How can we define recovery after acute kidney injury? Considerations from epidemiology and clinical trial design

Unsupervised clustering identifies sub-phenotypes and reveals novel outcome predictors in patients with dialysis-requiring sepsis-associated acute kidney injury

INTRODUCTION

Heterogeneity exists in sepsis-associated acute kidney injury (SA-AKI). This study aimed to perform unsupervised consensus clustering in critically ill patients with dialysis-requiring SA-AKI.

PATIENTS AND METHODS

This prospective observational cohort study included all septic patients, defined by the Sepsis-3 criteria, with dialysis-requiring SA-AKI in surgical intensive care units in Taiwan between 2009 and 2018. We employed unsupervised consensus clustering based on 23 clinical variables upon initializing renal replacement therapy. Multivariate-adjusted Cox regression models and Fine-Gray sub-distribution hazard models were built to test associations between cluster memberships with mortality and being free of dialysis at 90 days after hospital discharge, respectively.

RESULTS

Consensus clustering among 999 enrolled patients identified three sub-phenotypes characterized with distinct clinical manifestations upon renal replacement therapy initiation (n = 352, 396 and 251 in cluster 1, 2 and 3, respectively). They were followed for a median of 48 (interquartile range 9.5-128.5) days. Phenotypic cluster 1, featured by younger age, lower Charlson Comorbidity Index, higher baseline estimated glomerular filtration rate but with higher severity of acute illness was associated with an increased risk of death (adjusted hazard ratio of 3.05 [95% CI, 2.35-3.97]) and less probability to become free of dialysis (adjusted sub-distribution hazard ratio of 0.55 [95% CI, 0.38-0.8]) than cluster 3. By examining distinct features of the sub-phenotypes, we discovered that pre-dialysis hyperlactatemia ≥3.3 mmol/L was an independent outcome predictor. A clinical model developed to determine high-risk sub-phenotype 1 in this cohort (C-static 0.99) can identify a sub-phenotype with high in-hospital mortality risk (adjusted hazard ratio of 1.48 [95% CI, 1.25-1.74]) in another independent multi-centre SA-AKI cohort.

CONCLUSIONS

Our data-driven approach suggests sub-phenotypes with clinical relevance in dialysis-requiring SA-AKI and serves an outcome predictor. This strategy represents further development toward precision medicine in the definition of high-risk sub-phenotype in patients with SA-AKI.Key messagesUnsupervised consensus clustering can identify sub-phenotypes of patients with SA-AKI and provide a risk prediction.Examining the features of patient heterogeneity contributes to the discovery of serum lactate levels ≥ 3.3 mmol/L upon initializing RRT as an independent outcome predictor.This data-driven approach can be useful for prognostication and lead to a better understanding of therapeutic strategies in heterogeneous clinical syndromes.

Development and validation of clinical prediction models for acute kidney injury recovery at hospital discharge in critically ill adults

PURPOSE

Acute kidney injury (AKI) recovery prediction remains challenging. The purpose of the present study is to develop and validate prediction models for AKI recovery at hospital discharge in critically ill patients with ICU-acquired AKI stage 3 (AKI-3).

METHODS

Models were developed and validated in a development cohort (n = 229) and a matched validation cohort (n = 244) from the multicenter EPaNIC database to create prediction models with the least absolute shrinkage and selection operator (Lasso) machine-learning algorithm. We evaluated the discrimination and calibration of the models and compared their performance with plasma neutrophil gelatinase-associated lipocalin (NGAL) measured on first AKI-3 day (NGAL_AKI3) and reference model that only based on age.

RESULTS

Complete recovery and complete or partial recovery occurred in 33.20% and 51.23% of the validation cohort patients respectively. The prediction model for complete recovery based on age, need for renal replacement therapy (RRT), diagnostic group (cardiac/surgical/trauma/others), and sepsis on admission had an area under the receiver operating characteristics curve (AUROC) of 0.53. The prediction model for complete or partial recovery based on age, need for RRT, platelet count, urea, and white blood cell count had an AUROC of 0.61. NGAL_AKI3 showed AUROCs of 0.55 and 0.53 respectively. In cardiac patients, the models had higher AUROCs of 0.60 and 0.71 than NGAL_AKI3's AUROCs of 0.52 and 0.54. The developed models demonstrated a better performance over the reference models (only based on age) for cardiac surgery patients, but not for patients with sepsis and for a general ICU population.

CONCLUSION

Models to predict AKI recovery upon hospital discharge in critically ill patients with AKI-3 showed poor performance in the general ICU population, similar to the biomarker NGAL. In cardiac surgery patients, discrimination was acceptable, and better than NGAL. These findings demonstrate the difficulty of predicting non-reversible AKI early.

Prognostic value of serum levels of multiple adhesion factors in patients with sepsis-induced acute kidney injury

Background

Acute kidney injury (AKI) is common in patients with sepsis and septic shock. Urine output and serum creatinine (SCr) levels are the criteria for diagnosing AKI. However, the application of these levels in the diagnosis of AKI has limitations.

Objective

To detect the expression of various adhesion factors in different stages of AKI as defined by Kidney Disease: Improving Global Outcomes (KDIGO) and to analyse their relationship with the prognosis of patients with sepsis-induced AKI (S-AKI).

Methods

Adult patients with sepsis who were admitted to the hospital between June 2019 and May 2020 were included. Of 90 adult patients with sepsis, 58 had S-AKI. Sixty-seven subjects without sepsis were used as controls. Enzyme-linked immunosorbent assay kits were used to measure E-selectin (CD62E), L-selectin (CD62L), P-selectin, intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), and their relationship with the prognosis of patients with S-AKI patients was analysed. Receiver operating characteristic curves were used to analyse the predictive value of different adhesion factors on renal resistance index and renal function recovery. Multivariate logistic regression analysis was used to identify factors associated with renal recovery.

Results

The expression of CD62L was significantly higher in S-AKI patients than in non-AKI patients with sepsis. Compared with the non-AKI group, Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment scores were significantly higher in the AKI group than in the non-AKI group (P < 0.05). Mean blood pressure, SCr levels and procalcitonin levels were higher in the AKI group than in the non-AKI group (P < 0.05 for all). The CD62L levels decreased with increasing S-AKI stage. The CD62E levels were highest in S-AKI stage 2, and the VCAM-1 levels were highest in S-AKI stage 3. All patients with S-AKI were followed up with for 28 days. The results found that VCAM-1 was the best predictor of renal recovery in patients with S-AKI.

Conclusion

CD62L is an indicator of S-AKI stage1, and CD62E is an indicator of S-AKI stage 2. In addition, VCAM-I demonstrated satisfactory performance in predicting early recovery of renal function in patients with S-AKI.

Timely renal replacement therapy linked to better outcome in patients with sepsis-associated acute kidney injury

Background

Recent studies suggest that acute kidney injury (AKI) can be treated with renal replacement therapy (RRT). However, its benefits to patients with sepsis-associated AKI (SA-AKI), which is linked to high mortality and morbidity rates, remain under debate. The aim of this study was to compare the outcomes of different RRT strategies for patients with SA-AKI.

Methods

This retrospective study evaluated patients who were admitted to the hospital with sepsis and developed SA-AKI during hospitalization from 1st January 2014 to 31st January 2019. Mortality, renal recovery, and systemic organ function at 90 days following admission were compared between the RRT group (RG) and non-RRT group (NRG), as well as the early-RRT group (EG) and delayed-RRT group (DG). The groups were defined according to the time from admission to RRT initiation (criterion 1, EG1 and DG1) and Kidney Disease Improving Global Outcomes (KDIGO) classification (criterion 2, EG2 and DG2). Categorical and continuous variables were compared using the chi-squared test or Fisher's exact test and Student's t-test or Wilcoxon test. Kaplan-Meier curves were constructed to determine the unadjusted survival rates for the different subgroups.

Results

A total of 116 patients were included in this study; of those, 38 received RRT and 46 expired within 90 days. Among different strategies of RRT, there were no significant differences found in 90-day mortality (RG vs. NRG: χ²=0.610, P=0.435; EG1 vs. DG1: χ² =0.835, P=0.360; EG2 vs. DG2: χ²=0.022, P=0.899) and renal recovery. However, the values of change in sequential organ failure assessment (ΔSOFA)_max-min of patients in the EG and RG were significantly higher than those recorded in the NRG (ΔSOFA_RG=7.0, ΔSOFA_NRG=3.60, ΔSOFA_EG1=9.00, ΔSOFA_EG2=6.30; P<0.050). Also, the 90-day renal recovery in the EG was better than that noted in the DG with criterion 1 (87.5% vs. 38.5%, respectively, χ²=10.425, P=0.032), suggesting that RRT (especially timely RRT) may be beneficial to the restoration of systemic organ function in patients with SA-AKI.

