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Background: There are no consensus definitions for evaluating kidney function recovery after acute kidney injury (AKI) and acute kidney disease (AKD), nor is it clear how recovery varies across populations and clinical subsets. We present a federated analysis of four population-based cohorts from Canada, Denmark and Scotland, 2011-18., Methods: We identified incident AKD defined by serum creatinine changes within 48 h, 7 days and 90 days based on KDIGO AKI and AKD criteria. Separately, we applied changes up to 365 days to address widely used e-alert implementations that extend beyond the KDIGO AKI and AKD timeframes. Kidney recovery was based on resolution of AKD and a subsequent creatinine measurement below 1.2× baseline. We evaluated transitions between non-recovery, recovery and death up to 1 year; within age, sex and comorbidity subgroups; between subset AKD definitions; and across cohorts., Results: There were 464 868 incident cases, median age 67-75 years. At 1 year, results were consistent across cohorts, with pooled mortalities for creatinine changes within 48 h, 7 days, 90 days and 365 days (and 95% confidence interval) of 40% (34%-45%), 40% (34%-46%), 37% (31%-42%) and 22% (16%-29%) respectively, and non-recovery of kidney function of 19% (15%-23%), 30% (24%-35%), 25% (21%-29%) and 37% (30%-43%), respectively. Recovery by 14 and 90 days was frequently not sustained at 1 year. Older males and those with heart failure or cancer were more likely to die than to experience sustained non-recovery, whereas the converse was true for younger females and those with diabetes., Conclusion: Consistently across multiple cohorts, based on 1-year mortality and non-recovery, KDIGO AKD (up to 90 days) is at least prognostically similar to KDIGO AKI (7 days), and covers more people. Outcomes associated with AKD vary by age, sex and comorbidities such that older males are more likely to die, and younger females are less likely to recover., (© The Author(s) 2023. Published by Oxford University Press on behalf of the ERA.)

Rationale & Objective: Survivors of acute kidney injury (AKI) are at high risk of adverse outcomes. Monitoring of kidney function, screening for proteinuria, use of statins and renin-angiotensin-aldosterone system (RAAS) inhibitors, and nephrology follow-up among survivors have not been fully characterized. We examined these processes of care after discharge in survivors of hospitalized AKI., Study Design: Population-based retrospective cohort study., Setting & Participants: Adults in Alberta, Canada, admitted to the hospital between 2009 and 2017, then followed from their discharge date until 2019 for a median follow-up of 2.7 years., Exposure: Hospital-acquired AKI diagnostically conforming to Kidney Disease: Improving Global Outcomes (KDIGO) serum creatinine criteria for stage 2 or stage 3 disease, or the need for acute dialysis., Outcome: Outcomes after hospital discharge included the proportion of participants who had evaluation of kidney function, were seen by a specialist or general practitioner, and received postdischarge prescriptions for recommended medications for chronic kidney disease (CKD)., Analytical Approach: Cumulative incidence curves to characterize the proportion of participants who received each process of care outcome within the first 90 days and subsequent 1-year follow-up period after hospital discharge. To avoid risks associated with multiple hypothesis testing, differences were not statistically compared across groups., Results: The cohort (n=23,921) included 50.2% men (n=12,015) with a median age of 68.1 [IQR, 56.9-78.8] years. Within 90 days after discharge, 21.2% and 8.6% of patients with and without pre-existing CKD, respectively, were seen by a nephrologist; 60.1% of AKI survivors had at least 1 serum creatinine measured, but only 25.5% had an assessment for albuminuria within 90 days after discharge; 52.7% of AKI survivors with pre-existing CKD, and 51.6% with de novo CKD were prescribed a RAAS inhibitor within 4-15 months after discharge., Limitations: Retrospective data were collected as part of routine clinical care., Conclusions: The proportion of patients receiving optimal care after an episode of AKI in Alberta was low and may represent a target for improving long-term outcomes for this population., Plain-Language Summary: A study in Alberta, Canada, examined the care received by patients with acute kidney disease (AKI) during hospitalization and after discharge between 2007 and 2019. The results showed that a low proportion of patients with moderate to severe AKI were seen by a kidney specialist during hospitalization or within 90 days after discharge. Fewer than 25% of AKI patients had their kidney function monitored with both blood and urine tests within 90 days of discharge. Additionally, about half of AKI survivors with chronic kidney disease (CKD) were prescribed guideline recommended medications for CKD within 15 months after discharge. There is potential to improve health care delivery to these patients both in hospital and after hospital discharge., (Copyright © 2023 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background Patients with chronic kidney disease (CKD) can experience acute coronary syndromes (ACS) with high morbidity and mortality. Early invasive management of ACS is recommended for most high-risk patients; however, choosing between an early invasive versus conservative management approach may be influenced by the unique risk of kidney failure for patients with CKD. Methods and Results This discrete choice experiment measured the preferences of patients with CKD for future cardiovascular events versus acute kidney injury and kidney failure following invasive heart procedures for ACS. The discrete choice experiment, consisting of 8 choice tasks, was administered to adult patients attending 2 CKD clinics in Calgary, Alberta. The part-worth utilities of each attribute were determined using multinomial logit models, and preference heterogeneity was explored using latent class analysis. A total of 140 patients completed the discrete choice experiment. The mean age of patients was 64 years, 52% were male, and mean estimated glomerular filtration rate was 37 mL/min per 1.73 m 2 . Across the range of levels, risk of mortality was the most important attribute, followed by risk of end-stage kidney disease and risk of recurrent myocardial infarction. Latent class analysis identified 2 distinct preference groups. The largest group included 115 (83%) patients, who placed the greatest value on treatment benefits and expressed the strongest preference for reducing mortality. A second group of 25 (17%) patients was identified who were procedure averse and had a strong preference toward conservative management of ACS and avoiding acute kidney injury requiring dialysis. Conclusions The preferences of most patients with CKD for management of ACS were most influenced by lowering mortality. However, a distinct subgroup of patients was strongly averse to invasive management. This highlights the importance of clarifying patient preferences to ensure treatment decisions are aligned with patient values.

Importance: Contrast-associated acute kidney injury (AKI) is a common complication of coronary angiography and percutaneous coronary intervention (PCI) that has been associated with high costs and adverse long-term outcomes., Objective: To determine whether a multifaceted intervention is effective for the prevention of AKI after coronary angiography or PCI., Design, Setting, and Participants: A stepped-wedge, cluster randomized clinical trial was conducted in Alberta, Canada, that included all invasive cardiologists at 3 cardiac catheterization laboratories who were randomized to various start dates for the intervention between January 2018 and September 2019. Eligible patients were aged 18 years or older who underwent nonemergency coronary angiography, PCI, or both; who were not undergoing dialysis; and who had a predicted AKI risk of greater than 5%. Thirty-four physicians performed 7820 procedures among 7106 patients who met the inclusion criteria. Participant follow-up ended in November 2020., Interventions: During the intervention period, cardiologists received educational outreach, computerized clinical decision support on contrast volume and hemodynamic-guided intravenous fluid targets, and audit and feedback. During the control (preintervention) period, cardiologists provided usual care and did not receive the intervention., Main Outcomes and Measures: The primary outcome was AKI. There were 12 secondary outcomes, including contrast volume, intravenous fluid administration, and major adverse cardiovascular and kidney events. The analyses were conducted using time-adjusted models., Results: Of the 34 participating cardiologists who were divided into 8 clusters by practice group and center, the intervention group included 31 who performed 4327 procedures among 4032 patients (mean age, 70.3 [SD, 10.7] years; 1384 were women [32.0%]) and the control group included 34 who performed 3493 procedures among 3251 patients (mean age, 70.2 [SD, 10.8] years; 1151 were women [33.0%]). The incidence of AKI was 7.2% (310 events after 4327 procedures) during the intervention period and 8.6% (299 events after 3493 procedures) during the control period (between-group difference, -2.3% [95% CI, -0.6% to -4.1%]; odds ratio [OR], 0.72 [95% CI, 0.56 to 0.93]; P = .01). Of 12 prespecified secondary outcomes, 8 showed no significant difference. The proportion of procedures in which excessive contrast volumes were used was reduced to 38.1% during the intervention period from 51.7% during the control period (between-group difference, -12.0% [95% CI, -14.4% to -9.4%]; OR, 0.77 [95% CI, 0.65 to 0.90]; P = .002). The proportion of procedures in eligible patients in whom insufficient intravenous fluid was given was reduced to 60.8% during the intervention period from 75.1% during the control period (between-group difference, -15.8% [95% CI, -19.7% to -12.0%]; OR, 0.68 [95% CI, 0.53 to 0.87]; P = .002). There were no significant between-group differences in major adverse cardiovascular events or major adverse kidney events., Conclusions and Relevance: Among cardiologists randomized to an intervention including clinical decision support with audit and feedback, patients undergoing coronary procedures during the intervention period were less likely to develop AKI compared with those treated during the control period, with a time-adjusted absolute risk reduction of 2.3%. Whether this intervention would show efficacy outside this study setting requires further investigation., Trial Registration: ClinicalTrials.gov Identifier: NCT03453996.

