Value of Kidney Disease Improving Global Outcomes Urine Output Criteria in Critically Ill Patients: A Secondary Analysis of a Multicenter Prospective Cohort Study

Urine output is an early and strong predictor of acute kidney injury and associated mortality: a systematic literature review of 50 clinical studies

BACKGROUND

Although the present diagnosis of acute kidney injury (AKI) involves measurement of acute increases in serum creatinine (SC) and reduced urine output (UO), measurement of UO is underutilized for diagnosis of AKI in clinical practice. The purpose of this investigation was to conduct a systematic literature review of published studies that evaluate both UO and SC in the detection of AKI to better understand incidence, healthcare resource use, and mortality in relation to these diagnostic measures and how these outcomes may vary by population subtype.

METHODS

The systematic literature review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Data were extracted from comparative studies focused on the diagnostic accuracy of UO and SC, relevant clinical outcomes, and resource usage. Quality and validity were assessed using the National Institute for Health and Care Excellence (NICE) single technology appraisal quality checklist for randomized controlled trials and the Newcastle-Ottawa Quality Assessment Scale for observational studies.

RESULTS

A total of 1729 publications were screened, with 50 studies eligible for inclusion. A majority of studies (76%) used the Kidney Disease: Improving Global Outcomes (KDIGO) criteria to classify AKI and focused on the comparison of UO alone versus SC alone, while few studies analyzed a diagnosis of AKI based on the presence of both UO and SC, or the presence of at least one of UO or SC indicators. Of the included studies, 33% analyzed patients treated for cardiovascular diseases and 30% analyzed patients treated in a general intensive care unit. The use of UO criteria was more often associated with increased incidence of AKI (36%), than was the application of SC criteria (21%), which was consistent across the subgroup analyses performed. Furthermore, the use of UO criteria was associated with an earlier diagnosis of AKI (2.4-46.0 h). Both diagnostic modalities accurately predicted risk of AKI-related mortality.

CONCLUSIONS

Evidence suggests that the inclusion of UO criteria provides substantial diagnostic and prognostic value to the detection of AKI.

Identification of an optimal threshold to define oliguria in critically ill patients: an observational study

BACKGROUND

The relevance of current consensus threshold to define oliguria has been challenged by small observational studies. We aimed to determine the optimal threshold to define oliguria in critically-ill patients.

METHODS

Cohort study including adult patients admitted within a multi-disciplinary intensive care unit between January 1st 2010 and June 15th 2020. Patients on chronic dialysis or who declined consent were excluded. We extracted hourly urinary output (UO) measurements along with patient's characteristics from electronic medical records and 90-day mortality from the Swiss national death registry. We randomly split our data into a training (80%) and a validation (20%) set. In the training set, we developed multivariable models to assess the relationship between 90-day mortality and the minimum average UO calculated over time windows of 3, 6, 12 and 24 h. Optimal thresholds were determined by visually identifying cut-off values for the minimum average UO below which predicted mortality increased substantially. We tested models' discrimination and calibration on the entire validation set as well as on a subset of patients with oliguria according to proposed thresholds.

RESULTS

Among the 15,500 patients included in this analysis (training set: 12,440, validation set: 3110), 73.0% (95% CI [72.3-73.8]) presented an episode of oliguria as defined by consensus criteria (UO < 0.5 ml/kg/h for 6 h). Our models had excellent (AUC > 85% for all time windows) discrimination and calibration. The relationship between minimum average UO and predicted 90-day mortality was nonlinear with an inflexion point at 0.2 ml/kg/h for 3 and 6 h windows and 0.3 ml/kg/h for 12 and 24 h windows. Considering a threshold of < 0.2 ml/kg/h over 6 h, the proportion of patients with an episode of oliguria decreased substantially to 24.7% (95% CI [24.0-25.4]). Contrary to consensus definition, this threshold identified a population with a higher predicted 90-day mortality.

CONCLUSIONS

The widely used cut-off for oliguria of 0.5 ml/kg/h over 6 h may be too conservative. A cut-off of 0.2 ml/kg/h over 3 or 6 h is supported by the data and should be considered in further definitions of oliguria.