Conclusion

RRT did not reduce the 90-day mortality among patients with SA-AKI. However, timely RRT may benefit the restoration of systemic organ function, thereby improving the quality of life of patients.

Experimental Aristolochic Acid Nephropathy: A Relevant Model to Study AKI-to-CKD Transition

Aristolochic acid nephropathy (AAN) is a progressive tubulointerstitial nephritis caused by the intake of aristolochic acids (AA) contained in Chinese herbal remedies or contaminated food. AAN is characterized by tubular atrophy and interstitial fibrosis, characterizing advanced kidney disease. It is established that sustained or recurrent acute kidney injury (AKI) episodes contribute to the progression of CKD. Therefore, the study of underlying mechanisms of AA-induced nephrotoxicity could be useful in understanding the complex AKI-to-CKD transition. We developed a translational approach of AKI-to-CKD transition by reproducing human AAN in rodent models. Indeed, in such models, an early phase of acute tubular necrosis was rapidly followed by a massive interstitial recruitment of activated monocytes/macrophages followed by cytotoxic T lymphocytes, resulting in a transient AKI episode. A later chronic phase was then observed with progressive tubular atrophy related to dedifferentiation and necrosis of tubular epithelial cells. The accumulation of vimentin and αSMA-positive cells expressing TGFβ in interstitial areas suggested an increase in resident fibroblasts and their activation into myofibroblasts resulting in collagen deposition and CKD. In addition, we identified 4 major actors in the AKI-to-CKD transition: (1) the tubular epithelial cells, (2) the endothelial cells of the interstitial capillary network, (3) the inflammatory infiltrate, and (4) the myofibroblasts. This review provides the most comprehensive and informative data we were able to collect and examines the pending questions.

Acute Kidney Injury Recovery Patterns in ST-Segment Elevation Myocardial Infarction Patients

Background: Acute kidney injury (AKI) is a frequent complication in patients with ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI). Identification of different AKI recovery patterns may improve patient prognostic stratification. We investigated the clinical relevance of AKI recovery patterns among STEMI patients undergoing PCI. Methods: A retrospective study of 2943 STEMI patients undergoing PCI. The incidence of renal impairment, in-hospital complications, short and long-term mortality, were compared between patients without AKI, with early recovery defined as a return to baseline creatinine within 72 h, and no AKI recovery/delayed recovery defined as all other AKI cases. Results: A total of 255 (8.7%) patients developed AKI, of whom 124/255 (49%) patients had an early recovery, whereas 131/255 (51%) had no AKI recovery/delayed recovery. Patients without recovery were more likely to have in-hospital complications and higher long-term mortality (36.64% vs. 7.25%%; p < 0.001). In a multivariable regression model, the mortality hazard ratio (HR) for long term mortality remained significant for patients with no/delayed recovery AKI (HR 7.76, 95% CI 4.69 to 12.86, p < 0.001), and a strong trend among patients with resolving AKI (HR 2.09, 95% CI 0.933−4.687, p = 0.071). Conclusions: Among STEMI patients undergoing PCI, the recovery pattern of AKI is a valuable prognostic marker.

Anticipation of recovery of native renal function and liberation from renal replacement therapy in critically ill patients with severe acute kidney injury

Background

Renal replacement therapy (RRT) is used to manage critically ill patients with severe acute kidney injury (AKI-D), and it is undoubtedly life-sustaining for most patients. However, the prolonged unnecessary use of these techniques may be harmful. At present, no consensus guidelines provide specific recommendations for clinicians on when (optimal timing of discontinuation) and how (liberation or weaning) to stop RRT in intensive care unit (ICU) patients with recovering native kidney function.

Methods and results

Numerous variables such as clinical parameters, classical surrogate markers for glomerular filtration rate, novel biomarkers of kidney function and damage, and new imaging techniques in AKI-D have been described to predict successful discontinuation of RRT. Most available studies are limited by study design, heterogeneity of variable assessment and thresholds of biomarkers, and lack of prospective validation. At present, the decision on discontinuation of RRT in ICU patients is based on three clinical scenarios: (a) intrinsic kidney function (defined as spontaneous urine output > 500 ml/24 h, timed creatinine clearance > 15 to 20 ml/min) has adequately improved to match the demands and continued RRT is no longer consistent with goals of care (transition to intermittent RRT); (b) the acute illness that prompted RRT has improved; (c) the clinical practice of switching haemodynamic stable patients with persistent AKI-D from continuous RRTs to intermittent RRTs is variable, but de-escalation of RRT (frequency, dose) may facilitate mobilization and discharge of ICU patients.

Conclusions

The predictive ability of novel kidney biomarkers, surrogate markers of kidney function, and direct measurements of kidney function should be evaluated in future studies.

Predialysis serum lactate levels could predict dialysis withdrawal in Type 1 cardiorenal syndrome patients

BACKGROUND

Renal replacement therapy (RRT) is an effective rescue therapy for Type 1 cardiorenal syndrome (CRS). Previous studies have demonstrated that type 1 CRS patients with severe renal dysfunction were susceptible to sepsis, and that serum lactate has been correlated with the risk of mortality in patients with sepsis. However, the association between serum lactate level and the prognosis of type 1 CRS patients requiring RRT is unknown.

METHODS

An inception cohort of 500 type 1 CRS patients who received RRT in a tertiary-care referral hospital in Taiwan from August 2011 to January 2018 were enrolled. The outcomes of interest were dialysis withdrawal and 90-day mortality. The results were further externally validated using sampling data of type 1 CRS patients requiring dialysis from multiple tertiary-care centers.

FINDINGS

The 90-day mortality rate was 52.8% and the incidence rate of dialysis withdrawal was 34.8%. Lower pre-dialysis lactate was correlated with a higher rate of dialysis withdrawal and lower rate of mortality. Generalized additive model showed that 4.2 mmol/L was an adequate cut-off value of lactate to predict mortality. Taking mortality as a competing risk, Fine-Gray subdistribution hazard analysis further indicated that a low lactate level (≦ 4.2 mmol/L) was an independent predictor for the possibility of dialysis withdrawal, as also shown in external validation. The interaction of quick Sequential Organ Failure Assessment score and lactate was associated with dialysis dependence in a disease severity-dependent manner. Furthermore, the associations between hyperlactatemia and dialysis dependence were consistent in the patients with and without sepsis.

INTERPRETATION

Serum lactate level is accurate and capable of forecasting the prognosis along with qSOFA severity for clinical decision-making for treating type 1 CRS patients. Further studies are needed to validate our results.

FUNDING

This study was supported by grants from Taiwan National Science Council [104-2314-B-002-125-MY3,106-2314-B-002-166-MY3,107-2314-B-002-026-MY3], National Taiwan University Hospital [106-FTN20,106-P02,UN106-014,106-S3582,107-S3809,107-T02,PC1246,VN109-09,109-S4634,UN109-041], Ministry of Science and Technology of the Republic of China [MOST106-2321-B-182-002,106-2314-B-182A-064,MOST107-2321-B-182-004,MOST107-2314-B-182A-138, MOST108-2321-B-182-003,MOST109-2321-B-182-001, MOST108-2314-B-182A-027], Chang Gung Memorial Hospital [CMRPG-2G0361,CMRPG-2H0161,CMRPG-2J0261, CMRPG-2K0091], and Ministry of Health and Welfare of the Republic of China [PMRPG-2L0011].

Renal Outcomes of Dialysis-Dependent Acute Kidney Injury in Noncritically Ill Patients: A Retrospective Study

INTRODUCTION

Acute kidney injury (AKI) is a common complication among hospitalized patients, potentially affecting short- and long-term clinical outcomes. In this retrospective study, we evaluated renal outcomes in noncritically ill patients who required acute hemodialysis (HD) because of an AKI episode occurring during hospitalization.

METHODS

Sixty-three hemodynamically stable patients with AKI undergoing acute intermittent HD were included. Kidney function was evaluated at baseline control (pre-AKI), at AKI diagnosis and during the follow-up. According to serum creatinine and the estimated glomerular filtration rate (eGFR), we defined three clinical conditions: renal recovery, different stages of acute kidney disease (AKD), and chronic kidney disease (CKD).

RESULTS

Among the 63 patients evaluated, 34 patients (54%) had a history of CKD. Six patients (10%) presented early full renal recovery. HD treatment was stopped in 38 patients (60%), while 25 patients (40%) required maintenance HD. Dialysis-independent patients presented lower comorbidity and higher baseline eGFR and delta creatinine, compared to dialysis-dependent patients. Baseline CKD, previous AKI episodes, and parenchymal causes of AKI were associated with a significant risk of dialysis dependence. At 1-month control, 15 patients (39%) presented AKD stage 0, 6 patients (16%) AKD stage 1, and 17 patients (44%) AKD stage 2-3. At 3-month control, 29 out of 38 patients recovering from AKI (76%) presented CKD. AKD stage was significantly correlated with the risk of CKD development, which, resulted higher in patients with lower baseline eGFR.