There is substantial variability in the reported incidence and outcomes of acute kidney injury (AKI). The extent to which this is attributable to differences in source populations versus methodological differences between studies is uncertain. We used 4 population-based datasets from Canada, Denmark, and the United Kingdom to measure the annual incidence and prognosis of AKI and acute kidney disease (AKD), using a homogenous analytical approach that incorporated KDIGO creatinine-based definitions and subsets of the AKI/AKD criteria. The cohorts included 7 million adults ≥18 years of age between 2011 and 2014; median age 59-68 years, 51.9-54.4% female sex. Age- and sex-standardised incidence rates for AKI or AKD were similar between regions and years; range 134.3-162.4 events/10,000 person years. Among patients who met either KDIGO 48-hour or 7-day AKI creatinine criteria, the standardised 1-year mortality was similar (30.4%-38.5%) across the cohorts, which was comparable to standardised 1-year mortality among patients who met AKI/AKD criteria using a baseline creatinine within 8-90 days prior (32.0%-37.4%). Standardised 1-year mortality was lower (21.0%-25.5% across cohorts) among patients with AKI/AKD ascertained using a baseline creatinine >90 days prior. These findings illustrate that the incidence and prognosis of AKI and AKD based on KDIGO criteria are consistent across 3 high-income countries when capture of laboratory tests is complete, creatinine-based definitions are implemented consistently within but not beyond a 90-day period, and adjustment is made for population age and sex. These approaches should be consistently applied to improve the generalizability and comparability of AKI research and clinical reporting., (Copyright © 2022 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Rationale & Objective: The KDIGO (Kidney Disease: Improving Global Outcomes) definition of acute kidney injury (AKI) is frequently used in studies to examine the epidemiology of AKI. This definition is variably interpreted and applied to routinely collected health care data. The aim of this study was to examine this variation and to achieve consensus in how AKI should be defined for research using routinely collected health care data., Sources of Evidence and Study Design: Scoping review via searching Medline and EMBASE for studies using health care data to examine AKI by using the KDIGO creatinine-based definition. An international panel of experts formed to participate in a modified Delphi process to attempt to generate consensus about how AKI should be defined when using routinely collected laboratory data., Charting Methods and Analytical Approach: The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) extension for scoping reviews was followed. For the Delphi process, 2 rounds of questions were distributed via internet-based questionnaires to all participants with a prespecified cutoff of 75% agreement used to define consensus., Results: The scoping review found 174 studies that met the inclusion criteria. The KDIGO definition was inconsistently applied, and the methods for application were poorly described. We found 58 (33%) of papers did not provide a definition of how the baseline creatinine value was determined, and only 34 (20%) defined recovery of kidney function. Of 55 invitees to the Delphi process, 35 respondents participated in round 1, and 25 participated in round 2. Some consensus was achieved in areas related to how to define the baseline creatinine value, which patients should be excluded from analysis of routinely collected laboratory data, and how persistent chronic kidney disease or nonrecovery of AKI should be defined., Limitations: The Delphi panel members predominantly came from the United Kingdom, the United States, and Canada, and there were low response rates for some questions in round 1., Conclusions: The current methods for defining AKI using routinely collected data are inconsistent and poorly described in the available literature. Experts could not achieve consensus for many aspects of defining AKI and describing its sequelae. The KDIGO guidelines should be extended to include a standardized definition for how AKI should be defined when using routinely collected data., (Copyright © 2021 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Competing Interests: M.T. James was the principal investigator of an investigator-initiated research grant from Amgen Canada. S.A. Silver received speaking fees from Baxter Canada.

Objectives: Acute kidney injury (AKI) is common after cardiac surgery. We quantified the mortality and costs of varying degrees of AKI using a population-based cohort in Alberta, Canada., Methods: A cohort of patients undergoing cardiac surgery from 2004 to 2009 was assembled from linked Alberta administrative databases. AKI was classified by Kidney Disease Improving Global Outcomes stages of severity. Our outcomes were in-hospital mortality, length of stay, and costs; among survivors, we also examined mortality and costs at 365 days. Estimates were adjusted for demographic characteristics, comorbidities, and other covariates., Results: Ten thousand one hundred seventy participants were included, of whom 9771 patients were discharged to community. Overall in-hospital mortality, costs, and length of stay were 4%, 7 days, and Can $34,000, respectively. Postcardiac surgery, AKI occurred in 25%. Compared with those without AKI, AKI was independently associated with increased in-hospital mortality across severity categories, with the highest risk (adjusted odds ratio, 37.1; 95% confidence interval, 26.3-52.1; P < .001) in patients who required acute dialysis. AKI severity was associated with increased hospital days and costs, with costs ranging from 1.21 for stage 1 AKI (95% confidence interval, 1.17-1.23) to 2.74 for acute dialysis (95% confidence interval, 2.49-3.00) (P < .001) times higher than in patients without AKI, after covariate adjustment. Postdischarge to 365 days, patients with AKI continued to experience increased costs up to 1.35-fold, and patients who required dialysis acutely continued to experience a 2.86-fold increased mortality., Conclusions: AKI remains an important indicator of mortality and health care costs postcardiac surgery., (Copyright © 2020 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

Importance: Severe acute kidney injury (AKI) is a serious postoperative complication. A tool for predicting the risk of AKI requiring kidney replacement therapy (KRT) after major noncardiac surgery might assist with patient counseling and targeted use of measures to reduce this risk., Objective: To derive and validate a predictive model for AKI requiring KRT after major noncardiac surgery., Design, Setting, and Participants: In this prognostic study, 5 risk prediction models were derived and internally validated in a population-based cohort of adults without preexisting kidney failure who underwent noncardiac surgery in Alberta, Canada, between January 1, 2004, and December 31, 2013. The best performing model and corresponding risk index were externally validated in a population-based cohort of adults without preexisting kidney failure who underwent noncardiac surgery in Ontario, Canada, between January 1, 2007, and December 31, 2017. Data analysis was conducted from September 1, 2019, to May 31, 2021., Exposures: Demographic characteristics, surgery type, laboratory measures, and comorbidities before surgery., Main Outcomes and Measures: Acute kidney injury requiring KRT within 14 days after surgery. Discrimination was assessed using the C statistic; calibration was assessed using calibration intercept and slope. Logistic recalibration was used to optimize model calibration in the external validation cohort., Results: The derivation cohort included 92 114 patients (52.2% female; mean [SD] age, 62.3 [18.0] years), and the external validation cohort included 709 086 patients (50.8% female; mean [SD] age, 61.0 [16.0] years). A total of 529 patients (0.6%) developed postoperative AKI requiring KRT in the derivation cohort, and 2956 (0.4%) developed postoperative AKI requiring KRT in the external validation cohort. The following factors were consistently associated with the risk of AKI requiring KRT: younger age (40-69 years: odds ratio [OR], 2.07 [95% CI, 1.69-2.53]; <40 years: OR, 3.73 [95% CI, 2.61-5.33]), male sex (OR, 1.55; 95% CI, 1.28-1.87), surgery type (colorectal: OR, 4.86 [95% CI, 3.28-7.18]; liver or pancreatic: OR, 6.46 [95% CI, 3.85-10.83]; other abdominal: OR, 2.19 [95% CI, 1.66-2.89]; abdominal aortic aneurysm repair: OR, 19.34 [95% CI, 14.31-26.14]; other vascular: OR, 7.30 [95% CI, 5.48-9.73]; thoracic: OR, 3.41 [95% CI, 2.07-5.59]), lower estimated glomerular filtration rate (OR, 0.97; 95% CI, 0.97-0.97 per 1 mL/min/1.73 m2 increase), lower hemoglobin concentration (OR, 0.99; 95% CI, 0.98-0.99 per 0.1 g/dL increase), albuminuria (mild: OR, 1.88 [95% CI, 1.52-2.33]; heavy: OR, 3.74 [95% CI, 2.98-4.69]), history of myocardial infarction (OR, 1.63; 95% CI, 1.32-2.03), and liver disease (mild: OR, 2.32 [95% CI, 1.66-3.24]; moderate or severe: OR, 4.96 [95% CI, 3.58-6.85]). In external validation, a final model including these variables showed excellent discrimination (C statistic, 0.95; 95% CI, 0.95-0.96), with sensitivity of 21.2%, specificity of 99.9%, positive predictive value of 38.1%, and negative predictive value of 99.7% at a predicted risk threshold of 10% or greater., Conclusions and Relevance: The findings suggest that this risk model can predict AKI requiring KRT after noncardiac surgery using routine preoperative data. The model may be feasible for implementation in clinical perioperative risk stratification for severe AKI.

