Novel risk factors for acute kidney injury:

Prediction of acute kidney injury in patients with liver cirrhosis using machine learning models: evidence from the MIMIC-III and MIMIC-IV

PURPOSE

To develop and validate a machine learning (ML)-based prediction model for acute kidney injury (AKI) in patients with liver cirrhosis.

METHODS

Data on liver cirrhosis patients were extracted from the Medical Information Mart for Intensive Care III (MIMIC-III) and MIMIC-IV databases in this retrospective cohort study. ML algorithms, including random forest (RF), extreme gradient boosting (XGB), light gradient boosting machine (LGBM), and gradient boosting decision tree (GBDT) were applied to construct prediction models. Predictors were screened via univariate logistic regression, and then the models were developed with all data of the included patients. A bootstrap resampling method was adopted to validate the models. The predictive abilities of our final model were compared with those of the sequential organ failure assessment score (SOFA), simplified acute physiology score II (SAPS II), Model for End-stage Liver Disease (MELD), and MELD Na.

RESULTS

This study included 950 patients, of which 429 (45.16%) had AKI. Mechanical ventilation, vasopressor, international normalized ratio (INR), bilirubin, Charlson comorbidity index (CCI), prothrombin time (PT), estimated glomerular filtration rate (EGFR), partial thromboplastin time (PTT), and heart rate served as predictors. In the derivation set, the developed RF [area under curve (AUC) = 0.747], XGB (AUC = 0.832), LGBM (AUC = 0.785), and GBDT (AUC = 0.811) models exhibited significantly greater predictive performance than the logistic regression model (AUC = 0.699) (all P < 0.05). Among the ML-based models, the XGB model had the greatest AUC. In internal validation, the predictive capacity of the XGB model (AUC = 0.833) was significantly superior to that of the logistic regression model (AUC = 0.701) (P = 0.045). Hence, the XGB model was selected as the final model for AKI prediction. In contrast to the XGB model (AUC = 0.832), the SOFA (AUC = 0.609), MELD (AUC = 0.690), MELD Na (AUC = 0.690), and SAPS II (AUC = 0.641) had significantly lower predictive abilities in the derivation set (all P < 0.001). The XGB model was internally validated to have an AUC of 0.833, which was significantly higher than the SOFA (AUC = 0.609), MELD (AUC = 0.690), MELD Na (AUC = 0.688), and SAPS II (AUC = 0.641) (all P < 0.05).

CONCLUSION

The XGB model had a better performance than the logistic regression model, SOFA, MELD, MELD Na, and SAPS II in AKI prediction for cirrhosis patients, which may help identify patients at a risk of AKI, and then provide timely interventions.

Acute Kidney Injury: Definition, Management, and Promising Therapeutic Target

Acute kidney injury (AKI) is caused by a sudden loss of renal function, resulting in the build-up of waste products and a significant increase in mortality and morbidity. It is commonly diagnosed in critically ill patients, with its occurrence estimated at up to 50% in patients hospitalized in the intensive critical unit. Despite ongoing efforts, the death rate associated with AKI has remained high over the past half-century. Thus, it is critical to investigate novel therapy options for preventing the epidemic. Many studies have found that inflammation and Toll-like receptor-4 (TLR-4) activation have a significant role in the pathogenesis of AKI. Noteworthy, challenges in the search for efficient pharmacological therapy for AKI have arisen due to the multifaceted origin and complexity of the clinical history of people with the disease. This article focuses on kidney injury's epidemiology, risk factors, and pathophysiological processes. Specifically, it focuses on the role of TLRs especially type 4 in disease development.

Development and Validation of a Prediction Model for Acute Kidney Injury Among Patients With Acute Decompensated Heart Failure

Background: Acute kidney injury is an adverse event that carries significant morbidity among patients with acute decompensated heart failure (ADHF). We planned to develop a parsimonious model that is simple enough to use in clinical practice to predict the risk of acute kidney injury (AKI) occurrence. Methods: Six hundred and fifty patients with ADHF were enrolled in this study. Data for each patient were collected from medical records. We took three different approaches of variable selection to derive four multivariable logistic regression model. We selected six candidate predictors that led to a relatively stable outcome in different models to derive the final prediction model. The prediction model was verified through the use of the C-Statistics and calibration curve. Results: Acute kidney injury occurred in 42.8% of the patients. Advanced age, diabetes, previous renal dysfunction, high baseline creatinine, high B-type natriuretic peptide, and hypoalbuminemia were the strongest predictors for AKI. The prediction model showed moderate discrimination C-Statistics: 0.766 (95% CI, 0.729-0.803) and good identical calibration. Conclusion: In this study, we developed a prediction model and nomogram to estimate the risk of AKI among patients with ADHF. It may help clinical physicians detect AKI and manage it promptly.