CONCLUSIONS

AKI might represent a risk factor for the development of chronic kidney damage, even in noncritically ill patients.

Predicting successful continuous renal replacement therapy liberation in critically ill patients with acute kidney injury

PURPOSE

No standardized criteria for continuous renal replacement therapy (CRRT) liberation have been established. We sought to develop and internally validate prediction models for successful CRRT liberation in critically ill patients with acute kidney injury (AKI).

MATERIALS AND METHODS

This single-center, retrospective cohort study included adult patients admitted to intensive care units (ICUs) with AKI and treated with CRRT from January 1, 2007, to May 4, 2018, at a tertiary referral hospital. The cohort was randomly divided into derivation and validation sets. The outcomes were successful CRRT liberation, defined as renal replacement therapy (RRT)-free survival within 72 h after the liberation and hospital discharge. Multivariate logistic regression models were developed and internally validated.

RESULTS

Of 1135 AKI patients requiring CRRT, successful CRRT liberation and RRT-free survival at hospital discharge were observed in 228 (20%) and 395 (35%) individuals, respectively. The independent predictors included mean hourly urine output within 12 h before liberation, mean serum creatinine value within 24 h before liberation, cumulative fluid balance from ICU admission to liberation, CRRT duration before liberation, and the requirement of vasoactive agents within 24 h before liberation. The models demonstrated good discrimination (AUROC, 0.76 and 0.78; positive predictive value, 36% and 48%; negative predictive value, 92% and 94%; respectively) and calibration in the validation set.

CONCLUSIONS

These validated models could assist the decision-making related to the CRRT liberation in critically ill patients with AKI.

MicroRNA in Human Acute Kidney Injury: A Systematic Review Protocol

BACKGROUND

Acute kidney injury (AKI) is a common complication of hospitalization with high morbidity and mortality for which no effective treatments exist and for which current diagnostic tools have limitations for earlier identification. MicroRNAs (miRNAs) are small non-coding RNAs that have been implicated in the pathogenesis of AKI, and some miRNAs have shown promise as therapeutic tools in animal models of AKI. However, less is known about the role of miRNAs in human AKI.

OBJECTIVE

To evaluate the role of miRNAs in human subjects with AKI.

DESIGN

Systematic review and meta-analysis.

MEASUREMENTS

Quantification of miRNA levels from human blood, urine, or kidney biopsy samples, and measures of renal function as defined in the study protocol.

METHODS

A comprehensive search strategy for Ovid MEDLINE All, Embase, Web of Science, and CENTRAL will be developed to identify investigational studies that evaluated the relationship between miRNA levels and human AKI. Primary outcomes will include measurements of kidney function and miRNA levels. Study screening, review and data extraction will be performed independently by 2 reviewers. Study quality and certainty of evidence will be assessed with validated tools. A narrative synthesis will be included and the possibility for meta-analysis will be assessed according to characteristics of clinical and statistical heterogeneity between studies.

LIMITATIONS

These include (1) lack of randomized trials of miRNAs for the prevention or treatment of human AKI, (2) quality of included studies, and (3) sources of clinical and statistical heterogeneity that may affect strength and reproducibility of results.

CONCLUSION

Previous studies of miRNAs in different animal models of AKI have generated strong interest on their use for the prevention and treatment of human AKI. This systematic review will characterize the most promising miRNAs for human research and will identify methodological constraints from miRNA research in human AKI to help inform the design of future studies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020201253.

Long-term consequences of acute kidney injury: a narrative review

The incidence of acute kidney injury (AKI) has increased in the past decades. AKI complicates up to 15% of hospitalizations and can reach up to 50-60% in critically ill patients. Besides the short-term impact of AKI in patient outcomes, several studies report the association between AKI and adverse long-term outcomes, such as recurrent AKI episodes in 25-30% of cases, hospital re-admissions in up to 40% of patients, an increased risk of cardiovascular events, an increased risk of progression of chronic kidney disease (CKD) after AKI and a significantly increased long-term mortality. Despite the long-term impact of AKI, there are neither established guidelines on the follow-up care of AKI patients, nor treatment strategies to reduce the incidence of sequelae after AKI. Only a minority of patients have been referred to nephrology post-discharge care, despite the evidence of improved outcomes associated with nephrology referral by addressing cardiovascular risk and risk of progression to CKD. Indeed, AKI survivors should have specialized nephrology follow-up to assess kidney function after AKI, perform medication reconciliation, educate patients on nephrotoxic avoidance and implement strategies to prevent CKD progression. The authors provide a comprehensive review of the transition from AKI to CKD, analyse the current evidence on the long-term outcomes of AKI and describe predisposing risk factors, highlight the importance of follow-up care in these patients and describe the current therapeutic strategies which are being investigated on their impact in improving patient outcomes.

Targeted inhibition of Rev-erb-α/β limits ferroptosis to ameliorate folic acid-induced acute kidney injury

BACKGROUND AND PURPOSE

Acute kidney injury (AKI) is a common and critical illness, resulting in severe morbidity and a high mortality. There is a considerable interest in identifying novel molecular targets for management of AKI. We investigated the potential role of the circadian clock components Rev-erb-α/β in regulation of ferroptosis and AKI.

EXPERIMENTAL APPROACH

AKI model was established by treating mice with folic acid. Regulatory effects of Rev-erb-α/β on AKI and ferroptosis were determined using single-gene knockout (Rev-erb-α^-/- and Rev-erb-β^-/- ) mice, incomplete double-knockout (icDKO, Rev-erb-α^+/- Rev-erb-β^-/- ) mice and cells with erastin-induced ferroptosis. Targeted antagonism of Rev-erb-α/β to alleviate AKI and ferroptosis was assessed using the small-molecule antagonist SR8278. Transcriptional gene regulation was investigated using luciferase reporter, mobility shift and chromatin immunoprecipitation assays.

KEY RESULTS

Loss of Rev-erb-α or Rev-erb-β reduced the sensitivity of mice to folic acid-induced AKI and eliminated the circadian time dependency in disease severity. This coincided with less extensive ferroptosis, a main cause of folic acid-induced AKI. Moreover, icDKO mice were more resistant to folic acid-induced AKI and ferroptosis as compared with single-gene knockout mice. Supporting this, targeting Rev-erb-α/β by SR8278 attenuated ferroptosis to ameliorate folic acid-induced AKI in mice. Rev-erb-α/β promoted ferroptosis by repressing the transcription of Slc7a11 and HO1 (two ferroptosis-inhibitory genes) via direct binding to a RORE cis-element.

CONCLUSION AND IMPLICATIONS

Targeted inhibition of Rev-erb-α/β limits ferroptosis to ameliorate folic acid-induced AKI in mice. The findings may have implications for improved understanding of circadian clock-controlled ferroptosis and for formulating new strategies to treat AKI.

Survival and renal recovery after acute kidney injury requiring dialysis outside of intensive care units

BACKGROUND

The incidence of acute kidney injury requiring dialysis (AKI-D) is increasing globally and it is usually associated to chronic kidney disease (CKD) and high mortality. Literature is lacking in short- and intermediate-term data on recovery of renal function after acute kidney injury (AKI).

OBJECTIVES

The objective was to evaluate the overall survival and renal recovery after an episode of AKI requiring dialysis out of intensive care units (ICUs).

MATERIALS AND METHODS

Retrospective study including patients admitted in two nephrology units along a period of 2 years. Patients admitted to ICUs and renal transplant patients were excluded. Baseline renal function, mortality and glomerular filtration rate (GFR) improvement were evaluated.

RESULTS

151 consecutive adult patients with AKI requiring renal replacement therapy (RRT) were included. Mean age was 70.5 ± 15.2 years, 60.3% were males. Median baseline creatinine (bCr) and baseline GFR (bGFR) were 1.4 mg/dL and 46 mL/min/1.73 m², respectively. After 1 year of follow-up, we completed the monitoring of 94 patients: 64.9% had died, 10.6% were alive on dialysis and 24.5% were alive without need for RRT. Patients with bGFR > 60 mL/min/1.73 m² prior to AKI episode had a slower but sustained GFR improvement through the follow-up in comparison with patients with bGFR < 60 mL/min/1.73 m² whose recovery was incomplete.

CONCLUSIONS

Patients with AKI requiring RRT have high short- and intermediate-term mortality and some require maintenance dialysis. Patients with GFR > 60 mL/min/1.73 m² prior to AKI had a renal recovery closer to the basal renal function than in patients with a previously diminished GFR.

90 days impacts of remote ischemic preconditioning on patients undergoing open total aortic arch replacement: a post-hoc analysis of previous trial

Background

In the previous randomized controlled trial by our research group, we evaluated the effect of remote ischemic preconditioning (RIPC) in 130 patients (65 per arm) on acute kidney injury (AKI) within 7 days of open total aortic arch replacement. Significantly fewer RIPC-treated patients than sham-treated patients developed postoperative AKI, and, epically, RIPC significantly reduced serious AKI (stage II–III). However, the long-term effect of RIPC in patients undergoing open total aortic arch replacement is unclear.