Objective: The aim of this study was to examine relationships between ileostomy formation and subsequent kidney disease., Summary and Background Data: Colonic absorptive capacity loss from ileostomy formation can cause volume depletion and could result in kidney disease., Methods: We conducted a population-based cohort study comparing patients who underwent ileostomy formation with or without bowel resection (ileostomy group) to patients who underwent bowel resection without ileostomy formation (reference group). Adjusted odds ratios (aORs) for community-onset acute kidney injury (AKI) within 3 months and new-onset chronic kidney disease (CKD) within 1 year following hospital discharge were determined., Results: Among 19,889 patients, 4136 comprised the ileostomy group and 15,753 comprised the reference group; 1350 patients experienced community-onset AKI and 464 developed new-onset CKD. The aOR for community-onset AKI with ileostomy formation was 4.08 [95% confidence interval (CI) = 3.62-4.61] for any stage AKI, 7.08 (95% CI = 5.66-8.85) for stage ≥2 injury, and 7.67 (95% CI = 5.06-11.63) for stage 3 injuries. Community-onset AKI modified associations between ileostomy formation and new-onset CKD (P = 0.002). Odds of new-onset CKD were increased in the ileostomy group relative to the reference group for patients both with (aOR = 4.99; 95% CI = 3.42-7.28) and without (aOR = 2.45; 95% CI = 1.85-2.23) previous community-onset AKI episodes. In analyses comparing patients that underwent ileostomy formation and subsequent reversal within 1 year to the reference group without ileostomy, the relationship with new-onset CKD was attenuated for patients both with (aOR = 2.49; 95% CI = 1.50-4.12) and without (aOR = 0.97; 95% CI = 0.67-1.40) previous community-onset AKI episodes., Conclusions: Ileostomy formation is strongly associated with subsequent kidney disease. Vigilance for this complication and new strategies for prevention and treatment are necessary., Competing Interests: The authors report no conflict of interests., (Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc.)

Rationale & Objective: There is limited evidence to guide follow-up after acute kidney injury (AKI). Knowledge gaps include which patients to prioritize, at what time point, and for mitigation of which outcomes. In this study, we sought to compare the net benefit of risk model-based clinical decisions following AKI., Study Design: External validation of 2 risk models of AKI outcomes: the Grampian -Aberdeen (United Kingdom) AKI readmissions model and the Alberta (Canada) kidney disease risk model of chronic kidney disease (CKD) glomerular (G) filtration rate categories 4 and 5 (CKD G4 and G5). Process mining to delineate existing care pathways., Setting & Participants: Validation was based on data from adult hospital survivors of AKI from Grampian, 2011-2013., Predictors: KDIGO-based measures of AKI severity and comorbidities specified in the original models., Outcomes: Death or readmission within 90 days for all hospital survivors. Progression to new CKD G4-G5 for patients surviving at least 90 days after AKI., Analytical Approach: Decision curve analysis to assess the "net benefit" of use of risk models to guide clinical care compared to alternative approaches (eg, prioritizing all AKI, severe AKI, or only those without kidney recovery)., Results: 26,575 of 105,461 hospital survivors in Grampian (mean age, 60.9 ± 19.8 [SD] years) were included for validation of the death or readmission model, and 9,382 patients (mean age, 60.9 ± 19.8 years) for the CKD G4-G5 model. Both models discriminated well (area under the curve [AUC], 0.77 and 0.86, respectively). Decision curve analysis showed greater net benefit for follow up of all AKI than only severe AKI in most cases. Both original and refitted models provided net benefit superior to any other decision strategy. In process mining of all hospital discharges, 41% of readmissions and deaths occurred among people recovering after AKI. 1,464 of 3,776 people (39%) readmitted after AKI had received no intervening monitoring., Limitations: Both original models overstated risks, indicating a need for regular updating., Conclusions: Follow up after AKI has potential net benefit for preempting readmissions, death, and subsequent CKD progression. Decisions could be improved by using risk models and by focusing on AKI across a full spectrum of severity. The current lack of monitoring among many with poor outcomes indicates possible opportunities for implementation of decision support., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Acute kidney injury (AKI) is common after surgery and associated with increased mortality, costs, and lengths of hospitalization. We examined associations between angiotensin-converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB), diuretic, or nonsteroidal anti-inflammatory drug (NSAID) use after major surgery and AKI., Materials and Methods: We conducted a nested case-control study of patients who underwent major cardiac, thoracic, general, or vascular surgery in Calgary, Alberta, Canada. Cases with AKI were matched on age, gender, and surgery type with up to five controls without AKI within 30-d after surgery. Adjusted odds ratios (ORs) for AKI were determined based on postoperative administration of ACEIs/ARBs, diuretics, or NSAIDs., Results: Among 33,648 patients in the cohort, 2911 cases with AKI were matched to 9309 controls without AKI. Postoperative diuretic [OR = 1.96; 95% confidence interval (CI) = 1.68-2.29], but not ACEI/ARB (OR = 0.83; 95% CI = 0.72-0.95) or NSAID (OR = 1.12; 95% CI = 0.96-1.31), use was independently associated with higher odds of AKI (including stages 1 and 2/3 AKI) after all types of major surgery. There were increased adjusted odds of AKI 1 to 5 d after first exposure to diuretics and 1 d after first exposure to NSAIDs (but not after later exposures). Relationships between ACEI/ARB use and AKI varied by surgery type (p-interaction = 0.004), with lower odds of AKI observed among ACEI/ARB use after cardiac surgery (OR = 0.70; 95% CI = 0.57-0.81), but no difference after other major surgeries., Conclusions: Postoperative administration of diuretics and NSAIDs was associated with increased odds of AKI after major surgery. These findings characterize potentially modifiable medication exposures associated with AKI after surgery., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Acute kidney injury (AKI) is common in hospitalized patients and is associated with poor patient outcomes and high costs of care. The implementation of clinical decision support tools within electronic medical record (EMR) could improve AKI care and outcomes. While clinical decision support tools have the potential to enhance recognition and management of AKI, there is limited description in the literature of how these tools were developed and whether they meet end-user expectations., Methods: We developed and evaluated the content, acceptability, and usability of electronic clinical decision support tools for AKI care. Multi-component tools were developed within a hospital EMR (Sunrise Clinical Manager™, Allscripts Healthcare Solutions Inc.) currently deployed in Calgary, Alberta, and included: AKI stage alerts, AKI adverse medication warnings, AKI clinical summary dashboard, and an AKI order set. The clinical decision support was developed for use by multiple healthcare providers at the time and point of care on general medical and surgical units. Functional and usability testing for the alerts and clinical summary dashboard was conducted via in-person evaluation sessions, interviews, and surveys of care providers. Formal user acceptance testing with clinical end-users, including physicians and nursing staff, was conducted to evaluate the AKI order set., Results: Considerations for appropriate deployment of both non-disruptive and interruptive functions was important to gain acceptability by clinicians. Functional testing and usability surveys for the alerts and clinical summary dashboard indicated that the tools were operating as desired and 74% (17/23) of surveyed healthcare providers reported that these tools were easy to use and could be learned quickly. Over three-quarters of providers (18/23) reported that they would utilize the tools in their practice. Three-quarters of the participants (13/17) in user acceptance testing agreed that recommendations within the order set were useful. Overall, 88% (15/17) believed that the order set would improve the care and management of AKI patients., Conclusions: Development and testing of EMR-based decision support tools for AKI with clinicians led to high acceptance by clinical end-users. Subsequent implementation within clinical environments will require end-user education and engagement in system-level initiatives to use the tools to improve care.