Impact of Different KDIGO Criteria on Clinical Outcomes for Early Identification of Acute Kidney Injury after Non-Cardiac Surgery

The Kidney Disease Improving Global Outcomes (KDIGO) guidelines are currently used in acute kidney injury (AKI) diagnosis and include both serum creatinine (SCR) and urine output (UO) criteria. Currently, many AKI-related studies have inconsistently defined AKI, which possibly affects the comparison of their results. Therefore, we hypothesized that the different criteria in the KDIGO guidelines vary in measuring the incidence of AKI and its association with clinical outcomes. We retrospectively analyzed that data of patients admitted to the intensive care unit after non-cardiac surgery in 2019. Three different criteria used to define AKI were included: UOmean, mean UO < 0.5 mL/kg/h over time; UOcont, hourly UO < 0.5 mL/kg/h over time; or SCR, KDIGO guidelines SCR criteria. A total of 777 patients were included, and the incidence of UOmean-AKI was 33.1%, the incidence of UOcont-AKI was 7.9%, and the incidence of SCR-AKI was 2.0%. There were differences in the length of ICU stay and hospital stay between AKI and non-AKI patients under different criteria. We found differences in the incidence and clinical outcomes of AKI after non-cardiac surgery when using different KDIGO criteria.

Survival and recovery modeling of acute kidney injury in critically ill adults

Objectives:

Acute kidney injury is common among the critically ill. However, the incidence, medication use, and outcomes of acute kidney injury have been variably described. We conducted a single-center, retrospective cohort study to examine the risk factors and correlates associated with acute kidney injury in critically ill adults with a particular focus on medication class usage.

Methods:

We reviewed the electronic medical records of all adult patients admitted to an intensive care unit between 1 February and 30 August 2020. Acute kidney injury was defined by the 2012 Kidney Disease: Improving Global Outcomes guidelines. Data included were demographics, comorbidities, symptoms, laboratory parameters, interventions, and outcomes. The primary outcome was acute kidney injury incidence. A Least Absolute Shrinkage and Selection Operator regression model was used to determine risk factors associated with acute kidney injury. Secondary outcomes including acute kidney injury recovery and intensive care unit mortality were analyzed using a Cox regression model.

Results:

Among 226 admitted patients, 108 (47.8%) experienced acute kidney injury. 37 (34.3%), 39 (36.1%), and 32 patients (29.6%) were classified as acute kidney injury stages I–III, respectively. Among the recovery and mortality cohorts, analgesics/sedatives, anti-infectives, and intravenous fluids were significant (p-value < 0.05). The medication classes IV-fluid electrolytes nutrition (96.7%), gastrointestinal (90.2%), and anti-infectives (81.5%) were associated with an increased odds of developing acute kidney injury, odd ratios: 1.27, 1.71, and 1.70, respectively. Cox regression analyses revealed a significantly increased time-varying mortality risk for acute kidney injury-stage III, hazard ratio: 4.72 (95% confidence interval: 1–22.33). In the recovery cohort, time to acute kidney injury recovery was significantly faster in stage I, hazard ratio: 9.14 (95% confidence interval: 2.14–39.06) cohort when compared to the stage III cohort.

Conclusion:

Evaluation of vital signs, laboratory, and medication use data may be useful to determine acute kidney injury risk stratification. The influence of particular medication classes further impacts the risk of developing acute kidney injury, necessitating the importance of examining pharmacotherapeutic regimens for early recognition of renal impairment and prevention.

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

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

Utilizing reclassification to explore characteristics and prognosis of KDIGOSCr AKI subgroups: a retrospective analysis of a multicenter prospective cohort study

BACKGROUND

Acute kidney injury (AKI) is widespread in the intensive care unit (ICU) and affects patient prognosis. According to Kidney Disease: Improving Global Outcomes (KDIGO) guidelines, the absolute and relative increases of serum creatinine (Scr) are classified into the same stage. Whether the prognosis of the two types of patients is similar in the ICU remains unclear.

METHODS

According to the absolute and relative increase of Scr, AKI stage 1 and stage 3 patients were divided into stage 1a and 1b, stage 3a and 3b groups, respectively. Their demographics, laboratory results, clinical characteristics, and outcomes were analyzed retrospectively.

RESULTS

Of the 345 eligible cases, we analyzed stage 1 because stage 3a group had only one patient. Using 53 or 61.88 µmol/L as the reference Scr (Scr_ref), no significant differences were observed in ICU mortality (P₅₃=0.076, P_61.88=0.070) or renal replacement therapy (RRT) ratio, (P₅₃=0.356, P_61.88=0.471) between stage 1a and 1b, but stage 1b had longer ICU length of stay (LOS) than stage 1a (P₅₃<0.001, P_61.88=0.032). In the Kaplan-Meier survival analysis, no differences were observed in ICU mortality between stage 1a and 1b (P₅₃=0.378, P_61.88=0.255). In a multivariate analysis, respiratory failure [HR = 4.462 (95% CI 1.144-17.401), p = 0.031] and vasoactive drug therapy [HR = 4.023 (95% CI 1.584-10.216), p = 0.003] were found to be independently associated with increased risk of death.