Methods

This study was a post-hoc analysis. We aimed to assess the roles of RIPC in major adverse kidney events (MAKE), defined as consisting persistent renal dysfunction, renal replacement therapy and mortality, within 90 days after surgery in patients receiving open total aortic arch replacement.

Results

In this 90-day follow-up study, data were available for all study participants. We found that RIPC failed to improve the presence of MAKE within 90 days after surgery (RIPC: 7 of 65[10.8%]) vs sham: 15 of 65[23.1%]; P = 0.061). In those patients who developed AKI after surgery, we found that the rate of MAKE within 90 days after surgery differed between the RIPC group and the sham group (RIPC: 4 of 36[11.2%]; sham: 14 of 48[29.2%]; P = 0.046).

Conclusions

At 90 days after open total aortic arch replacement, we failed to find a difference between the renoprotective effects of RIPC and sham treatment. The effectiveness or ineffectiveness of RIPC should be further investigated in a large randomized sham-controlled trial.

Trial registration

This study was approved by the Ethics Committee of Fuwai Hospital (No. 2016–835) and our previous study was registered at clinicaltrials.gov before patient enrollment (NCT03141385; principal investigator: G.W.; date of registration: March 5, 2017).

Risk of Kidney Injury among Construction Workers Exposed to Heat Stress: A Longitudinal Study from Saudi Arabia

Saudi Arabia (SA) is one of the hottest countries in the world. This study was conducted to assess the impact of summer heat stress in Southeastern SA on short-term kidney injury (KI) among building construction workers and to identify relevant risk factors. Measurements of urinary albumin-creatinine ratio (ACR), height, weight, hydration, symptoms, daily work and behavioral factors were collected in June and September of 2016 from a cohort of construction workers (n = 65) in Al-Ahsa Province, SA. KI was defined as ACR ≥ 30 mg/g. Multivariate linear regression analysis was used to assess factors related to cross-summer changes in ACR. A significant increase in ACR occurred among most workers over the study period; incidence of KI was 18%. Risk factors associated with an increased ACR included dehydration, short sleep, and obesity. The findings suggest that exposure to summer heat may lead to the development of KI among construction workers in this region. Adequate hydration and promotion of healthy habits among workers may help reduce the risk of KI. A reduction in work hours may be the most effective intervention because this action can reduce heat exposure and improve sleep quality.

Evaluation of five different renal recovery definitions for estimation of long-term outcomes of cardiac surgery associated acute kidney injury

Background

The commonly used recommended criteria for renal recovery are not unequivocal. This study compared five different definitions of renal recovery in order to evaluate long-term outcomes of cardiac surgery associated acute kidney injury (CSA-AKI).

Methods

Patients who underwent cardiac surgery between April 2009 and April 2013 were enrolled and divided into acute kidney injury (AKI) and non-AKI groups. The primary endpoint was 3-year major adverse events (MAEs) including death, new dialysis and progressive chronic kidney disease (CKD). We compared five criteria for complete renal recovery: Acute Renal Failure Trial Network (ATN): serum creatinine (SCr) at discharge returned to within baseline SCr + 0.5 mg/dL; Acute Dialysis Quality Initiative (ADQI): returned to within 50% above baseline SCr; Pannu: returned to within 25% above baseline SCr; Kidney Disease: Improving Global Outcomes (KDIGO): eGFR at discharge ≥60 mL/min/1.73 m²; Bucaloiu: returned to ≥90% baseline estimated glomerular filtration rate (eGFR). Multivariate regression analysis was used to compare risk factors for 3-year MAEs.

Results

The rate of complete recovery for ATN, ADQI, Pannu, KDIGO and Bucaloiu were 84.60% (n = 1242), 82.49% (n = 1211), 60.49% (n = 888), 68.60% (n = 1007) and 46.32% (n = 680). After adjusting for confounding factors, AKI with complete renal recovery was a risk factor for 3-year MAEs (OR: 1.69, 95% CI: 1.20–2.38, P <  0.05; OR: 1.45, 95% CI: 1.03–2.04, P <  0.05) according to ATN and ADQI criteria, but not for KDIGO, Pannu and Bucaloiu criteria. We found that relative to patients who recovered to within 0% baseline SCr or recovered to ≥100% baseline eGFR, the threshold values at which significant differences in 3-year MAEs were observed were > 30% or > 0.4 mg/dL above baseline SCr or < 70% of baseline eGFR.

Conclusions

ADQI or ATN-equivalent criteria may overestimate the extent of renal recovery, while KDIGO, Pannu and Bucaloiu equivalent criteria may be more appropriate for clinical use. Our analyses revealed that SCr at discharge > 30% or > 0.4 mg/dL of baseline, or eGFR < 70% of baseline led to significant 3-year MAE incidence differences, which may serve as hints for new definitions of renal recovery.

Routine Adoption of Urinary [IGFBP7]∙[TIMP-2] to Assess Acute Kidney Injury at Any Stage 12 hours After Intensive Care Unit Admission: a Prospective Cohort Study

The urinary tissue inhibitor of metalloproteinases-2 and insulin-like growth factor-binding protein 7 ([TIMP-2]∙[IGFBP7]) have been introduced to improve risk prediction of severe acute kidney injury (AKI) within 12 hours of measurement. We performed a prospective cohort study to evaluate if the predictive value of [TIMP-2]∙[IGFBP7] for AKI might continue after 12 hours. We enrolled 442 critically ill adult patients from June to December 2016. Urine samples were collected at admission for [TIMP-2]∙[IGFBP7] measurement. Baseline patient characteristics were recorded including patients' demographics, prior health history, and the main reason for admission to build a logistic regression model to predict AKI. AKI occurrence differed between patients with [TIMP-2]∙[IGFBP7] ≤0.3 and >0.3 (ng/ml)2/1000 (31.9% and 68.10% respectively; p < 0.001). Patients with AKI had higher biomarker values compared to those without AKI (0.66 (0.21-2.84) vs 0.22 (0.08-0.63) (ng/ml)2/1000; p < 0.001). [TIMP-2]∙[IGFBP7] at ICU admission had a lower performance in predicting AKI at any stage within 48 hours and 7 days after measurement (area under the receiver operating characteristic curve (AUC) equal to 0.70 (95%CI 0.65-0.76), AUC 0.68 (95%CI 0.63-0.73)). In the logistic regression model, 0.1 (ng/ml)2/1000-unit increment was likely to increase the risk of AKI by 2% (p = 0.002).

Renal injury and recovery in pediatric patients after ventricular assist device implantation and cardiac transplant

BACKGROUND

The use of ventricular assist devices (VADs) in children with heart failure may be of particular benefit to those with accompanying renal failure, as improved renal function is seen in some, but not all recipients. We hypothesized that persistent renal dysfunction at 7 days and/or 1 month after VAD implantation would predict chronic kidney disease (CKD) 1 year after heart transplantation (HT).

METHODS

Linkage analysis of all VAD patients enrolled in both the PEDIMACS and PHTS registries between 2012 and 2016. Persistent acute kidney injury (P-AKI), defined as a serum creatinine ≥1.5× baseline, was assessed at post-implant day 7. Estimated glomerular filtration rate (eGFR) was determined at implant, 30 days thereafter, and 12 months post-HT. Pre-implant eGFR, eGFR normalization (to ≥90 mL/min/1.73 m² ), and P-AKI were used to predict post-HT CKD (eGFR <90 mL/min/1.73 m² ).

RESULTS

The mean implant eGFR was 85.4 ± 46.5 mL/min/1.73 m² . P-AKI was present in 19/188 (10%). Mean eGFR at 1 month post-VAD implant was 131.1 ± 62.1 mL/min/1.73 m² , significantly increased above baseline (P < 0.001). At 1 year post-HT (n = 133), 60 (45%) had CKD. Lower pre-implant eGFR was associated with post-HT CKD (OR 0.99, CI: 0.97-0.99, P = 0.005); P-AKI was not (OR 0.96, CI: 0.3-3.0, P = 0.9). Failure to normalize renal function 30 days after implant was highly associated with CKD at 1 year post-transplant (OR 12.5, CI 2.8-55, P = 0.003).

CONCLUSIONS

Renal function improves after VAD implantation. Lower pre-implant eGFR and failure to normalize renal function during the support period are risk factors for CKD development after HT.

Plasma Biomarkers in Predicting Renal Recovery from Acute Kidney Injury in Critically Ill Patients

BACKGROUND

Numerous studies have suggested a possible role for acute kidney injury (AKI) biomarkers in predicting renal recovery both before and after renal replacement therapy (RRT). However, definitions for recovery and whether to include patients dying but free of RRT may influence results.