Purpose: Severe acute kidney injury (AKI) is associated with a significant risk of mortality and persistent renal replacement therapy (RRT) dependence. The objective of this study was to develop prediction models for mortality at 90-day and 1-year following RRT initiation in critically ill patients with AKI., Methods: All patients who commenced RRT in the intensive care unit for AKI at a tertiary care hospital between 2007 and 2014 constituted the development cohort. We evaluated the external validity of our mortality models using data from the multicentre OPTIMAL-AKI study., Results: The development cohort consisted of 594 patients, of whom 320(54%) died and 40 (15% of surviving patients) remained RRT-dependent at 90-day Eleven variables were included in the model to predict 90-day mortality (AUC:0.79, 95%CI:0.76-0.82). The performance of the 90-day mortality model declined upon validation in the OPTIMAL-AKI cohort (AUC:0.61, 95%CI:0.54-0.69) and showed modest calibration. Similar results were obtained for mortality model at 1-year., Conclusions: Routinely collected variables at the time of RRT initiation have limited ability to predict mortality in critically ill patients with AKI who commence RRT., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests, (Copyright © 2019 Elsevier Inc. All rights reserved.)

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.

Background: Identifying patients at increased risk of contrast-associated acute kidney injury (CA-AKI) can help target risk mitigation strategies toward these individuals during percutaneous coronary intervention. Illuminating which risk models best stratify risk is an important foundation for such quality improvement efforts., Methods and Results: Seven previously published risk prediction models for CA-AKI and 3 models for kidney injury requiring dialysis were validated using 2 definitions for CA-AKI (the Kidney Disease: Improving Global Outcomes definition of ≥0.3 mg/dL within 48 hours or ≥50% increase in serum creatinine from baseline within 7 days and the historical definition of ≥0.5 mg/dL or ≥25% increase in serum creatinine from baseline within 48 hours), and AKI requiring dialysis within 30 days of percutaneous coronary intervention. Model performance was compared based on discrimination, calibration, and categorical net reclassification index before and after model recalibration. Among 7888 patients who underwent percutaneous coronary intervention in Alberta Canada, CA-AKI occurred in 330 patients (4.2%) when CA-AKI was defined using the Kidney Disease: Improving Global Outcomes definition and 571 (7.3%) when using the historical definition. CA-AKI requiring dialysis occurred in 42 (0.6%) patients. When validated using the Kidney Disease: Improving Global Outcomes definition for CA-AKI, the 2 most recently published models for CA-AKI showed better discrimination (C statistics, 0.75-0.76) than older models (C statistics, 0.61-0.68). C statistics of models for kidney injury requiring dialysis ranged from 0.70 to 0.86. The calibration of all models for CA-AKI deviated from ideal, and the proportion of patients classified into different risk categories for CA-AKI differed substantially for the 2 most recent models. Recalibration significantly improved risk stratification of patients into clinical risk categories for some models., Conclusions: Recent prediction models for CA-AKI show better discrimination compared with older models; however, model recalibration should be examined in external cohorts to improve the accuracy of predictions, particularly if predicted risk strata are used to guide management approaches.

Background: Contrast-induced acute kidney injury (CI-AKI) is a common and serious complication of invasive cardiac procedures. Quality improvement programs have been associated with a lower incidence of CI-AKI over time, but there is a lack of high-quality evidence on clinical decision support for prevention of CI-AKI and its impact on processes of care and clinical outcomes., Methods: The Contrast-Reducing Injury Sustained by Kidneys (Contrast RISK) study will implement an evidence-based multifaceted intervention designed to reduce the incidence of CI-AKI, encompassing automated identification of patients at increased risk for CI-AKI, point-of-care information on safe contrast volume targets, personalized recommendations for hemodynamic optimization of intravenous fluids, and follow-up information for patients at risk. Implementation will use cardiologist academic detailing, computerized clinical decision support, and audit and feedback. All 31 physicians practicing in all 3 of Alberta's cardiac catheterization laboratories will participate using a cluster-randomized stepped-wedge design. The order in which they are introduced to this intervention will be randomized within 8 clusters. The primary outcome is CI-AKI incidence, with secondary outcomes of CI-AKI avoidance strategies and downstream adverse major kidney and cardiovascular events. An economic evaluation will accompany the main trial., Conclusions: The Contrast RISK study leverages information technology systems to identify patient risk combined with evidence-based protocols, audit, and feedback to reduce CI-AKI in cardiac catheterization laboratories across Alberta. If effective, this intervention can be broadly scaled and sustained to improve the safety of cardiac catheterization., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Importance: Abnormal measurements of kidney function or structure may be identified that do not meet criteria for acute kidney injury (AKI) or chronic kidney disease (CKD) but nonetheless may require medical attention. The Kidney Disease: Improving Global Outcomes Clinical Practice Guideline for AKI proposed criteria for the definition of acute kidney diseases and disorders (AKD), which include AKI; however, the incidence and prognosis of AKD without AKI remain unknown., Objective: To characterize the incidence and outcomes of AKD without AKI, with or without CKD., Design, Setting, and Participants: Retrospective cohort study including all adult residents in a universal health care system in Alberta, Canada, without end-stage kidney disease (ESKD) and with at least 1 serum creatinine measurement between January 1 and December 31, 2008, in a community or hospital setting. Data analysis took place in 2018., Main Outcomes and Measures: The Kidney Disease: Improving Global Outcomes guideline definitions for CKD, AKI, and AKD based on serum creatinine, estimated glomerular filtration rate, and albuminuria criteria were applied to estimate the proportion of patients with CKD, AKI, and AKD without AKI, and combinations of the conditions. Patients were followed up for up to 8 years (study end date, June 31, 2016) to characterize their risks of mortality, development of new CKD, progression of preexisting CKD, and ESKD., Results: Among 1 109 099 Alberta residents included in the cohort, the mean (SD) age was 52.3 (17.6) years, and 43.0% were male. Findings showed that AKD without AKI was common (3.8 individuals without preexisting CKD and 0.6 with preexisting CKD per 100 population tested). In Cox proportional hazards and competing risks models over a median (interquartile range) of 6.0 (5.7-6.3) years of follow-up, AKD without AKI (compared with no kidney disease) was associated with higher risks of developing new CKD (37.4% vs 7.4%%; adjusted sub-hazard ratio [sHR], 3.17; 95% CI, 3.10-3.23), progression of preexisting CKD (49.5% vs 34.6%; adjusted sHR, 1.38; 95% CI, 1.33-1.44), ESKD (0.6% vs 0.1%; adjusted sHR, 8.56; 95% CI, 7.32-10.01), and death (25.8% vs 7.3%; adjusted hazard ratio, 1.42; 95% CI, 1.39-1.45)., Conclusions and Relevance: Criteria for AKD identified many patients who did not meet the criteria for CKD or AKI but had overall modestly increased risks of incident and progressive CKD, ESKD, and death. The clinical importance of AKD remains to be determined.