CONCLUSION

ICU LOS benefit was more prominent in KDIGO_SCr AKI stage 1a patients than in stage 1 b. Further prospective studies with a larger sample size are necessary to confirm the effectiveness of reclassification.

Association of Oliguria With Acute Kidney Injury Diagnosis, Severity Assessment, and Mortality Among Patients With Critical Illness

Importance

The current definition and staging of acute kidney injury (AKI) considers alterations in serum creatinine (sCr) level and urinary output (UO). However, the relevance of oliguria-based criteria is disputed.

Objective

To determine the contribution of oliguria, as defined by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria, to AKI diagnosis, severity assessment, and short- and long-term outcomes.

Design, Setting, and Participants

This cohort study included adult patients admitted to a multidisciplinary intensive care unit from January 1, 2010, to June 15, 2020. Patients receiving long-term dialysis and those who declined consent were excluded. Daily sCr level and hourly UO measurements along with sociodemographic characteristics and severity scores were extracted from electronic medical records. Long-term mortality was assessed by cross-referencing the database with the Swiss national death registry. The onset and severity of AKI according to the KDIGO classification was determined using UO and sCr criteria separately, and their agreement was assessed.

Main Outcomes and Measures

Using a multivariable model accounting for baseline characteristics, severity scores, and sCr stages, the association of UO criteria with 90-day mortality was evaluated. Sensitivity analyses were conducted to assess how missing sCr, body weight, and UO values, as well as different sCr baseline definitions and imputations methods, would affect the main results.

Results

Among the 15 620 patients included in the study (10 330 men [66.1%] with a median age of 65 [IQR, 53-75] years, a median Simplified Acute Physiology Score II score of 40.0 [IQR, 30.0-53.0], and a median follow-up of 67.0 [IQR, 34.0-100.0] months), 12 143 (77.7%) fulfilled AKI criteria. Serum creatinine and UO criteria had poor agreement on AKI diagnosis and staging (Cohen weighted κ, 0.36; 95% CI, 0.35-0.37; P < .001). Compared with the isolated use of sCr criteria, consideration of UO criteria enabled identification of AKI in 5630 patients (36.0%). Those patients had a higher 90-day mortality than patients without AKI (724 of 5608 [12.9%] vs 288 of 3462 [8.3%]; P < .001). On multivariable analysis accounting for sCr stage, comorbidities, and illness severity, UO stages 2 and 3 were associated with a higher 90-day mortality (odds ratios, 2.4 [95% CI, 1.6-3.8; P < .001] and 6.2 [95% CI, 3.7-10.5; P < .001], respectively). These results remained significant in all sensitivity analyses.

Conclusions and Relevance

The findings of this cohort study suggest that oliguria lasting more than 12 hours (KDIGO stage 2 or 3) has major AKI diagnostic implications and is associated with outcomes irrespective of sCr elevations.

Relationship between acute kidney injury and mortality in poisoning - a systematic review and metanalysis

RATIONALE

Three consensus classifications of acute kidney injury have been published. These are RIFLE (Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease published by the Acute Dialysis Quality Initiative workgroup), AKIN (published by the Acute Kidney Injury Network) and KDIGO (published by the Kidney Disease Improving Global Outcome workgroup). Acute kidney injury has been reported consistently as associated with worsened outcomes. However, toxicant-related acute kidney injury has been excluded from the studies used to validate the classifications of acute kidney injury.

OBJECTIVE

To study whether poisoned patients who develop acute kidney injury, as defined by consensus definitions/classifications, have higher mortality compared to those who did not.

METHODS

Databases were searched from 2004 to 2019 using the following keywords (KDIGO OR "Kidney Disease: Improving Global Outcomes" OR "Kidney Disease Improving Global Outcomes" OR AKIN OR "AKI network" OR "Acute kidney Injury Network" OR ADQI OR RIFLE OR "Acute dialysis quality initiative") AND (intoxication OR poisoning OR overdose OR ingestion) AND (AKI OR kidney OR renal OR ARF). If data were available, we used a random-effects meta-analysis model and Fisher's exact test to compare mortality in patients according to kidney function definitions (acute kidney injury vs not) and stages (stages vs no acute kidney injury), respectively. If data were available, we assessed the correlation between mortality and renal function (no acute kidney injury, risk/stage 1, injury/stage 2 and failure/stage 3) using the Spearman correlation. If available, we collected the results of statistical analyses in studies that have used acute kidney injury to predict mortality.