Rasburicase improves the outcome of acute kidney injury from typical hemolytic uremic syndrome

BACKGROUND

Typical hemolytic uremic syndrome (HUS) causes acute kidney injury (AKI) and serious sequelae of chronic kidney disease (CKD) in some. Hyperuricemia is a common finding in typical HUS that may contribute to kidney damage. We explored whether aggressive management of hyperuricemia with rasburicase could improve outcomes in AKI patients with typical HUS.

METHODS

We retrospectively analyzed medical records of children with typical HUS admitted to a tertiary center between 2005 and 2017. We compared clinical outcomes of hospitalization and 1-year post-discharge between those with rasburicase treatment (n = 13) and those without (controls, n = 29).

RESULTS

With rasburicase treatment, hyperuricemia corrected more rapidly (median 36 vs. 120 h, p < 0.001), and hospital stays were shorter (median 9 vs. 12 days, p = 0.003) than in the controls. There was no difference in dialysis requirement. At 1-year post-discharge, the proportion of patients with impaired kidney function (estimated glomerular filtration rate < 90 mL/min/1.73 m²) was lower in the rasburicase group (7.7% vs. 41.4%, p = 0.036) than in the controls. Hypertension and proteinuria tended to be more common in the controls than in the rasburicase group. Collectively, long-term renal sequelae of impaired kidney function, proteinuria, or hypertension at a 1-year follow-up was less common in the rasburicase group than in the controls (7.7% vs. 62.1%; p = 0.001).

CONCLUSIONS

Children with typical HUS treated with rasburicase had shorter hospital stays and less long-term sequelae at 1-year post-discharge than those who were not treated with rasburicase. These results support the use of rasburicase to prevent CKD in pediatric patients with typical HUS-associated AKI. Graphical Abstract.

Clinical Characteristics of Hospitalized Patients with Drug-Induced Acute Kidney Injury and Associated Risk Factors: A Case-Control Study

Background

Drug-induced acute kidney injury (D-AKI) is increasingly common and can extend the hospital length of stay and increase mortality. This study is aimed at analyzing the clinical characteristics of hospitalized patients with D-AKI and the associated risk factors in a multidrug environment.

Methods

A retrospective study among hospitalized patients was conducted in July 2019 based on the Adverse Drug Events Active Surveillance and Assessment System-2 developed by the authors. Four controls were matched with each case according to the matching criteria. The risk factors for D-AKI were identified by binary multivariate logistic regression.

Results

A total of 23,073 patients were hospitalized in July 2019, 21,131 of whom satisfied the inclusion criteria. The independent risk factors for D-AKI consisted of alcohol abuse (odds ratio (OR), 2.05; 95% confidence interval (CI), 1.04-4.07), nonsteroidal anti-inflammatory drug (NSAID) use (OR, 2.39; 95% CI, 1.25-4.58), diuretic use (OR, 2.64; 95% CI, 1.42-4.92), prior anemia (OR, 4.10; 95% CI, 1.94-8.67), and prior chronic kidney disease (OR, 2.33; 95% CI, 1.07-5.08).

Conclusions

The occurrence of D-AKI in hospitalized patients had significant associations with alcohol abuse, combination therapy with NSAIDs or diuretics, and prior anemia or chronic kidney disease. Clinicians should meticulously follow patients with the above characteristics.

A prospective study of acute kidney injury in the intensive care unit: development and validation of a risk prediction model

BACKGROUND

Acute kidney injury (AKI) has high morbidity and mortality in intensive care units (ICU). It can also lead to chronic kidney disease (CKD), more costs and longer hospital stay. Early identification of AKI is important.

METHODS

We conducted this monocenter prospective observational study at West China Hospital, Sichuan University, China. We recorded information of each patient in the ICU within 24 h after admission and updated every two days. Patients who reached the primary outcome were accepted into the AKI group. Of all patients, we randomly drew 70% as the development cohort and the remaining 30% as the validation cohort. Using binary logistic regression we got a risk prediction model of the development cohort. In the validation cohort, we validated its discrimination by the area under the receiver operator curve (AUROC) and calibration by a calibration curve.