OBJECTIVES

To validate plasma neutrophil gelatinase-associated lipocalin (pNGAL) as a useful biomarker for predicting or improving the ability of clinical predictors alone to predict recovery following AKI, including in our model plasma B-type natriuretic peptide (pBNP) to account for cardiovascular events.

METHODS

We analyzed 69 patients enrolled in the Acute Renal Failure Trial Network study. pNGAL and pBNP were measured on days 2, 7, and 14. We analyzed their predictive ability for subsequent recovery, defined as alive and independent from dialysis in 60 days. In sensitivity analyses, we explored changes in results with alternative definitions of recovery.

RESULTS

Twenty-nine patients (42%) recovered from AKI. Neither pNGAL nor pBNP, alone or in combination, was accurate predictors of renal recovery-the best area under the receiver-operating characteristics curve (AUC) was for pNGAL using the largest relative change (AUC 0.59, 95% CI 0.45-0.74). The best clinical model achieved superior performance to biomarkers (AUC 0.69, 95% CI 0.56-0.81). The AUC was greatest (0.75, 95% CI 0.60-0.91) when pNGAL + pBNP on day 14 were added to the clinical model but this increase did not achieve statistical significance. However, integrated discrimination improvement analysis showed that the addition of pNGAL and pBNP on day 14 to the clinical model significantly improved the prediction of renal recovery (p = 0.008).

CONCLUSIONS

pNGAL and pBNP can improve the accuracy of clinical parameters in predicting AKI recovery and a full model using biomarkers together with age achieved adequate discrimination.

ICU survival and need of renal replacement therapy with respect to AKI duration in critically ill patients

BACKGROUND

Transient and persistent acute kidney injury (AKI) could share similar physiopathological mechanisms. The objective of our study was to assess prognostic impact of AKI duration on ICU mortality.

DESIGN

Retrospective analysis of a prospective database via cause-specific model, with 28-day ICU mortality as primary end point, considering discharge alive as a competing event and taking into account time-dependent nature of renal recovery. Renal recovery was defined as a decrease of at least one KDIGO class compared to the previous day.

SETTING

23 French ICUs.

PATIENTS

Patients of a French multicentric observational cohort were included if they suffered from AKI at ICU admission between 1996 and 2015.

INTERVENTION

None.

RESULTS

A total of 5242 patients were included. Initial severity according to KDIGO creatinine definition was AKI stage 1 for 2458 patients (46.89%), AKI stage 2 for 1181 (22.53%) and AKI stage 3 for 1603 (30.58%). Crude 28-day ICU mortality according to AKI severity was 22.74% (n = 559), 27.69% (n = 327) and 26.26% (n = 421), respectively. Renal recovery was experienced by 3085 patients (58.85%), and its rate was significantly different between AKI severity stages (P < 0.01). Twenty-eight-day ICU mortality was independently lower in patients experiencing renal recovery [CSHR 0.54 (95% CI 0.46-0.63), P < 0.01]. Lastly, RRT requirement was strongly associated with persistent AKI whichever threshold was chosen between day 2 and 7 to delineate transient from persistent AKI.

CONCLUSIONS

Short-term renal recovery, according to several definitions, was independently associated with higher mortality and RRT requirement. Moreover, distinction between transient and persistent AKI is consequently a clinically relevant surrogate outcome variable for diagnostic testing in critically ill patients.

Long-term survival in patients with septic acute kidney injury is strongly influenced by renal recovery

BACKGROUND

Several studies have shown that long-term survival after acute kidney injury (AKI) is reduced even if there is clinical recovery. However, we recently reported that in septic shock patients those that recover from AKI have survival similar to patients without AKI. Here, we studied a cohort with less severe sepsis to examine the effects of AKI on longer-term survival as a function of recovery by discharge.

METHODS

We analyzed patients with community-acquired pneumonia from the Genetic and Inflammatory Markers of Sepsis (GenIMS) cohort. We included patients who developed AKI (KDIGO stages 2-3) and defined renal recovery as alive at hospital discharge with return of SCr to within 150% of baseline without dialysis. Our primary outcome was survival up to 3 years analyzed using Gray's model.

RESULTS

Of the 1742 patients who survived to hospital discharge, stage 2-3 AKI occurred in 262 (15%), of which 111 (42.4%) recovered. Compared to recovered patients, patients without recovery were older (75 ±14 vs 69 ±15 years, p<0.001) and were more likely to have at least stage 1 AKI on day 1 (83% vs 52%, p<0.001). Overall, 445 patients (25.5%) died during follow-up, 23.4% (347/1480) for no AKI, 28% (31/111) for AKI with recovery and 44.3% (67/151) for AKI without recovery. Patients who did not recover had worse survival compared to no AKI (HR range 1.05-2.46, p = 0.01), while recovering patients had similar survival compared to no AKI (HR 1.01, 95%CI 0.69-1.47, p = 0.96). Absence of AKI on day 1, no in-hospital renal replacement therapy (RRT), higher Apache III score and higher baseline SCr were associated with recovery after AKI.

CONCLUSIONS

In patients with sepsis, recovery by hospital discharge is associated with long-term survival similar to patients without AKI.

Extended Mortality and Chronic Kidney Disease After Septic Acute Kidney Injury

PURPOSE

To evaluate 1-year mortality in patients with septic acute kidney injury (AKI) and to determine association between initial AKI recovery patterns (reversal within 5 days, beyond 5 days but recovery, or nonrecovery) and chronic kidney disease (CKD) progression.

METHODS

Prospective observational study, with retrospective evaluation of initial nonconsenters, of critically ill patients with septic AKI.

RESULTS

We studied 207 patients (age, mean [SD]: 64 [16] years, 39% males), of which 56 (27%), 18 (9%), and 9 (4%) died in intensive care unit (ICU), post-ICU in hospital, and posthospitalization, respectively. Infections (including pneumonia) and major adverse cardiac events accounted for 64% and 12% of deaths, respectively. Factors independently associated with 1-year mortality include older age, ischemic heart disease, higher Simplified Acute Physiology Score II, central nervous system or musculoskeletal primary infections, higher daily fluid balance (FB), and frusemide administration during ICU stay (all P < .05). Among 63 patients receiving renal replacement therapy (RRT), hospital mortality was higher with cumulative median FB >8 L versus ≤8 L at RRT initiation (57% vs 24%; P = .009); there was trend for less ICU- and RRT-free days at day 28 in patients with higher FB pre-RRT (P = NS). Chronic kidney disease progression over 1 year developed in 21%, 30%, and 79% of 105 initial survivors with AKI reversal, recovery, and nonrecovery, respectively (P < .001). Acute kidney injury nonrecovery during hospitalization independently predicted CKD progression (P = .001).

CONCLUSIONS

Patients with septic AKI had 40% 1-year mortality, mainly associated with infections. High FB and frusemide administration were modifiable risk factors. Risk of CKD progression is high especially with initial AKI nonrecovery.

Long-Term Clinical Outcomes after Early Initiation of RRT in Critically Ill Patients with AKI

Whether earlier initiation of RRT in critically ill patients with AKI can improve outcomes remains debated. We examined follow-up data from a large clinical trial to prospectively investigate the long-term outcomes associated with the timing of RRT initiation in such patients. We extended the follow-up of patients in the Early Versus Delayed Initiation of RRT in Critically Ill Patients with AKI (ELAIN) Trial from 90 days to 1 year after randomization for 230 (99.6%) patients. The primary outcome was a composite of major adverse kidney events (persistent renal dysfunction, dialysis dependence, and mortality) at 1 year. Secondary outcomes included inflammatory markers. Overall, 72 of 111 (64.9%) and 106 of 119 (89.1%) patients met the primary outcome in the early (stage 2 AKI) and delayed (stage 3 AKI) initiation groups, respectively (odds ratio [OR] with early initiation, 0.23; 95% confidence interval [95% CI], 0.11 to 0.45; P< 0.001). The early initiation group had a 1-year all-cause mortality rate (56 of 111 [50.2%]) significantly lower than that of the delayed initiation group (83 of 119 [69.8%]; absolute difference, -19.6%; 95% CI, -32.0% to -7.2%; P<0.01). After 1 year, 16 of 55 (29.1%) and 23 of 36 (63.9%) surviving patients in the early and delayed groups, respectively, failed to recover renal function (absolute difference, -34.8%; 95% CI, -54.6% to -15.0%; P=0.001). In conclusion, early initiation of RRT in these critically ill patients with AKI significantly reduced the occurrence of major adverse kidney events, reduced mortality, and enhanced renal recovery at 1 year.

Derivation and External Validation of Prediction Models for Advanced Chronic Kidney Disease Following Acute Kidney Injury

IMPORTANCE

Some patients will develop chronic kidney disease after a hospitalization with acute kidney injury; however, no risk-prediction tools have been developed to identify high-risk patients requiring follow-up.