RESULTS

Study selection. Thirty-three relevant studies were found, 22/33 retrospective studies (67%) and 11/33 prospective studies (33%). Paraquat was the most frequent toxicant involved (13/33, 39%). We found a disparity between studies regarding the timeframe during which mortality was assessed, the temporality of the renal function considered to predict mortality (initial/worst) and the criteria used to define/grade acute kidney injury across studies. Univariate association between acute kidney injury definitions/stages and mortality. Consensus definitions/staging of acute kidney injury were associated with higher mortality, using univariate analyses, in twenty-eight (RIFLE = 7; AKIN = 12; KDIGO = 9) studies included but not in five (AKIN = 4, KDIGO = 1). When available data were pooled, RIFLE (5 studies), AKIN (16 studies) and KDIGO definitions (8 studies) of acute kidney injury were associated with a higher mortality (Log unadjusted Odds ratios [95%-confidence interval], 2.60 [2.23; 2.97], 2.02 [1.48; 2,52] and 3.22 [2,65; 3.78], respectively). However, we found high heterogeneity (I²=54,7%) and publication bias among studies using AKIN. In ten studies with available data, the correlation between renal function (no acute kidney injury, risk/stage 1, injury/stage 2, failure/stage 3) and mortality was significant in 5 studies (RIFLE = 2; AKIN = 3), but not in five studies (RIFLE = 1; AKIN = 3; KDIGO = 1).Multivariate association between acute kidney injury definitions/stages and mortality. The definitions of acute kidney injury were associated with higher mortality in two studies (RIFLE = 2), but not in four studies (AKIN = 1 and KDIGO = 3. The stages of acute kidney injury (including one or more stages) were associated with higher mortality in four (RIFLE = 1, AKIN = 1 and KDIGO = 2).

CONCLUSIONS

All three consensus definitions/classifications were associated independently with increased mortality in poisoning but with disparity between studies reporting acute kidney injury.

End-of-Procedure Volume Responsiveness Defined by the Passive Leg Raise Test Is Not Associated With Acute Kidney Injury After Cardiopulmonary Bypass

OBJECTIVES

Renal hypoperfusion is a common mechanism of cardiac surgery-related acute kidney injury (CS-AKI). However, the optimal amount of volume resuscitation to correct systemic hypoperfusion and prevent the postoperative development of CS-AKI has been a subject of debate. The goal of this study was to assess the association of volume responsiveness determined by stroke volume variation using the passive leg raise test (PLRT) at chest closure, with the development of CS-AKI according to the Kidney Disease Improving Global Outcomes criteria.

DESIGN

Single-center, prospective observational study.

SETTING

Tertiary hospital.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 131 patients were studied from January 2015 until May 2017. All patients underwent cardiac surgery that required cardiopulmonary bypass. Volume responsiveness was assessed at chest closure using the PRLT. Stroke volume variation from the sitting to the recumbent positions was measured by transesophageal echocardiography. Fluid responsiveness was defined as an increase of >12% of stroke volume from sitting to recumbent positions. A total of 82 (68.3%) patients were fluid-responsive versus 38 (31.6%) who were fluid-unresponsive. CS-AKI occurred in 30% of patients. There was no difference in CS-AKI between fluid-responsive and fluid-nonresponsive groups. However, CS-AKI was associated independently with an increases in body mass index and preoperative diastolic blood pressure. CS-AKI also was associated with prolonged intensive care unit length of stay.

CONCLUSION

End-of-procedure volume responsiveness is not associated with a high risk for postoperative CS-AKI.

Acute Kidney Injury in Asia: Disease Burden

Acute kidney injury (AKI) is a common and critical clinical disorder with non-negligible morbidity and mortality and remains a large public health problem. Asia, as the world's largest and most populous continent, is crucial in eliminating unsatisfactory outcomes of AKI. The diversities in climate, customs, and economic status lead to various clinical features of AKI across Asia. In this review, we focus on the epidemiologic data and clinical features of AKI in different Asian countries and clinical settings, and we show the huge medical and economic burden of AKI in Asian countries. Drugs and sepsis are the most common etiologies for AKI, however, an adequate surveillance system has not been well established. There is significant undertreatment of AKI in many regions, and medical resources for renal replacement therapy are not universally available. Although substantial improvement has been achieved, health care for AKI still needs improvement, especially in developing regions.