RESULTS

There were 656 patients in the development cohorts and 280 in the validation cohort. Independent predictors of AKI in the risk prediction model including hypertension, chronic kidney disease, acute pancreatitis, cardiac failure, shock, pH ≤ 7.30, CK > 1000 U/L, hypoproteinemia, nephrotoxin exposure, and male. In the validation cohort, the AUROC is 0.783 (95% CI 0.730-0.836) and the calibration curve shows good calibration of this prediction model. The optimal cut-off value to distinguish high-risk and low-risk patients is 4.5 points (sensitivity is 78.4%, specificity is 73.2% and Youden's index is 0.516).

CONCLUSIONS

This risk prediction model can help to identify high-risk patients of AKI in ICU to prevent the development of AKI and treat it at the early stages. Trial registration TCTR, TCTR20170531001. Registered 30 May 2017, http://www.clinicaltrials.in.th/index.php?tp=regtrials&menu=trialsearch&smenu=fulltext&task=search&task2=view1&id=2573.

Feature Ranking in Predictive Models for Hospital-Acquired Acute Kidney Injury

Acute Kidney Injury (AKI) is a common complication encountered among hospitalized patients, imposing significantly increased cost, morbidity, and mortality. Early prediction of AKI has profound clinical implications because currently no treatment exists for AKI once it develops. Feature selection (FS) is an essential process for building accurate and interpretable prediction models, but to our best knowledge no study has investigated the robustness and applicability of such selection process for AKI. In this study, we compared eight widely-applied FS methods for AKI prediction using nine-years of electronic medical records (EMR) and examined heterogeneity in feature rankings produced by the methods. FS methods were compared in terms of stability with respect to data sampling variation, similarity between selection results, and AKI prediction performance. Prediction accuracy did not intrinsically guarantee the feature ranking stability. Across different FS methods, the prediction performance did not change significantly, while the importance rankings of features were quite different. A positive correlation was observed between the complexity of suitable FS method and sample size. This study provides several practical implications, including recognizing the importance of feature stability as it is desirable for model reproducibility, identifying important AKI risk factors for further investigation, and facilitating early prediction of AKI.

Risk indicators for acute kidney injury in cardiogenic shock

PURPOSE

In critical illness, the relation between the macrocirculation, microcirculation and organ dysfunction, such as acute kidney injury (AKI), is complex. This study aimed at identifying predictors for AKI in patients with cardiogenic shock.

MATERIALS AND METHODS

Thirty-nine adult cardiogenic shock patients, with an admission creatinine <200 μmol l^-1, and whose microcirculation was measured within 48 h were enrolled. Patient data were analyzed if AKI stage ≥1 developed according to the Kidney Disease/Improving Outcomes classification within 48 h after admission. Variables with a p < .05 in the univariate analysis were considered for analysis with logistic regression.

RESULTS

Twenty-four patients (61.5%) developed AKI within 48 h. The group that developed AKI had higher central venous pressures (CVP), lower diastolic arterial blood pressures and mean perfusion pressures, higher maximum ventilator pressures as well as positive end expiratory pressures and were treated with higher dosages of dobutamine. There was no difference of the microcirculation. In the multivariate logistic regression analysis, CVP was the only independent predictor for AKI (OR 1.241; 95% CI 1.030-1.495; p = .023).

CONCLUSIONS

In this population of patients with cardiogenic shock, CVP was associated with the development of AKI.

Update on perioperative acute kidney injury

PURPOSE OF REVIEW

In this review, we discuss the latest updates on perioperative acute kidney injury (AKI) and the specific considerations that are relevant to different surgeries and patient populations.

RECENT FINDINGS

AKI diagnosis is constantly evolving. New biomarkers detect AKI early and shed a light on the possible cause of AKI. Hypotension, even for a short duration, is associated with perioperative AKI. The debate on the deleterious effects of chloride-rich solutions is still far from conclusion. Remote ischemic preconditioning is showing promising results in the possible prevention of perioperative AKI. No definite data show a beneficiary effect of statins, fenoldepam, or sodium bicarbonate in preventing AKI.

