took part in forming the AKI risk assessment model. The key findings are: (1) Comorbidity and Laboratory Values would influence Comprehensive Geriatric Assessment; (2) Frailty is the highest influential AKI risk factor for elderly patients; and (3) Elderly patients could enhance their daily activities and nutrition to improve frailty and lower AKI risk. Furthermore, we illustrate how to apply MCDM methods to retrieve clinical experience from seasoned doctors, which may serve as a knowledge-based system to support clinical prognoses. In conclusion, this study has shed light on integrating multiple research approaches to assist medical decision-making in clinical practice.

Care of the Survivor of Critical Illness and Acute Kidney Injury: A Multidisciplinary Approach

Acute kidney injury (AKI) is a common complication of critical illness and is associated with adverse short- and long-term health consequences. Survivors of critical illness and AKI experience poor kidney, cardiovascular and quality of life outcomes, along with increased mortality. Yet, many patients surviving AKI are unaware that there is a problem with their kidney health, and post-AKI nephrology follow-up occurs at very low rates. Although there is a paucity of evidence-based studies to guide post-AKI care, attention to risk factors such as hypertension and albuminuria are requisite. There are several ongoing or planned studies which are expected to help inform specific management in the future. Until then, a multidisciplinary approach is warranted to address areas such as quality of life, physical rehabilitation, dietary modifications, and medication reconciliation.

Regular exercise and branched-chain amino acids prevent ischemic acute kidney injury-related muscle wasting in mice

Acute kidney injury (AKI) causes glucose and protein metabolism abnormalities that result in muscle wasting, thereby affecting the long-term prognosis of critical illness survivors. Here, we examined whether early intervention with treadmill exercise and branched-chain amino acids (BCAA) can prevent AKI-related muscle wasting and reduced physical performance in mice. Unilateral 15 min ischemia-reperfusion injury was induced in contralateral nephrectomized mice, and muscle histological and physiological changes were assessed and compared with those of pair-fed control mice, since AKI causes severe anorexia. Mice exercised for 30 min each day and received oral BCAA for 7 days after AKI insult. By day 7, ischemic AKI significantly decreased wet weight, myofiber cross-sectional area, and central mitochondrial volume density of the anterior tibialis muscle, and significantly reduced maximal exercise time. Regular exercise and BCAA prevented AKI-related muscle wasting and low physical performance by suppressing myostatin and atrogin-1 mRNA upregulation, and restoring reduced phosphorylated Akt and PGC-1α mRNA expression in the muscle. Ischemic AKI induces muscle wasting by accelerating muscle protein degradation and reducing protein synthesis; however, we found that regular exercise and BCAA prevented AKI-related muscle wasting without worsening kidney damage, suggesting that early rehabilitation with nutritional support could prevent AKI-related muscle wasting.

Association of acute kidney injury with frailty in elderly population: a systematic review and meta-analysis

Aim: The objective of this study was to assess whether an elderly patient's frailty was associated with acute kidney injury (AKI) and to examine whether severe frailty group had an increased risk of AKI than mild-moderate group.Methods: We searched The Cochrane Library, PubMed, and EMBASE for relevant studies without language limitations before 1 March 2019 with a priori defined inclusion and exclusion criteria. Five population-based cohort studies were included for systematic review and meta-analysis.Results: Compared with the control group, the frailty group is significantly associated AKI (Odds Ratio = 2.05; 95% CI: 1.23-3.43). The moderate-severe frailty group has an increased risk of AKI than mild frailty group (Hazard Ratio = 2.87; 95% CI: 1.60-5.17.Conclusion: In conclusion, the available best evidence support an association between frailty and AKI among elder patients, thus relevant interventions should be taken among elderly under potential risk of AKI.

Long-term outcomes of acute kidney injury and strategies for improved care

Acute kidney injury (AKI), once viewed predominantly as a self-limited and reversible condition, is now recognized as a growing problem associated with significant risks of adverse long-term health outcomes. Many cohort studies have established important relationships between AKI and subsequent risks of recurrent AKI, hospital re-admission, morbidity and mortality from cardiovascular disease and cancer, as well as the development of chronic kidney disease and end-stage kidney disease. In both high-income countries (HICs) and low-income or middle-income countries (LMICs), several challenges exist in providing high-quality, patient-centered care following AKI. Despite advances in our understanding about the long-term risks following AKI, large gaps in knowledge remain about effective interventions that can improve the outcomes of patients. Therapies for high blood pressure, glycaemic control (for patients with diabetes), renin-angiotensin inhibition and statins might be important in improving long-term cardiovascular and kidney outcomes after AKI. Novel strategies that incorporate risk stratification approaches, educational interventions and new models of ambulatory care following AKI have been described, and some of these are now being implemented and evaluated in clinical studies in HICs. Care for AKI in LMICs must overcome additional barriers due to limited resources for diagnosis and management.

Under-recognized post-stroke acute kidney injury: risk factors and relevance for stroke outcome of a frequent comorbidity

BACKGROUND

Acute kidney injury (AKI) is emerging as a predictor of poor stroke outcome, however, it is often not recognized. The aim of our study was to evaluate post-stroke AKI burden, AKI risk factors and their influence in post-stroke outcome.

METHODS

From 2013 to 2016, 440 individuals with stroke diagnosis admitted in Stroke Unit, Foundation IRCCS Policlinico San Matteo (Pavia, Italy), were retrospectively enrolled. AKI cases identified by KDIGO criteria through the electronic database and hospital chart review were compared with the ones reported in discharge letters or in administrative hospital data base. Mortality data were provided by Agenzia Tutela della Salute of Pavia.