Pathogenesis and Management of Acute Kidney Injury in Patients with Nephrotic Syndrome Due to Primary Glomerulopathies

Acute kidney injury in the context of nephrotic syndrome is a serious and alarming clinical problem. Largely, acute kidney injury is a relatively frequent complication among patients with comorbidities while it has been independently associated with an increased risk of adverse outcomes, including death and chronic kidney disease. Nephrotic syndrome, without hematuria or with minimal hematuria, includes a list of certain glomerulopathies; minimal change disease, focal segmental glomerulosclerosis and membranous nephropathy. In the light of primary nephrotic syndrome, pathophysiology of acute kidney injury is differentiated by the nature of the primary disease and the severity of the nephrotic state. This review aims to explore the clinical circumstances and pathogenetic mechanisms of acute kidney injury in patients with nephrotic syndrome due to primary glomerulopathies, focusing on newer perceptions regarding the pathogenesis and management of this complicated condition, for the prompt recognition and timely initiation of appropriate treatment in order to restore renal function to its baseline level. Prompt recognition of the precise cause of acute kidney injury is crucial for renal recovery. Clinical characteristics, laboratory and serological findings along with histopathological findings, if required, will reveal the implicated pathway leading to individualized approach and management.

Dynamic Change of Red Cell Distribution Width Levels in Prediction of Hospital Mortality in Chinese Elderly Patients with Septic Shock

Background:

The normal range of red cell distribution width (RDW) level is <15%. Several studies have indicated that a high RDW level was associated with mortality in critically ill patients, and the patients with a high RDW level need increased focus in clinical practice. In view of the difficulty in defining the specific value of high RDW level, the key is to focus on the patient with the level beyond the normal upper limit. This study aimed to determine whether dynamic change of RDW levels, rather than the level itself, is predictive of death in elderly patients with septic shock when RDW level is beyond 15%.

Methods:

Between September 2013 and September 2015, the elderly septic shock patients with RDW level beyond 15% were enrolled in this study. The RDW levels were measured at enrollment (day 1), and days 4 and 7 after enrollment. Sequential Organ Failure Assessment (SOFA) scores were recorded simultaneously.

Results:

A total of 45 patients, including 32 males and 13 females, were included in the final analysis. Based on their hospital outcomes, these patients were divided into the survivor group (n = 26) and the nonsurvivor group (n = 19). There were no significant differences in age, gender, body mass index, initial level of RDW, Acute Physiology and Chronic Health Evaluation II scores, and SOFA scores between survivors and nonsurvivors. At days 4 and 7 measurement, both RDW level (median [interquartile range]: day 4: 15.8 [2.0]% vs. 16.7 [2.0]%, P = 0.011; and day 7: 15.6 [1.8]% vs. 17.7 [2.5]%, P = 0.001) and SOFA scores (day 4: 7.0 [4.0] vs. 16.0 [5.0], P < 0.001, day 7: 5.5 [4.0] vs. 17.0 [5.0], P < 0.001) were significantly lower in survivors than those in nonsurvivors. Dynamic changes of RDW and SOFA scores in survivor group were significantly different from those in nonsurvivor group (all P < 0.05). Continuous increase in RDW level was observed in 10 of the 13 nonsurvivors, but only in 3 of the 26 survivors. The level of RDW7 and dynamic changes significantly correlated with their counterparts of SOFA scores (all P < 0.05), whereas the levels of RDW1 and RDW4 had no significant correlation with their counterparts of SOFA scores (all P > 0.05).

Conclusions:

Continuous increase in RDW level, rather than the level of RDW itself, was more useful in predicting hospital death in elderly patients with septic shock when the level of RDW was >15%. The dynamic changes of RDW were highly correlated with the SOFA score in the patients.

The Role of Oliguria and the Absence of Fluid Administration and Balance Information in Illness Severity Scores

Urinary examination has formed part of patient assessment since the earliest days of medicine. Current definitions of oliguria are essentially arbitrary, but duration and intensity of oliguria have been associated with an increased risk of mortality, and this risk is not completely attributable to the development of concomitant acute kidney injury (AKI) as defined by changes in serum creatinine concentration. The increased risk of death associated with the development of AKI itself may be modified by directly or indirectly by progressive fluid accumulation, due to reduced elimination and increased fluid administration. None of the currently extant major illness severity scoring systems or outcome prediction models use modern definitions of AKI or oliguria, or any values representative of fluid volumes variables. Even if a direct relationship with mortality is not observed, then it is possible that fluid balance or fluid volume variables mediate the relationship between illness severity and mortality in the renal and respiratory physiological domains. Fluid administration and fluid balance may then be an important, easily modifiable therapeutic target for future investigation. These relationships require exploration in large datasets before being prospectively validated in groups of critically ill patients from differing jurisdictions to improve prognostication and mortality prediction.