SUMMARY

Perioperative AKI is prevalent and associated with significant morbidity and mortality. Considering the lack of effective preventive or therapeutic interventions, this review focuses on perioperative AKI: measures for early diagnosis, defining risks and possible mechanisms, and summarizing current knowledge for intraoperative fluid and hemodynamic management to reduce risk of AKI.

Low, rather than High, Body Mass Index Is a Risk Factor for Acute Kidney Injury in Multiethnic Asian Patients: A Retrospective Observational Study

Background

Acute kidney injury (AKI) is common in hospitalised patients. The relationship between body mass index (BMI) and the risk of having AKI for patients in the acute hospital setting is not known, particularly in the Asian population.

Methods

This was a retrospective, single-centre, observational study conducted in Singapore, a multiethnic population. All patients aged ≥21 years and hospitalised from January to December 2013 were recruited.

Results

A total of 12,555 patients were eligible for the analysis. A BMI of <18.5 kg/m² was independently associated with the development of AKI in hospitalised patients (odds ratio (OR): 1.23 [95% confidence interval [CI]: 1.04–1.44, P = 0.01]) but not for overweight and obesity. Subgroup analysis further revealed that underweight patients aged ≥75 and repeated hospitalisation posed a higher risk of AKI (OR: 1.25 [CI: 1.01–1.56], P = 0.04; OR: 1.23 [CI: 1.04–1.44], P = 0.01, resp.). Analyses by interactions between different age groups and BMI using continuous or categorised variables did not affect the overall probability of developing AKI.

Conclusions

Underweight Asian patients are susceptible to AKI in acute hospital settings. Identification of this novel risk factor for AKI allows us to optimise patient care by prevention, early detection, and timely intervention.

Risk Factor Analysis for AKI Including Laboratory Indicators: a Nationwide Multicenter Study of Hospitalized Patients

BACKGROUND/AIMS

Risk factor studies for acute kidney injury (AKI) in China are lacking, especially those regarding non-traditional risk factors, such as laboratory indicators.

METHODS

All adult patients admitted to 38 tertiary and 22 secondary hospitals in China in any one month between July and December 2014 were surveyed. AKI patients were screened according to the Kidney Disease: Improving Global Outcomes' definition of AKI. Logistic regression was used to analyze the risk factors for AKI, and Cox regression was used to analyze the risk of in-hospital mortality for AKI patients; additionally, a propensity score analysis was used to reconfirm the risk factors among laboratory indicators for mortality.

RESULTS

The morbidity of AKI was 0.97%. Independent risk factors for AKI were advancing age, male gender, hypertension, and chronic kidney disease. All-cause mortality was 16.5%. The predictors of mortality in AKI patients were advancing age, tumor, higher uric acid level and increases in Acute Physiologic Assessment and Chronic Health Evaluation II and Sequential Organ Failure Assessment scores. The hazard ratio (HR) for mortality with uric acid levels > 9.1 mg/dl compared with ≤ 5.2 mg/dl was 1.78 (95% CI: 1.23 to 2.58) for the AKI patients as a group, and was 1.73 (95% CI: 1.24 to 2.42) for a propensity score-matched set.

CONCLUSION

In addition to traditional risk factors, uric acid level is an independent predictor of all-cause mortality after AKI.

Acute Kidney Injury Risk Assessment: Differences and Similarities Between Resource-Limited and Resource-Rich Countries

The incidence of acute kidney injury (AKI) among acutely ill patients is reportedly very high and has vexing consequences on patient outcomes and health care systems. The risks and impact of AKI differ between developed and developing countries. Among developing countries, AKI occurs in young individuals with no or limited comorbidities, and is usually due to environmental causes, including infectious diseases. Although several risk factors have been identified for AKI in different settings, there is limited information on how risk assessment can be used at population and patient levels to improve care in patients with AKI, particularly in developing countries where significant health disparities may exist. The Acute Disease Quality Initiative consensus conference work group addressed the issue of identifying risk factors for AKI and provided recommendations for developing individualized risk stratification strategies to improve care. We proposed a 5-dimension, evidence-based categorization of AKI risk that allows clinicians and investigators to study, define, and implement individualized risk assessment tools for the region or country where they practice. These dimensions include environmental, socioeconomic and cultural factors, processes of care, exposures, and the inherent risks of AKI. We provide examples of these risks and describe approaches for risk assessments in the developing world. We anticipate that these recommendations will be useful for health care providers to plan and execute interventions to limit the impact of AKI on society and each individual patient. Using a modified Delphi process, this group reached consensus regarding several aspects of AKI risk stratification.