OBJECTIVE

To derive and validate predictive models for progression of acute kidney injury to advanced chronic kidney disease.

DESIGN, SETTING, AND PARTICIPANTS

Data from 2 population-based cohorts of patients with a prehospitalization estimated glomerular filtration rate (eGFR) of more than 45 mL/min/1.73 m2 and who had survived hospitalization with acute kidney injury (defined by a serum creatinine increase during hospitalization > 0.3 mg/dL or > 50% of their prehospitalization baseline), were used to derive and validate multivariable prediction models. The risk models were derived from 9973 patients hospitalized in Alberta, Canada (April 2004-March 2014, with follow-up to March 2015). The risk models were externally validated with data from a cohort of 2761 patients hospitalized in Ontario, Canada (June 2004-March 2012, with follow-up to March 2013).

EXPOSURES

Demographic, laboratory, and comorbidity variables measured prior to discharge.

MAIN OUTCOMES AND MEASURES

Advanced chronic kidney disease was defined by a sustained reduction in eGFR less than 30 mL/min/1.73 m2 for at least 3 months during the year after discharge. All participants were followed up for up to 1 year.

RESULTS

The participants (mean [SD] age, 66 [15] years in the derivation and internal validation cohorts and 69 [11] years in the external validation cohort; 40%-43% women per cohort) had a mean (SD) baseline serum creatinine level of 1.0 (0.2) mg/dL and more than 20% had stage 2 or 3 acute kidney injury. Advanced chronic kidney disease developed in 408 (2.7%) of 9973 patients in the derivation cohort and 62 (2.2%) of 2761 patients in the external validation cohort. In the derivation cohort, 6 variables were independently associated with the outcome: older age, female sex, higher baseline serum creatinine value, albuminuria, greater severity of acute kidney injury, and higher serum creatinine value at discharge. In the external validation cohort, a multivariable model including these 6 variables had a C statistic of 0.81 (95% CI, 0.75-0.86) and improved discrimination and reclassification compared with reduced models that included age, sex, and discharge serum creatinine value alone (integrated discrimination improvement, 2.6%; 95% CI, 1.1%-4.0%; categorical net reclassification index, 13.5%; 95% CI, 1.9%-25.1%) or included age, sex, and acute kidney injury stage alone (integrated discrimination improvement, 8.0%; 95% CI, 5.1%-11.0%; categorical net reclassification index, 79.9%; 95% CI, 60.9%-98.9%).

CONCLUSIONS AND RELEVANCE

A multivariable model using routine laboratory data was able to predict advanced chronic kidney disease following hospitalization with acute kidney injury. The utility of this model in clinical care requires further research.

Points of Concern in Post Acute Kidney Injury Management

The incidence of acute kidney injury (AKI) will in the future remain high, partly due to an increase in comorbidities and other AKI favoring factors such as the rise in high-risk diagnostic and therapeutic interventions. AKI has emerged as a major public health concern with high human and financial costs. It has recently been demonstrated that patients surviving an AKI episode show increased all-cause mortality, chronic kidney disease (CKD), ESRD, cardiovascular events, and reduced quality of life. Although it is important to acknowledge that, after an AKI episode, the risk of dying by far exceeds the risk of developing incident or progressive CKD and/or entering a maintenance renal replacement therapy (RRT) program, currently only a minority of patients are referred for renal follow-up, even after AKI-requiring RRT. On the other hand, renal follow-up for all AKI survivors might not be necessary and would represent an overwhelming work load for the health care system. There are at present no clear guidelines on which patients should be referred and on the elements of post AKI care that may improve non-renal and renal outcomes. In this review, we discuss several points of concern in post-AKI management and propose an algorithm on post-AKI care, mainly based on the renal recovery pattern at discharge from the hospital. Potential opportunities to improve care include appropriate risk stratification, close monitoring of kidney function, management of CKD complications, blood pressure control, medication reconciliation, and education of patients and non-nephrologists on AKI and its downstream complications.

Post-discharge kidney function is associated with subsequent ten-year renal progression risk among survivors of acute kidney injury

The extent to which renal progression after acute kidney injury (AKI) arises from an initial step drop in kidney function (incomplete recovery), or from a long-term trajectory of subsequent decline, is unclear. This makes it challenging to plan or time post-discharge follow-up. This study of 14651 hospital survivors in 2003 (1966 with AKI, 12685 no AKI) separates incomplete recovery from subsequent renal decline by using the post-discharge estimated glomerular filtration rate (eGFR) rather than the pre-admission as a new reference point for determining subsequent renal outcomes. Outcomes were sustained 30% renal decline and de novo CKD stage 4, followed from 2003-2013. Death was a competing risk. Overall, death was more common than subsequent renal decline (37.5% vs 11.3%) and CKD stage 4 (4.5%). Overall, 25.7% of AKI patients had non-recovery. Subsequent renal decline was greater after AKI (vs no AKI) (14.8% vs 10.8%). Renal decline after AKI (vs no AKI) was greatest among those with higher post-discharge eGFRs with multivariable hazard ratios of 2.29 (1.88-2.78); 1.50 (1.13-2.00); 0.94 (0.68-1.32) and 0.95 (0.64-1.41) at eGFRs of 60 or more; 45-59; 30-44 and under 30, respectively. The excess risk after AKI persisted over ten years of study, irrespective of AKI severity, or post-episode proteinuria. Thus, even if post-discharge kidney function returns to normal, hospital admission with AKI is associated with increased renal progression that persists for up to ten years. Follow-up plans should avoid false reassurance when eGFR after AKI returns to normal.

Recovery after Acute Kidney Injury

RATIONALE

Little is known about how acute kidney injury (AKI) resolves, and whether patterns of reversal of renal dysfunction differ among patients with respect to ultimate recovery.

OBJECTIVES

We sought to examine different patterns for AKI reversal that are found in patients and assess how they relate to postdischarge outcomes.

METHODS

We studied 16,968 critically ill patients with Kidney Disease Improving Global Outcomes stage 2 or 3 AKI, using an electronic database. Reversal of AKI was defined as alive and no longer meeting criteria for even stage 1. Recovery was defined as reversal at hospital discharge.

MEASUREMENTS AND MAIN RESULTS

We observed five patterns. The most common (4,508; 26.6%) was early reversal that was sustained through discharge, but almost as many patients (4,496; 26.5%) had no reversal at all. The remaining patients had late reversal after Day 7 (9.7%); early reversal with one or more relapses, but with ultimate recovery (22.5%); and relapsing without recovery (14.7%). Outcomes for patients with these phenotypes were quite different, with age-adjusted 1-year survival varying from more than 90% for early reversal to less than 40% for patients never reversing. Relapses are common (37.3%), especially in the first 72 hours after reversal, and are associated with a fivefold increased risk for death by 1 year compared with early sustained reversal.

CONCLUSIONS

We have identified five distinct recovery phenotypes on the basis of the clinical course over the first week after AKI manifestation. These phenotypes may identify patients amenable to therapeutic intervention. Long-term outcomes are associated with recovery status at hospital discharge.

Renal recovery after severe acute kidney injury in critically ill myeloma patients: a retrospective study

Background

Despite substantial improvements in the management of multiple myeloma, renal failure remains an important burden that tremendously impairs prognosis. The purpose of this study was to describe the characteristics and to establish prognostic factors of renal recovery in myeloma patients admitted to the intensive care unit (ICU) for acute kidney injury (AKI) Stage 3 treated with renal replacement therapy (RRT).

Methods

A retrospective single-centre cohort study was performed, including consecutive myeloma patients admitted to one medical ICU between 1 January 2007 and 1 September 2015 and treated with RRT. Patients were evaluated 60 days after initiation of RRT and divided into three groups: alive without dialysis, alive and dialysis-dependent or deceased. A univariate analysis was performed to identify factors associated with renal recovery (alive without dialysis 60 days after initiation of RRT).

Results

Fifty patients were included in the study. Mean age was 63 (interquartile range: 58–70) years and 32 (64%) were male. Patients were admitted to the ICU 4 (1–7) years after the diagnosis of myeloma. Twenty-one (42%) had already been treated with high-dose therapy combined with autologous stem cell transplantation. Baseline renal function evaluated by estimated glomerular filtration rate (GFR) before ICU admission was 63 (44–90) mL/min/1.73 m². The mean SOFA score at Day 1 was 7 (4–8). The three main reasons for ICU admission were AKI (n = 31, 62%), acute pulmonary oedema (n = 17, 32%) and sepsis (n = 10, 20%). During ICU stay, RRT was implemented in all patients, 16 (32%) patients required invasive mechanical ventilation and 12 (24%) received vasopressors. The mean ICU and hospital length of stay were 6 (1–7) and 28 (13–34) days, respectively. At Day 60, 23 (46%) patients were alive without dialysis, 17 (32%) had died and 10 (20%) were still undergoing dialysis. Among the 23 patients who recovered, the mean duration of dialysis was 6 (2–18) days and renal function was not significantly different from baseline [estimated GFR at baseline = 65 (25–74) mL/min/1.73 m² versus 63 (56–70) mL/min/1.73 m² at Day 60, P = 0.70]. By univariate analysis, two factors were associated with nonrecovery of renal function at Day 60: a history of high-dose therapy combined with autologous stem cell transplantation [odds ratio (OR) = 6.1, 95% confidence interval (CI) 1.7–21.6; P = 0.008] and a proteinuria at ICU admission >370 mg/mmol creatinine (OR = 4.2, 95% CI 1.1–17; P = 0.02). None of the other variables related to the haematological malignancy or to the ICU stay was associated with renal recovery at Day 60.