Background: As more patients at lower cardiovascular (CV) risk are treated with statins, the balance between cardiovascular benefits and the risk of adverse events becomes increasingly important., Methods: We did a population-based cohort study (May 1, 2002 to March 30, 2013) using province-wide laboratory and administrative data in Alberta. We studied new statin users aged 66 years of age and older who were not receiving renal replacement therapy at baseline. We assessed statin use at 30-day intervals to allow time-varying assessment of statin exposure in Cox proportional hazards models that examined the relation between statin use and hospitalization with acute kidney injury (AKI)., Results: Of the 128,140 new statin users, 47 and 46% were prescribed high- and medium-intensity regimens at the index date. During median follow-up of 4.6 years (interquartile range 2.2, 7.4), 9118 individuals were hospitalized for AKI. Compared to non-use, the use of high- and medium-intensity statin regimens was associated with significant increases in the adjusted risks of hospitalization with AKI: hazard ratios 1.16 [95% confidence interval (CI) 1.10, 1.23] and 1.07 (95% CI 1.01, 1.13), respectively. Risks of AKI were higher among women than men, and among users of angiotensin converting enzyme inhibitors/angiotensin receptor blockers than non-users, and among diuretic users (p for interaction 0.002, 0.01, and 0.04 respectively)., Conclusions: We found a graded, independent association between the intensity of statin use and the risk of hospitalization with AKI, although the absolute magnitude of the excess risk was small.

Importance: Patients with acute kidney injury (AKI) are at an increased long-term risk of death. Effective strategies that improve long-term outcomes in patients with AKI are unknown., Objective: To evaluate whether the use of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) after hospital discharge is associated with better outcomes in patients with AKI., Design, Setting, and Participants: This retrospective cohort study used data from the Alberta Kidney Disease Network population database to evaluate 46 253 adults 18 years or older with an episode of AKI during a hospitalization between July 1, 2008, and March 31, 2015, in Alberta, Canada. All patients who survived to hospital discharge were followed up for a minimum of 2 years., Exposures: Use of an ACEI or ARB within 6 months after hospital discharge., Main Outcomes and Measures: The primary outcome was mortality; secondary outcomes included hospitalization for a renal cause, end-stage renal disease (ESRD), and a composite outcome of ESRD or sustained doubling of serum creatinine concentration. An AKI was defined as a 50% increase between prehospital and peak in-hospital serum creatinine concentrations. Propensity scores were used to construct a matched-pairs cohort of patients who did and did not have a prescription for an ACEI or ARB within 6 months after hospital discharge., Results: The study evaluated 46 253 adults (mean [SD] age, 68.6 [16.4] years; 24 436 [52.8%] male). Within 6 months of discharge, 22 193 (48.0%) of the participants were prescribed an ACEI or ARB. After adjustment for comorbidities, ACEI or ARB use before admission, demographics, baseline kidney function, other factors related to index hospitalization, and prior health care services, ACEI or ARB use was associated with lower mortality in patients with AKI after 2 years (adjusted hazard ratio, 0.85; 95% CI, 0.81-0.89). However, patients who received an ACEI or ARB had a higher risk of hospitalization for a renal cause (adjusted hazard ratio, 1.28; 95% CI, 1.12-1.46). No association was found between ACEI or ARB use and progression to ESRD., Conclusions and Relevance: Among patients with AKI, ACEI or ARB therapy appeared to be associated with lower mortality but a higher risk of hospitalization for a renal cause. These results suggest a potential benefit of ACEI or ARB use after AKI, but cautious monitoring for renal-specific complications may be warranted.

Background: Acute kidney injury (AKI) is associated with increased morbidity and mortality after liver resection. Patients with hepatocellular carcinoma (HCC) have a higher risk of AKI owing to the underlying association between hepatic and renal dysfunction. Use of the Acute Kidney Injury Network (AKIN) diagnostic criteria is recommended for patients with cirrhosis, but remains poorly studied following liver resection. We compared the prognostic value of the AKIN creatinine and urine output criteria in terms of postoperative outcomes following liver resection for HCC., Methods: All patients who underwent a liver resection for HCC from January 2010 to June 2016 were included. We used AKIN urine output and creatinine criteria to assess for AKI within 48 hours of surgery., Results: Eighty liver resections were performed during the study period. Cirrhosis was confirmed in 80%. Median hospital stay was 9 (interquartile range 7–12) days, and 30-day mortality was 2.5%. The incidence of AKI was higher based on the urine output than on the creatinine criterion (53.8% v. 20%), and was associated with prolonged hospitalization and 30-day postoperative mortality when defined by serum creatinine (hospital stay: 11.2 v. 20.1 d, p = 0.01; mortality: 12.5% v. 0%, p < 0.01), but not urine output (hospital stay: 15.6 v. 10 d, p = 0.05; mortality: 2.3% v. 2.7%, p > 0.99)., Conclusion: The urine output criterion resulted in an overestimation of AKI and compromised the prognostic value of AKIN criteria. Revision may be required to account for the exacerbated physiologic postoperative reduction in urine output in patients with HCC., Competing Interests: None declared.

Radiographic contrast agents cause acute kidney injury (AKI), yet the underlying pathogenesis is poorly understood. Nod-like receptor pyrin containing 3-deficient (Nlrp3-deficient) mice displayed reduced epithelial cell injury and inflammation in the kidney in a model of contrast-induced AKI (CI-AKI). Unexpectedly, contrast agents directly induced tubular epithelial cell death in vitro that was not dependent on Nlrp3. Rather, contrast agents activated the canonical Nlrp3 inflammasome in macrophages. Intravital microscopy revealed diatrizoate (DTA) uptake within minutes in perivascular CX3CR1+ resident phagocytes in the kidney. Following rapid filtration into the tubular luminal space, DTA was reabsorbed and concentrated in tubular epithelial cells via the brush border enzyme dipeptidase-1 in volume-depleted but not euvolemic mice. LysM-GFP+ macrophages recruited to the kidney interstitial space ingested contrast material transported from the urine via direct interactions with tubules. CI-AKI was dependent on resident renal phagocytes, IL-1, leukocyte recruitment, and dipeptidase-1. Levels of the inflammasome-related urinary biomarkers IL-18 and caspase-1 were increased immediately following contrast administration in patients undergoing coronary angiography, consistent with the acute renal effects observed in mice. Taken together, these data show that CI-AKI is a multistep process that involves immune surveillance by resident and infiltrating renal phagocytes, Nlrp3-dependent inflammation, and the tubular reabsorption of contrast via dipeptidase-1.

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.

Acute kidney injury is a heterogeneous group of conditions characterized by a sudden decrease in glomerular filtration rate, manifested by an increase in serum creatinine concentration or oliguria, and classified by stage and cause. This type of injury occurs in approximately 20% of hospitalized patients, with major complications including volume overload, electrolyte disorders, uremic complications, and drug toxicity. Management includes specific treatments according to the underlying cause and supportive treatment to prevent and manage complications. Kidney replacement therapy is used when complications cannot be managed with medical therapy alone. Despite advances in care, the mortality rate in patients requiring kidney replacement therapy remains approximately 50%.

Background and Objectives: Recent guidelines suggest that patients should be evaluated after AKI for resolution versus progression of CKD. There is uncertainty as to the role of nephrologists in this process. The objective of this study was to compare the follow-up recommendations from nephrologists with contemporary processes of care for varying scenarios of patients hospitalized with AKI., Design, Setting Participants, & Measurements: We surveyed Canadian nephrologists using a series of clinical vignettes of patients hospitalized with severe AKI and asked them to rank their likelihood of recommending follow-up for each patient after hospital discharge. We compared these responses with administrative health data on rates of community follow-up with nephrologists for patients hospitalized with AKI in Alberta, Canada between 2005 and 2014., Results: One hundred forty-five nephrologists participated in the survey (46% of the physician membership of the Canadian Society of Nephrology). Nephrologists surveyed indicated that they would definitely or probably re-evaluate patients in 87% of the scenarios provided, with a higher likelihood of follow-up for patients with a history of preexisting CKD (89%), heart failure (92%), receipt of acute dialysis (91%), and less complete recovery of kidney function (98%). In contrast, only 24% of patients with similar characteristics were seen by a nephrologist in Alberta within 1 year after a hospitalization with AKI, with a trend toward lower rates of follow-up over more recent years of the study. Follow-up with a nephrologist was significantly less common among patients over the age of 80 years old (20%) and more common among patients with preexisting CKD (43%) or a nephrology consultation before or during AKI hospitalization (78% and 41%, respectively)., Conclusions: There is a substantial disparity between the opinions of nephrologists and actual processes of care for nephrology evaluation of patients after hospitalization with severe AKI., (Copyright © 2017 by the American Society of Nephrology.)