RESULTS

We included 430 patients in the analysis. Median follow-up was 19.2 months. We identified 79 AKI cases (18% of the enrolled patients, 92% classified as AKI stage 1), a fivefold higher number of cases than the ones reported at discharge. 37 patients had AKI at the admission in the hospital, while 42 developed AKI during the hospitalization. Cardioembolic (p = 0.01) and hemorrhagic (p = 0.01) stroke types were associated with higher AKI risk. Admission National Institutes of Health Stroke Scale (NIHSS, p < 0.05) and Charlson Comorbidity Index (p < 0.01) were independently associated with overall AKI, while admission NIHSS (p < 0.05) and eGFR (p < 0.005) were independently associated with AKI developed during the hospitalization. AKI was associated to longer in-hospital stay (p = 0.01), worse Rankin Neurologic Disability Score at discharge (p < 0.0001) and discharge disposition other than home (p = 0.03). AKI was also independently associated to higher in-hospital mortality (OR 3.9 95% CI 1.2-12.9 p = 0.023) but not with long-term survival.

CONCLUSIONS

Post-stroke AKI diagnosis needs to be improved by strictly monitoring individuals with cardioembolic or hemorrhagic stroke, reduced kidney function, higher Charlson Comorbidity Index and worse NIHSS at presentation.

The association between heat stroke and subsequent cardiovascular diseases

Background

Recent studies have indicated that several critical illnesses are associated with an increased risk of cardiovascular diseases (CVDs). Nonetheless, studies of the association between heat-related illnesses (HRIs) and subsequent CVDs are still limited. We sought to evaluate whether heat stroke (HS) was associated with an increased CVD incidence.

Methods

The data from the nationwide, population-based, retrospective, cohort study described herein were obtained from the National Health Insurance Research Database in Taiwan. The outcome evaluated in this study was the cumulative incidence of CVDs, which was compared between patients with HS, patients with other HRIs and a control group during a 14-year follow-up period.

Results

Our analyses included 150 HS cases, 150 patients with other HRIs and 150 patients without HRIs. The HS patients had a significantly higher incidence of developing CVDs than the other HRI and control patients (32.67% vs. 23.33% vs. 16.67%, p = 0.005). Patients with HS had an increased incidence of acute myocardial infarction (AMI) compared with that of the controls (6% vs. 2.67%, p = 0.042) and an increased incidence of acute ischemic stroke (AIS) compared with those of the other HRI and control patients (12% vs. 6% vs. 4.67%, p = 0.038). An increased risk of chronic kidney disease (CKD) was also found in the patients with HS and other HRIs compared to that in the controls (17.33% vs. 14.67% vs. 6.67%, p = 0.016).

Conclusion

Prior HS was associated with an increased incidence of CVDs, particularly AMI and AIS, and an increased incidence of CKD.

Low Blood ALT Activity and High FRAIL Questionnaire Scores Correlate with Increased Mortality and with Each Other. A Prospective Study in the Internal Medicine Department

Background: Low blood ALT, Alanine aminotransferase activity and high FRAIL (Fatigue, Resistance, Ambulation, Illnesses and Loss of Weight) questionnaire scores were previously shown to be associated with frailty and increased risk of mortality. We aimed to correlate these tools with mortality and each other in patients hospitalized in an internal medicine department. Methods: This is a prospective study in a large tertiary hospital. We assessed the predictive value for clinical outcomes of both low ALT blood activity and the pre-frail and frail categories of the “FRAIL” questionnaire. Results: During a 15 months study, 179 consecutive patients were recruited, of whom 20 died. When all study participants were divided to three groups according to admission ALT levels (below 10 IU/L, 11 to 19 IU/L and above 20 IU/L) we found a statistically significant difference in the rate of mortality: 4 patients died within the group of ALT < 10 IU/L, 14 patients died in the group of 10 IU/L < ALT < 19 IU/L and in the group of patients with ALT > 20 IU/L, only 2 patients died (p = 0.042). A higher score on the FRAIL questionnaire was associated, with statistical significance, with higher risk of mortality (p = 0.029). There was a significant correlation (p = 0.038) between blood ALT activity and the pre-frailty and frailty classifications by the FRAIL Questionnaire. Conclusions: Both the FRAIL questionnaire and blood ALT activity are simple and practical tools for frailty assessment and risk stratification of patients hospitalized in the internal medicine department. Both tool’s results also correlate with each other.

Modelling physical resilience in ageing mice

Geroprotectors, a class of drugs targeting multiple deficits occurring with age, necessitate the development of new animal models to test their efficacy. The COST Action MouseAGE is a European network whose aim is to reach consensus on the translational path required for geroprotectors, interventions targeting the biology of ageing. In our previous work we identified frailty and loss of resilience as a potential target for geroprotectors. Frailty is the result of an accumulation of deficits, which occurs with age and reduces the ability to respond to adverse events (physical resilience). Modelling frailty and physical resilience in mice is challenging for many reasons. There is no consensus on the precise definition of frailty and resilience in patients or on how best to measure it. This makes it difficult to evaluate available mouse models. In addition, the characterization of those models is poor. Here we review potential models of physical resilience, focusing on those where there is some evidence that the administration of acute stressors requires integrative responses involving multiple tissues and where aged mice showed a delayed recovery or a worse outcome then young mice in response to the stressor. These models include sepsis, trauma, drug- and radiation exposure, kidney and brain ischemia, exposure to noise, heat and cold shock.