Renoprotection: focus on TRPV1, TRPV4, TRPC6 and TRPM2

Members of the transient receptor potential (TRP) cation channel receptor family have unique sites of regulatory function in the kidney which enables them to promote regional vasodilatation and controlled Ca²⁺ influx into podocytes and tubular cells. Activated TRP vanilloid 1 receptor channels (TRPV1) have been found to elicit renoprotection in rodent models of acute kidney injury following ischaemia/reperfusion. Transient receptor potential cation channel, subfamily C, member 6 (TRPC6) in podocytes is involved in chronic proteinuric kidney disease, particularly in focal segmental glomerulosclerosis (FSGS). TRP vanilloid 4 receptor channels (TRPV4) are highly expressed in the kidney, where they induce Ca²⁺ influx into endothelial and tubular cells. TRP melastatin (TRPM2) non-selective cation channels are expressed in the cytoplasm and intracellular organelles, where their inhibition ameliorates ischaemic renal pathology. Although some of their basic properties have been recently identified, the renovascular role of TRPV1, TRPV4, TRPC6 and TRPM2 channels in disease states such as obesity, hypertension and diabetes is largely unknown. In this review, we discuss recent evidence for TRPV1, TRPV4, TRPC6 and TRPM2 serving as potential targets for acute and chronic renoprotection in chronic vascular and metabolic disease.

Heat strain, volume depletion and kidney function in California agricultural workers

BACKGROUND

Agricultural work can expose workers to increased risk of heat strain and volume depletion due to repeated exposures to high ambient temperatures, arduous physical exertion and limited rehydration. These risk factors may result in acute kidney injury (AKI).

METHODS

We estimated AKI cumulative incidence in a convenience sample of 283 agricultural workers based on elevations of serum creatinine between preshift and postshift blood samples. Heat strain was assessed based on changes in core body temperature and heart rate. Volume depletion was assessed using changes in body mass over the work shift. Logistic regression models were used to estimate the associations of AKI with traditional risk factors (age, diabetes, hypertension and history of kidney disease) as well as with occupational risk factors (years in farm work, method of payment and farm task).

RESULTS

35 participants were characterised with incident AKI over the course of a work shift (12.3%). Workers who experienced heat strain had increased adjusted odds of AKI (1.34, 95% CI 1.04 to 1.74). Piece rate work was associated with 4.24 odds of AKI (95% CI 1.56 to 11.52). Females paid by the piece had 102.81 adjusted odds of AKI (95% CI 7.32 to 1443.20).

DISCUSSION

Heat strain and piece rate work are associated with incident AKI after a single shift of agricultural work, though gender differences exist. Modifications to payment structures may help prevent AKI.

The Kidney: An Organ in the Front Line of Oxidative Stress-Associated Pathologies

Both acute kidney injury (AKI) and chronic kidney disease (CKD) are major causes of renal failure in humans and are associated with high incidences of morbidity and mortality rates. AKI and CKD are closely interconnected, and fueled by the obesity and diabetes epidemic, their prevalence is alarmingly increasing to the point that it currently represents a major heath issue worldwide. The kidney is an organ that is particularly sensitive to redox imbalance, resulting in excessive production of reactive oxygen species. Oxidative stress is viewed as a critical pathogenic factor implicated in the initiation, development, and progression of most renal diseases. This Forum discusses the redox-dependent factors and mechanisms accounting for the perturbation of renal function and circulation in the context of the major kidney pathologies linked to hypertension, diabetes, and cancer. Antioxid. Redox Signal. 25, 639-641.

Greater Wound and Renal Complications in Gout Patients Undergoing Total Joint Arthroplasty

BACKGROUND

Little is known about total joint arthroplasty (TJA) outcomes in gout patients. The purpose of this study was to compare adverse events between gout and nongout patients who underwent primary TJA.

METHODS

Using our institutional database and medical records review, a retrospective case-control study was conducted. From 2000 to 2012, a total of 482 gout TJA patients were matched with nongout TJA patients in a 1:1 ratio. Length of stay, complications, 90-day emergency room visits, and 90-day readmissions in these patients were compared.