Background: Identification of patients at risk of contrast-induced acute kidney injury (CI-AKI) is valuable for targeted prevention strategies accompanying cardiac catheterization., Methods: We searched MedLine and EMBASE for articles that developed or validated a clinical prediction model for CI-AKI or dialysis after angiography or percutaneous coronary intervention. Random effects meta-analysis was used to pool c-statistics of models. Heterogeneity was explored using stratified analyses and meta-regression., Results: We identified 75 articles describing 74 models predicting CI-AKI, 10 predicting CI-AKI and dialysis, and 1 predicting dialysis. Sixty-three developed a new risk model whereas 20 articles reported external validation of previously developed models. Thirty models included sufficient information to obtain individual patient risk estimates; 9 using only preprocedure variables whereas 21 included preprocedural and postprocedure variables. There was heterogeneity in the discrimination of CI-AKI prediction models (median [total range] in c-statistic 0.78 [0.57-0.95]; I 2  = 95.8%, Cochran Q-statistic P < 0.001). However, there was no difference in the discrimination of models using only preprocedure variables compared with models that included postprocedural variables (P = 0.868). Models predicting dialysis had good discrimination without heterogeneity (median [total range] c-statistic: 0.88 [0.87-0.89]; I 2  = 0.0%, Cochran Q-statistic P = 0.981). Seven prediction models were externally validated; however, 2 of these models showed heterogeneous discriminative performance and 2 others lacked information on calibration in external cohorts., Conclusions: Three published models were identified that produced generalizable risk estimates for predicting CI-AKI. Further research is needed to evaluate the effect of their implementation in clinical care., (Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Background: Current guidelines recommend staging acute kidney injury (AKI) according to the serum creatinine (SCr) or urine output (UO) criteria that achieve the highest stage. There is little information about the implications of adding UO to SCr measurements for staging AKI outside intensive care units and after cardiac surgery., Methods: We performed a cohort study of all adults without end-stage renal disease who underwent major noncardiac surgery between January 2005 and March 2011 in Calgary, AB, Canada. Participants required at least two SCr and UO measurements to be included. We examined the implications of adding UO to SCr to stage AKI based on Kidney Disease: Improving Global Outcomes criteria. Logistic and linear regression models were used to examine the associations between AKI stage and 30-day mortality or hospital length of stay (LOS), respectively., Results: A total of 4229 (17%) surgical patients had sufficient SCr and UO measurements for inclusion in the cohort. The apparent incidence of postoperative AKI substantially increased with the addition of UO to SCr criteria (8.1% with SCr alone versus 64.0% with SCr and UO). Mortality for a given stage of AKI was lower when UO was added to SCr criteria (0.3, 3.2, 1.9 and 3.0% for no AKI and Stages 1, 2 and 3, respectively) versus with SCr alone (1.2, 4.2, 15.4 and 12.8%). However, among participants without AKI based on the SCr criterion, the odds of mortality and mean LOS both significantly increased with lower UO. Models that reclassified AKI stage based on UO in addition SCr criteria had the best discrimination for mortality and LOS., Conclusions: Adding UO to SCr criteria substantially increases the apparent incidence of AKI on hospital wards and significantly changes the prognostic implications of AKI identification and staging. These measures should not be considered equivalent criteria in AKI staging., (© The Author 2016. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)

Background: The implementation of new serum creatinine (SCr)-based criteria for acute kidney injury (AKI) has brought to light several areas of uncertainty in patients with cirrhosis., Study Design: Population-based cohort study., Setting & Participants: Adults with cirrhosis hospitalized between 2002-2012., Predictor: We aimed to address the prognostic implications of the new AKI criteria in cirrhosis., Outcomes: Baseline kidney function was defined from all outpatient SCr within 3 months before hospitalization. Cox proportional hazards models were fit to examine associations between AKI, renal recovery and all-cause mortality., Results: 4,733 patients were studied. The 30-day mortality was higher for participants with AKI (43.9% vs 8.5%; p-value<0.001), and increased with AKI severity. The highest incidence of AKI occurred when the lowest SCr within the three months prior to admission was used to define baseline. The hazard ratio for mortality using the lowest SCr within 3 months and the closest pre-admission SCr (definition suggested by the recent consensus guideline) were similar, validating the use of the latter measure. As compared to patients without AKI, stage 1 AKI with maximum SCr ≤132 mmol/L remained associated with a 3.5-fold increased hazard of death at 30 days (95% CI 2.6 to 4.7)., Limitations: As an observational study, the results were vulnerable to residual confounding and ascertainment bias in the use of laboratory data to identify AKI. We did not have access to liver function or disease etiology variables and were unable to adjust for these in our analyses., Conclusions: These results confirm the graded relationship between AKI severity, renal recovery, and mortality and further clarify previously discordant reports about the prognostic relevance of new AKI criteria in patients with cirrhosis.

Background: Acute kidney injury (AKI) is a serious complication of major noncardiac surgery. Risk prediction models for AKI following noncardiac surgery may be useful for identifying high-risk patients to target with prevention strategies., Methods: We conducted a systematic review of risk prediction models for AKI following major noncardiac surgery. MEDLINE, EMBASE, BIOSIS Previews and Web of Science were searched for articles that (i) developed or validated a prediction model for AKI following major noncardiac surgery or (ii) assessed the impact of a model for predicting AKI following major noncardiac surgery that has been implemented in a clinical setting., Results: We identified seven models from six articles that described a risk prediction model for AKI following major noncardiac surgeries. Three studies developed prediction models for AKI requiring renal replacement therapy following liver transplantation, three derived prediction models for AKI based on the Risk, Injury, Failure, Loss of kidney function, End-stage kidney disease (RIFLE) criteria following liver resection and one study developed a prediction model for AKI following major noncardiac surgical procedures. The final models included between 4 and 11 independent variables, and c-statistics ranged from 0.79 to 0.90. None of the models were externally validated., Conclusions: Risk prediction models for AKI after major noncardiac surgery are available; however, these models lack validation, studies of clinical implementation and impact analyses. Further research is needed to develop, validate and study the clinical impact of such models before broad clinical uptake., (© The Author 2015. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)