Conclusions

AKI Stage 3 in critically ill myeloma patients was associated with a lower than expected hospital mortality. Patients with a high level of proteinuria and a history of high-dose therapy combined with autologous stem cell transplantation were less likely to recover their renal function at Day 60.

Key words

dialysis, intensive care, multiple myeloma, prognosis, proteinuria

Association between recurrence of acute kidney injury and mortality in intensive care unit patients with severe sepsis

Background

Acute kidney injury (AKI) occurs in more than half critically ill patients admitted in intensive care units (ICU) and increases the mortality risk. The main cause of AKI in ICU is sepsis. AKI severity and other related variables such as recurrence of AKI episodes may influence mortality risk. While AKI recurrence after hospital discharge has been recently related to an increased risk of mortality, little is known about the rate and consequences of AKI recurrence during the ICU stay. Our hypothesis is that AKI recurrence during ICU stay in septic patients may be associated to a higher mortality risk.

Methods

We prospectively enrolled all (405) adult patients admitted to the ICU of our hospital with the diagnosis of severe sepsis/septic shock for a period of 30 months. Serum creatinine was measured daily. ‘In-ICU AKI recurrence’ was defined as a new spontaneous rise of ≥0.3 mg/dl within 48 h from the lowest serum creatinine after the previous AKI episode.

Results

Excluding 5 patients who suffered the AKI after the initial admission to ICU, 331 patients out of the 400 patients (82.8%) developed at least one AKI while they remained in the ICU. Among them, 79 (19.8%) developed ≥2 AKI episodes.

Excluding 69 patients without AKI, in-hospital (adjusted HR = 2.48, 95% CI 1.47–4.19), 90-day (adjusted HR = 2.54, 95% CI 1.55–4.16) and end of follow-up (adjusted HR = 1.97, 95% CI 1.36–2.84) mortality rates were significantly higher in patients with recurrent AKI, independently of sex, age, mechanical ventilation necessity, APACHE score, baseline estimated glomerular filtration rate, complete recovery and KDIGO stage.

Conclusions

AKI recurred in about 20% of ICU patients after a first episode of sepsis-related AKI. This recurrence increases the mortality rate independently of sepsis severity and of the KDIGO stage of the initial AKI episode. ICU physicians must be aware of the risks related to AKI recurrence while multiple episodes of AKI should be highlighted in electronic medical records and included in the variables of clinical risk scores.

Acute kidney injury in the ICU: from injury to recovery: reports from the 5th Paris International Conference

The French Intensive Care Society organized its yearly Paris International Conference in intensive care on June 18-19, 2015. The main purpose of this meeting is to gather the best experts in the field in order to provide the highest quality update on a chosen topic. In 2015, the selected theme was: "Acute Renal Failure in the ICU: from injury to recovery." The conference program covered multiple aspects of renal failure, including epidemiology, diagnosis, treatment and kidney support system, prognosis and recovery together with acute renal failure in specific settings. The present report provides a summary of every presentation including the key message and references and is structured in eight sections: (a) diagnosis and evaluation, (b) old and new diagnosis tools,

Acute kidney injury in the ICU: from injury to recovery: reports from the 5th Paris International Conference

The French Intensive Care Society organized its yearly Paris International Conference in intensive care on June 18-19, 2015. The main purpose of this meeting is to gather the best experts in the field in order to provide the highest quality update on a chosen topic. In 2015, the selected theme was: "Acute Renal Failure in the ICU: from injury to recovery." The conference program covered multiple aspects of renal failure, including epidemiology, diagnosis, treatment and kidney support system, prognosis and recovery together with acute renal failure in specific settings. The present report provides a summary of every presentation including the key message and references and is structured in eight sections: (a) diagnosis and evaluation, (b) old and new diagnosis tools,

Long-term Effects of Remote Ischemic Preconditioning on Kidney Function in High-risk Cardiac Surgery Patients

Background

In a multicenter, randomized trial, the authors enrolled patients at high-risk for acute kidney injury as identified by a Cleveland Clinic Foundation score of 6 or more. The authors enrolled 240 patients at four hospitals and randomized them to remote ischemic preconditioning or control. The authors found that remote ischemic preconditioning reduced acute kidney injury in high-risk patients undergoing cardiac surgery. The authors now report on the effects of remote ischemic preconditioning on 90-day outcomes.

Methods

In this follow-up study of the RenalRIP trial, the authors examined the effect of remote ischemic preconditioning on the composite endpoint major adverse kidney events consisting of mortality, need for renal replacement therapy, and persistent renal dysfunction at 90 days. Secondary outcomes were persistent renal dysfunction and dialysis dependence in patients with acute kidney injury.

Results

Remote ischemic preconditioning significantly reduced the occurrence of major adverse kidney events at 90 days (17 of 120 [14.2%]) versus control (30 of 120 [25.0%]; absolute risk reduction, 10.8%; 95% CI, 0.9 to 20.8%; P = 0.034). In those patients who developed acute kidney injury after cardiac surgery, 2 of 38 subjects in the remote ischemic preconditioning group (5.3%) and 13 of 56 subjects in the control group (23.2%) failed to recover renal function at 90 days (absolute risk reduction, 17.9%; 95% CI, 4.8 to 31.1%; P = 0.020). Acute kidney injury biomarkers were also increased in patients reaching the major adverse kidney event endpoint compared to patients who did not.

Conclusions

Remote ischemic preconditioning significantly reduced the 3-month incidence of a composite endpoint major adverse kidney events consisting of mortality, need for renal replacement therapy, and persistent renal dysfunction in high-risk patients undergoing cardiac surgery. Furthermore, remote ischemic preconditioning enhanced renal recovery in patients with acute kidney injury.

The future of critical care: renal support in 2027

Since its inception four decades ago, both the clinical and technologic aspects of continuous renal replacement therapy (CRRT) have evolved substantially. Devices now specifically designed for critically ill patients with acute kidney injury are widely available and the clinical challenges associated with treating this complex patient population continue to be addressed. However, several important questions remain unanswered, leaving doubts in the minds of many clinicians about therapy prescription/delivery and patient management. Specifically, questions surrounding therapy dosing, timing of initiation and termination, fluid management, anticoagulation, drug dosing, and data analytics may lead to inconsistent delivery of CRRT and even reluctance to prescribe it. In this review, we discuss current limitations of CRRT and potential solutions over the next decade from both a patient management and a technology perspective. We also address the issue of sustainability for CRRT and related therapies beyond 2027 and raise several points for consideration.

Long-term outcome in ICU patients with acute kidney injury treated with renal replacement therapy: a prospective cohort study

Background

In intensive care unit (ICU) patients, acute kidney injury treated with renal replacement therapy (AKI-RRT) is associated with adverse outcomes. The aim of this study was to evaluate variables associated with long-term survival and kidney outcome and to assess the composite endpoint major adverse kidney events (MAKE; defined as death, incomplete kidney recovery, or development of end-stage renal disease treated with RRT) in a cohort of ICU patients with AKI-RRT.

Methods

We conducted a single-center, prospective observational study in a 50-bed ICU tertiary care hospital. During the study period from August 2004 through December 2012, all consecutive adult patients with AKI-RRT were included. Data were prospectively recorded during the patients’ hospital stay and were retrieved from the hospital databases. Data on long-term follow-up were gathered during follow-up consultation or, in the absence of this, by consulting the general physician.

Results

AKI-RRT was reported in 1292 of 23,665 first ICU admissions (5.5 %). Mortality increased from 59.7 % at hospital discharge to 72.1 % at 3 years. A Cox proportional hazards model demonstrated an association of increasing age, severity of illness, and continuous RRT with long-term mortality. Among hospital survivors with reference creatinine measurements, 1-year renal recovery was complete in 48.4 % and incomplete in 32.6 %. Dialysis dependence was reported in 19.0 % and was associated with age, diabetes, chronic kidney disease (CKD), and oliguria at the time of initiation of RRT. MAKE increased from 83.1 % at hospital discharge to 93.7 % at 3 years. Multivariate regression analysis showed no association of classical determinants of outcome (preexisting CKD, timing of initiation of RRT, and RRT modality) with MAKE at 1 year.