Background: Diabetes mellitus and hypertension are risk factors for acute kidney injury (AKI). Whether estimated glomerular filtration rate (eGFR) and urine albumin-creatinine ratio (ACR) remain risk factors for AKI in the presence and absence of these conditions is uncertain., Study Design: Meta-analysis of cohort studies., Setting & Population: 8 general-population (1,285,045 participants) and 5 chronic kidney disease (CKD; 79,519 participants) cohorts., Selection Criteria for Studies: Cohorts participating in the CKD Prognosis Consortium., Predictors: Diabetes and hypertension status, eGFR by the 2009 CKD Epidemiology Collaboration creatinine equation, urine ACR, and interactions., Outcome: Hospitalization with AKI, using Cox proportional hazards models to estimate HRs of AKI and random-effects meta-analysis to pool results., Results: During a mean follow-up of 4 years, there were 16,480 episodes of AKI in the general-population and 2,087 episodes in the CKD cohorts. Low eGFRs and high ACRs were associated with higher risks of AKI in individuals with or without diabetes and with or without hypertension. When compared to a common reference of eGFR of 80mL/min/1.73m(2) in nondiabetic patients, HRs for AKI were generally higher in diabetic patients at any level of eGFR. The same was true for diabetic patients at all levels of ACR compared with nondiabetic patients. The risk gradient for AKI with lower eGFRs was greater in those without diabetes than with diabetes, but similar with higher ACRs in those without versus with diabetes. Those with hypertension had a higher risk of AKI at eGFRs>60mL/min/1.73m(2) than those without hypertension. However, risk gradients for AKI with both lower eGFRs and higher ACRs were greater for those without than with hypertension., Limitations: AKI identified by diagnostic code., Conclusions: Lower eGFRs and higher ACRs are associated with higher risks of AKI among individuals with or without either diabetes or hypertension., (Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Robust estimates and sources of variation in risks of clinical outcomes for cardiopulmonary bypass (CPB)-associated acute kidney injury (AKI) are needed to inform clinical practice and policy. We aimed to assess whether the methods for defining acute kidney disease modify the estimated association of AKI with CPB., Study Design: Systematic review and meta-analysis., Setting & Population: Adults undergoing CPB., Selection Criteria for Studies: Cohort studies reporting adjusted associations between CPB-associated AKI and early mortality, later mortality, stroke, myocardial infarction, congestive heart failure, all-cause hospitalization, chronic kidney disease, end-stage kidney disease, bleeding complications, or perioperative infection., Predictors: CPB-associated AKI and renal replacement therapy., Outcomes: The primary outcome was early mortality (in-hospital or within 90 days of surgery) in studies reporting adjusted associations and secondary outcomes including total and cardiovascular mortality, major adverse cardiovascular events, rehospitalization, end-stage kidney disease, bleeding, and perioperative infection., Results: 46 studies with 47 unique cohorts comprising 242,388 participants were included. The pooled rate of CPB-associated AKI was 18.2%, and of renal replacement therapy, 2.1%. CPB-associated AKI was associated with early mortality (risk ratio [RR], 4.0; 95% CI, 3.1-5.2; crude mortality with CPB-associated AKI, 4.6%; without CPB-AKI, 1.5%) with considerable heterogeneity between studies (I(2)=87%). The AKI definition did not modify prognostic estimates (P for subgroup analysis = 0.9). When heterogeneity was fully accounted for using credibility ceilings, risks of early mortality were attenuated (RR, 2.2; 95% CI, 1.8-2.8) but remained high. Renal replacement therapy also was associated with early mortality (RR, 5.3; 95% CI, 3.4-8.1). CPB-associated AKI also was associated with long-term mortality (RR, 2.0; 95% CI, 1.7-2.3) and stroke (RR, 2.2; 95% CI, 1.1-4.5). No other outcomes were reported in more than 3 studies., Limitations: Unclear attrition from follow-up in most studies and variable adjustment for confounders across studies., Conclusions: CPB-associated AKI is associated with a more than 2-fold increase in early mortality regardless of AKI definition., (Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Quality indicators are measurements of healthcare outcome, process, or structure that can be used as tools to measure the quality of care and identify opportunities for improvement. Acute kidney injury (AKI) has many characteristics that make it a potential target for quality indicator development. It is common, associated with a high risk of adverse outcomes, and there are reports of gaps in the quality of care in several clinical settings despite publication of evidence-based guidelines. Substantial work has already been undertaken to develop quality measures related to AKI following percutaneous coronary interventions and major surgical procedures. This paper reviews the current literature that has addressed issues of prevention or management of AKI as outcome, process, or structure quality indicators in these clinical settings. Several current controversies about the appropriateness of such indicators related to AKI are identified. Further research to strengthen the evidence-base supporting prevention and management initiatives for AKI across all relevant clinical settings is needed to clarify the role of AKI as a target for clinical quality indicators., (© 2015 S. Karger AG, Basel.)

Recent efforts have standardized definitions and classification systems for acute kidney injury (AKI) and chronic kidney disease (CKD). These efforts have enhanced communication, recognition, and awareness of acute and CKDs and stimulated research on both disorders. However, abnormalities of kidney function and structure can occur that do not meet the current criteria for either disorder. Recognizing the need for a uniform approach encompassing both acute and chronic abnormalities of kidney function and structure, the Kidney Disease Improving Global Outcomes 2012 Clinical Practice Guideline for AKI Guidelines proposed an operational definition for acute kidney diseases and disorders (AKD) that encompasses both AKI and any newly recognized kidney disease that does not meet the current definitions for AKI or CKD. Recent commentaries have highlighted that it may be premature to adopt these criteria into clinical practice, but that they may be useful for application in epidemiologic studies. Future research is needed to better understand the clinical characteristics, incidence, and prognosis of AKD, as well as the implications of case identification based on the AKD criteria., (© 2015 S. Karger AG, Basel.)

Background and Objectives: AKI after coronary angiography is associated with poor long-term outcomes. The relationship between contrast-associated AKI and subsequent use of prognosis-modifying cardiovascular medications is unknown., Design, Setting, Participants, & Measurements: A cohort study of 5911 participants 66 years of age or older with acute coronary syndrome who received a coronary angiogram in Alberta, Canada was performed between November 1, 2002, and November 30, 2008. AKI was identified according to Kidney Disease Improving Global Outcomes AKI criteria., Results: In multivariable logistic regression models, compared with participants without AKI, those with stages 1 and 2-3 AKI had lower odds of subsequent use of angiotensin-converting enzyme inhibitors/angiotensin receptor blocker within 120 days of hospital discharge (adjusted odds ratio, 0.65; 95% confidence interval, 0.53 to 0.80 and odds ratio, 0.34; 95% confidence interval, 0.23 to 0.48, respectively). Subsequent statin and β-blockers use within 120 days of hospital discharge was significantly lower among those with stages 2-3 AKI (adjusted odds ratio, 0.44; 95% confidence interval, 0.31 to 0.64 and odds ratio, 0.46; 95% confidence interval, 0.31 to 0.66, respectively). These associations were consistently seen in patients with diabetes mellitus, heart failure, low baseline eGFR, and albuminuria; 952 participants died during subsequent follow-up after hospital discharge (mean=3.1 years). The use of each class of cardiovascular medication was associated with lower mortality, including among those who had experienced AKI., Conclusions: Strategies to optimize the use of cardiac medications in people with AKI after coronary angiography might improve care., (Copyright © 2014 by the American Society of Nephrology.)

Background: Survivors of acute kidney injury are at an increased risk of developing irreversible deterioration in kidney function and in some cases, the need for chronic dialysis. We aimed to determine predictors of chronic dialysis and death among survivors of dialysis-requiring acute kidney injury., Methods: We used linked administrative databases in Ontario, Canada, to identify patients who were discharged from hospital after an episode of acute kidney injury requiring dialysis and remained free of further dialysis for at least 90 days after discharge between 1996 and 2009. Follow-up extended until March 31, 2011. The primary outcome was progression to chronic dialysis. Predictors for this outcome were evaluated using cause-specific Cox proportional hazards models, and a competing risk approach was used to calculate absolute risk., Results: We identified 4 383 patients with acute kidney injury requiring temporary in-hospital dialysis who survived to discharge. After a mean follow-up of 2.4 years, 356 (8%) patients initiated chronic dialysis and 1475 (34%) died. The cumulative risk of chronic dialysis was 13.5% by the Kaplan-Meier method, and 10.3% using a competing risk approach. After accounting for the competing risk of death, previous nephrology consultation (subdistribution hazard ratio (sHR) 2.03; 95% confidence interval (CI) 1.61-2.58), a history of chronic kidney disease (sHR3.86; 95% CI 2.99-4.98), a higher Charlson comorbidity index score (sHR 1.10; 95% CI 1.05-1.15/per unit) and pre-existing hypertension (sHR 1.82; 95% CI 1.28-2.58) were significantly associated with an increased risk of progression to chronic dialysis., Conclusions: Among survivors of dialysis-requiring acute kidney injury who initially become dialysis independent, the subsequent need for chronic dialysis is predicted by pre-existing kidney disease, hypertension and global comorbidity. This information can identify patients at high risk of progressive kidney disease who may benefit from closer surveillance after cessation of the acute phase of illness.

Purpose of Review: People with chronic kidney disease (CKD) are less likely to receive early-invasive management of acute coronary syndrome (ACS). The purpose of this article is to review the risks and outcomes of early-invasive versus conservative strategies, and to consider how contrast-induced acute kidney injury (CI-AKI) should factor in treatment decisions for people with CKD., Recent Findings: Numerous observational studies have characterized the prognostic importance of CI-AKI. However, recent studies illustrate that compared to the risk of AKI in individuals treated conservatively, the additional risk of kidney injury associated with invasive coronary procedures is relatively modest. Despite the risk of CI-AKI, early-invasive management of ACS has been associated with important long-term benefits., Summary: These findings illustrate that the additional short-term risk of AKI associated with invasive management should be considered alongside long-term treatment effects on other clinical outcomes and should not act as a deterrent to their use. Strategies to increase the uptake of an invasive management approach, accompanied by the use of CI-AKI prevention strategies, could benefit high-risk individuals with CKD.