Conclusions

Our study demonstrates poor long-term survival after AKI-RRT that was determined mainly by severity of illness and RRT modality at initiation of RRT. Renal recovery is limited, especially in patients with acute-on-chronic kidney disease, making nephrological follow-up imperative. MAKE is associated mainly with variables determining mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1409-z) contains supplementary material, which is available to authorized users.

The Effects of Alternative Resuscitation Strategies on Acute Kidney Injury in Patients with Septic Shock

RATIONALE

Septic shock is a common cause of acute kidney injury (AKI), and fluid resuscitation is a major part of therapy.

OBJECTIVES

To determine if structured resuscitation designed to alter fluid, blood, and vasopressor use affects the development or severity of AKI or outcomes.

METHODS

Ancillary study to the ProCESS (Protocolized Care for Early Septic Shock) trial of alternative resuscitation strategies (two protocols vs. usual care) for septic shock.

MEASUREMENTS AND MAIN RESULTS

We studied 1,243 patients and classified AKI using serum creatinine and urine output. We determined recovery status at hospital discharge, examined rates of renal replacement therapy and fluid overload, and measured biomarkers of kidney damage. Among patients without evidence of AKI at enrollment, 37.6% of protocolized care and 38.1% of usual care patients developed kidney injury (P = 0.90). AKI duration (P = 0.59) and rates of renal replacement therapy did not differ between study arms (6.9% for protocolized care and 4.3% for usual care; P = 0.08). Fluid overload occurred in 8.3% of protocolized care and 6.3% of usual care patients (P = 0.26). Among patients with severe AKI, complete and partial recovery was 50.7 and 13.2% for protocolized patients and 49.1 and 13.4% for usual care patients (P = 0.93). Sixty-day hospital mortality was 6.2% for patients without AKI, 16.8% for those with stage 1, and 27.7% for stages 2 to 3.

CONCLUSIONS

In patients with septic shock, AKI is common and associated with adverse outcomes, but it is not influenced by protocolized resuscitation compared with usual care.

Establishing a continuum of acute kidney injury - tracing AKI using data source linkage and long-term follow-up: Workgroup Statements from the 15th ADQI Consensus Conference

Background

Acute kidney injury (AKI) is independently associated with the development of chronic kidney disease, endstage kidney disease and increased all-cause and cardiovascular-specific mortality. The severity of the renal insult and the development of multiple AKI episodes increase the risk of occurrence of these outcomes. Despite these long-term effects, only a minority of patients receive nephrologist follow up after an episode of AKI; those that do may have improved outcomes. Furthermore, relatively simple quality improvement strategies have the potential to change this status quo.

Methods

On this background, a working group of the 15^th Acute Dialysis Quality Initiative (ADQI) conference applied the consensus-building process informed by review of English language articles identified through PubMed search to address questions related to the opportunities, methodological requirements and barriers for longitudinal follow-up of patients with AKI in the era of electronic health records and Big Data.

Results

Four consensus statements answering the key questions identified by the working group are developed.

Conclusions

We have identified minimal data elements and potential data sources necessary to trace the natural history of patients from onset of AKI to long-term outcome. Minimum infrastructure and key barriers to achieving these goals are outlined together with proposed solutions.

Impact and Progression of Organ Dysfunction in Patients with Necrotizing Soft Tissue Infections: A Multicenter Study

BACKGROUND

Necrotizing soft tissue infections (NSTI) represent a rare but devastating disease for which the systemic manifestations have been poorly characterized. In an effort to define an optimal endpoint for clinical trials in this condition, the objective of this study was to establish the pattern of organ dysfunction over time and determine the correlation between organ dysfunction and clinical outcome in patients with NSTI.

METHODS

We conducted a multicenter, retrospective clinical study of patients with NSTI presenting to 12 academic medical centers in the U.S. during 2013. Patients with a diagnosis of NSTI confirmed by surgical findings were included. Organ dysfunction was assessed using a modified Sequential Organ Failure Assessment (SOFA) score (mSOFA: excluding liver) on admission and on hospital days 1, 2, 3, 7, 10, and 14. The presence of organ dysfunction on admission and resolution of organ dysfunction were correlated with clinical parameters, including intensive care unit (ICU)-free days (of 28 d), ventilator-free days, number of debridements, and mortality rate. The incidence of acute kidney injury (AKI) and recovery also were assessed.

RESULTS

There were 198 patients enrolled, of whom 62% were male, the mean age was 51 years, and 40% had monomicrobial infections. The mean mSOFA score on admission was 2.4 ± 3.0, with 49% of the patients having a score ≥2 and 35% a score of ≥3. Patients typically demonstrated worsening of the mSOFA score over the first 24 h followed by gradual resolution. An mSOFA ≥3 at admission was associated with a significant decrease in ventilator-free days (mean 20.1 vs. 25.6 days; p < 0.001); ICU-free days (15.2 vs. 23.1, p < 0.001); more debridements (mean 2.3 vs. 2.0; p = 0.11); a higher mortality rate (15.9% vs. 3.1%; p = 0.003); and a higher rate of AKI (59.4 vs. 35.9%; p < 0.001). The persistence of organ dysfunction (mSOFA >1) among survivors at day 14 was associated with fewer ICU-free days (17.8 vs. 23.6; p < 0.001) and ventilator-free days (23.6 vs. 27; p = 0.001) and a lower recovery rate from AKI (38.7% vs. 81.3%; p < 0.001).

CONCLUSION

Early development of systemic organ dysfunction in patients with NSTI is associated with higher morbidity and mortality rates. Failure of the resolution of organ dysfunction by day 14 forecasts a poor outcome. The mSOFA score may be a useful marker for patient selection for inclusion in interventional trials, and the resolution of organ dysfunction by day 14 may be an important clinical endpoint.

Recovery from AKI in the critically ill: potential confounders in the evaluation

PURPOSE

Studies on recovery from acute kidney injury (AKI) in ICU patients yield variable results. We assessed the impact of different recovery definitions, of different exclusion criteria, and of imputing missing baseline creatinine on AKI recovery in a heterogeneous ICU population.

METHODS

Secondary analysis of the EPaNIC database. Recovery of kidney function in patients who developed AKI in ICU was assessed at hospital discharge. We studied recovery rates of different AKI stages with different definitions of recovery after inclusion or exclusion of non-survivors and in patients with or without chronic kidney disease (CKD). In addition, the impact of imputing missing baseline creatinine was investigated.

RESULTS

A total of 1310 AKI patients were studied of which 977 were discharged alive from hospital. Rate of complete recovery (absence of KDIGO criteria) was markedly higher in survivors than in all AKI patients (79.5 vs 67.0%), especially for more severe forms of AKI. For patients with CKD, only the need for renal replacement therapy worsened kidney outcome as compared with no-CKD patients. Using stricter definitions of complete recovery significantly reduced its occurrence. New or worsening CKD occurred in 30% of AKI survivors. In no-CKD patients with available baseline creatinine, using an imputed baseline did not affect recovery. Patients with unavailable baseline creatinine were different from those with known baseline and revealed different recovery patterns.

CONCLUSION

These results indicate the need for rigorous description of AKI severity, the included population, definitions, and baseline creatinine handling in reports on AKI recovery.

Pediatric continuous renal replacement: 20 years later

INTRODUCTION

More than 20 years have passed since the first clinical application of continuous renal replacement therapy (CRRT) in children. In that revolutionary era, before roller pumps and dialysis monitors for intensive care units were readily available, continuous arteriovenous hemofiltration was the most common treatment for critically ill children.

MAJOR FINDINGS

Those steps were the basis for current knowledge about modern CRRT. Research on circuit rheology and filter materials allowed for the improvement of materials, and the optimization of patency and session life spans. Hemofiltration was coupled with dialysis to increase dialytic dose and system efficiency. Several systems were required to optimize ultrafiltration and manage fluid overload. A quarter of a century later, another revolution is taking place. Acute renal failure has been recognized as a threatening syndrome, independently associated with mortality in critically ill children and characterized by a broad spectrum of clinical phenotypes. For this reason, it has been redefined as acute kidney injury (AKI). This condition is today accurately classified in both adults and children, and has been identified as a primary condition for prevention and aggressive treatment in all pediatric intensive care unit patients. Critically ill neonates and children with multiple organ dysfunction are certainly at higher risk of AKI. Finally, novel technology specifically dedicated to pediatric patients allows feasible and easy application of CRRT to infants and children: a new field of critical care nephrology, dedicated to pediatric patients, has been fully developed.

CONCLUSION

After 20 years, significant developments in critical care nephrology have taken place. Clinical and technical issues have both been addressed, and severe pediatric AKI can currently be managed with accurate and safe dialysis machines that will likely warrant outcome improvements over the following decade.