Background: Some studies but not others suggest angiotensin converting enzyme inhibitor (ACEi) or angiotensin receptor blocker (ARB) use prior to major surgery associates with a higher risk of postoperative acute kidney injury (AKI) and death., Methods: We conducted a large population-based retrospective cohort study of patients aged 66 years or older who received major elective surgery in 118 hospitals in Ontario, Canada from 1995 to 2010 (n = 237,208). We grouped the cohort into ACEi/ARB users (n = 101,494) and non-users (n = 135,714) according to whether the patient filled at least one prescription for an ACEi or ARB (or not) in the 120 days prior to surgery. Our study outcomes were acute kidney injury treated with dialysis (AKI-D) within 14 days of surgery and all-cause mortality within 90 days of surgery., Results: After adjusting for potential confounders, preoperative ACEi/ARB use versus non-use was associated with 17% lower risk of post-operative AKI-D (adjusted relative risk (RR): 0.83; 95% confidence interval (CI): 0.71 to 0.98) and 9% lower risk of all-cause mortality (adjusted RR: 0.91; 95% CI: 0.87 to 0.95). Propensity score matched analyses provided similar results. The association between ACEi/ARB and AKI-D was significantly modified by the presence of preoperative chronic kidney disease (CKD) (P value for interaction < 0.001) with the observed association evident only in patients with CKD (CKD - adjusted RR: 0.62; 95% CI: 0.50 to 0.78 versus No CKD: adjusted RR: 1.00; 95% CI: 0.81 to 1.24)., Conclusions: In this cohort study, preoperative ACEi/ARB use versus non-use was associated with a lower risk of AKI-D, and the association was primarily evident in patients with CKD. Large, multi-centre randomized trials are needed to inform optimal ACEi/ARB use in the peri-operative setting.

Objective: To quantify an association between acute kidney injury and use of high potency statins versus low potency statins., Design: Retrospective observational analysis of administrative databases, using nine population based cohort studies and meta-analysis. We performed as treated analyses in each database with a nested case-control design. Rate ratios for different durations of current and past statin exposure to high potency or low potency statins were estimated using conditional logistic regression. Ratios were adjusted for confounding by high dimensional propensity scores. Meta-analytic methods estimated overall effects across participating sites., Setting: Seven Canadian provinces and two databases in the United Kingdom and the United States., Participants: 2,067,639 patients aged 40 years or older and newly treated with statins between 1 January 1997 and 30 April 2008. Each person hospitalized for acute kidney injury was matched with ten controls., Intervention: A dispensing event was new if no cholesterol lowering drug or niacin prescription was dispensed in the previous year. High potency statin treatment was defined as ≥ 10 mg rosuvastatin, ≥ 20 mg atorvastatin, and ≥ 40 mg simvastatin; all other statin treatments were defined as low potency. Statin potency groups were further divided into cohorts with or without chronic kidney disease., Main Outcome Measure: Relative hospitalization rates for acute kidney injury., Results: Of more than two million statin users (2,008,003 with non-chronic kidney disease; 59,636 with chronic kidney disease), patients with similar propensity scores were comparable on measured characteristics. Within 120 days of current treatment, there were 4691 hospitalizations for acute kidney injury in patients with non-chronic kidney injury, and 1896 hospitalizations in those with chronic kidney injury. In patients with non-chronic kidney disease, current users of high potency statins were 34% more likely to be hospitalized with acute kidney injury within 120 days after starting treatment (fixed effect rate ratio 1.34, 95% confidence interval 1.25 to 1.43). Users of high potency statins with chronic kidney disease did not have as large an increase in admission rate (1.10, 0.99 to 1.23). χ(2) tests for heterogeneity confirmed that the observed association was robust across participating sites., Conclusions: Use of high potency statins is associated with an increased rate of diagnosis for acute kidney injury in hospital admissions compared with low potency statins. The effect seems to be strongest in the first 120 days after initiation of statin treatment.

In the past two decades, a substantial increase in the incidence of acute kidney injury (AKI) and kidney injury requiring dialysis has occurred in North America. This increase has coincided with an increase in the incidence of end-stage renal disease (ESRD), which has exceeded that expected based upon the prevalence of chronic kidney disease (CKD). In order to better understand the association between these conditions, there has been a proliferation of studies that have examined the risks of incident and progressive CKD following AKI. Animal studies have shown that failed differentiation of epithelial cells following renal ischaemia-reperfusion injury might lead to tubulointerstitial fibrosis, supporting a biological mechanism linking AKI and CKD. Strong and consistent associations between AKI and incident CKD, progression of CKD and incident ESRD have also been shown in epidemiological studies. In this Review, we summarize the wealth of available data on the relationship between AKI and CKD, and discuss the implications of these findings for the long-term clinical management of patients following AKI. We also identify areas of active investigation and future directions for research.

Purpose: The optimal timing for starting renal replacement therapy (RRT) in patients with acute kidney injury (AKI) is unknown. Defining current practice is necessary to design interventional trials. We describe the current Canadian practice regarding the timing of RRT initiation for AKI., Methods: An observational study of patients undergoing RRT for AKI was undertaken at 11 intensive care units (ICUs) across Canada. Data were captured on demographics, clinical and laboratory findings, indications for RRT, and timing of RRT initiation., Results: Among 119 consecutive patients, the most common ICU admission diagnosis was sepsis/septic shock, occurring in 54%. At the time of RRT initiation, the median and interquartile range (IQR) serum creatinine level was 322 (221-432) μmol·L(-1). The mean (SD) values for other parameters were as follows: Sequential Organ Failure Assessment (SOFA) score 13.4 (4.1), pH 7.25 (0.15), potassium 4.6 (1.0) mmol·L(-1). Also, 64% fulfilled the serum creatinine-based criterion for Acute Kidney Injury Network (AKIN) stage 3. Severity of illness, measured using Acute Physiology and Chronic Health Evaluation (APACHE II) and SOFA scores, did not correlate with AKI severity as defined by the serum creatinine-based AKIN criteria. Median (IQR) time from hospital and ICU admission to the start of RRT was 2.0 (1.0-7.0) days and 1.0 (0-2.0) day, respectively., Conclusion: Patients admitted to an ICU who were started on RRT generally had advanced AKI, high-grade illness severity, and multiorgan dysfunction. Also, they were started on RRT shortly after hospital presentation. We describe the current state of practice in Canada regarding the initiation of RRT for AKI in critically ill patients, which can inform the designs of future interventional trials.

Purpose: Our objective was to describe the current practice for initiation of RRT in this population. There is uncertainty regarding the optimal time to initiate renal replacement therapy (RRT) in critically ill patients with acute kidney injury (AKI)., Methods: Prospective study of patients receiving RRT in 6 intensive care units (ICUs) at 3 hospitals from July 2007 to August 2008. We characterized factors associated with start of RRT and evaluated their relationship with mortality., Results: We included 234 patients. RRT was initiated 1 day (0-4) after ICU admission (median [interquartile range]). Median creatinine was 331 μmol/L (225-446 μmol/L), urea 22.9 mmol/L (13.9-32.9 mmol/L), and RIFLE-Failure in 76.9%. Of traditional indications, Pao(2)/Fio(2) < 200 (54.5%) and oliguria (32.9%) were most common. ICU and hospital mortality were 45.3% and 51.9%, respectively. In adjusted analysis, mortality at RRT initiation was associated with creatinine <332 μmol/L (odds ratio [OR] 2.8; 95% confidence interval [CI] 1.5-5.4), change in urea from admission >8.9 mmol/L (OR 1.8; 95% CI, 1.0-3.4), urine output <82 mL/24 hours (OR 3.0; 95% CI, 1.4-6.5), fluid balance >3.0 L/24 hours (OR 2.3; 95% CI, 1.2-4.5), percentage of fluid overload >5% (OR 2.3; 95% CI, 1.2-4.7), 3 or more failing organs (OR 4.5; 95% CI, 1.2-4.2), Sequential Organ Failure Assessment score >14 (OR 2.3; 95% CI, 1.3-4.3), and start 4 days or more after admission (OR 4.3; 95% CI, 1.9-9.5). Mortality was higher as factors accumulated., Conclusion: In ICU patients requiring RRT, there was marked variation in factors that influence start of RRT. RRT initiation with fewer clinical triggers was associated with lower mortality. Timing of RRT may modify survival but requires appraisal in a randomized trial., (Copyright © 2012 Elsevier Inc. All rights reserved.)