RESULTS

Gout patients had greater wound healing problems (12.2% vs 5.0%, P = .001) and renal complications (8.9% vs 3.1%, P = .0003) compared with nongout patients. There were no significant differences between gout and nongout patients in terms of mean length of hospital stay (3.82 vs 3.17 days, P = .11) and 90-day emergency room visits (5.6% vs 3.5%, P = 1.00). Subgroup analysis showed that 90-day readmission rates were higher in gout patients who underwent total hip arthroplasty compared with those in nongout THA patients (6.8% vs 2.1%, P = .02).

CONCLUSION

Gout patients undergoing TJA have greater wound healing problems and renal complications. Surgeons should be cognizant of fluid management, renal monitoring and wound issues and should be cautious when treating TJA gout patients.

Frailty as a Predictor of Acute Kidney Injury in Hospitalized Elderly Patients: A Single Center, Retrospective Cohort Study

BACKGROUND

Elderly patients have an increased risk for acute kidney injury (AKI). However, few studies have reported on predictors for AKI in geriatric patients. Therefore, we aimed at determining the effect of frailty as a predictor of AKI.

METHODS

We retrospectively enrolled 533 hospitalized elderly patients (aged ≥ 65 years) who had their creatinine levels measured (≥ 1 measurement) during admission for a period of 1 year (2013) and conducted a comprehensive geriatric assessment (CGA) within 1 year before the index hospitalization. We examined five variables (activity of daily living [ADL] and instrumental ADL dependence, dementia, nutrition, and polypharmacy) from CGA. We categorized the patients into 3 groups according to the tertile of aggregate frailty scores: Group 1, score 1-2; Group 2, score 3-4; Group 3, score 5-8).

RESULTS

Fifty-four patients (10.1%) developed AKI (median duration, 4 days). The frailest group (Group 3) showed an increased risk of AKI as compared to Group 1, (hazard ratio [HR] = 3.536, P = 0.002). We found that discriminatory accuracy for AKI improved with the addition of the tertile of aggregate frailty score to covariates (area under the receiver operator characteristics curves [AUROC] 0.641, AUROC 0.739, P = 0.004). Forty-six patients (8.6%) were transferred to nursing facilities and 477 patients (89.5%) were discharged home. The overall 90-day and 1-year mortality for elderly inpatients were 7.9% and 26.3%. The frailest group also demonstrated an increased risk of discharge to nursing facilities, and 90-day and 1-year mortality as compared to Group 1, independent of AKI severity (nursing facilities: odd ratio = 4.843, P = 0.002; 90-day mortality: HR = 6.555, P = 0.002; 1-year mortality: HR = 3.249, P = 0.001).

CONCLUSIONS

We found that frailty may independently predict the development of AKI and adverse outcomes in geriatric inpatients.

Risk Stratification for Acute Kidney Injury: Are Biomarkers Enough?

Acute kidney injury (AKI) is a common and serious complication that is associated with several adverse outcomes in hospitalized patients. AKI significantly increases the risk of mortality, need for renal replacement therapy, and intensive care admission, and it also has serious economic ramifications. Effective risk stratification to identify patients at risk for severe AKI is essential for targeting our health care and research resources to tackle this important public health issue. The overwhelming majority of research in earlier diagnosis and risk stratification of AKI over the past 10 years has focused on novel biomarker development. The purpose of this review is to provide an update on other novel risk stratification tools than can be used in the prognostication of AKI. We discuss the utility of the furosemide stress test in predicting the severity of AKI and the renal angina index in predicting the occurrence of AKI. We also discuss NephroCheck, a prognostic test that measures tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 for the early detection of severe AKI.

Renocardiac syndromes: physiopathology and treatment stratagems

Purpose of review

Bidirectional inter-organ interactions are essential for normal functioning of the human body; however, they may also promote adverse conditions in remote organs. This review provides a narrative summary of the epidemiology, physiopathological mechanisms and clinical management of patients with combined renal and cardiac disease (recently classified as type 3 and 4 cardiorenal syndrome). Findings are also discussed within the context of basic research in animal models with similar comorbidities.

Sources of information

Pertinent published articles were identified by literature search of PubMed, MEDLINE and Google Scholar. Additional data from studies in the author’s laboratory were also consulted.

Findings

The prevalence of renocardiac syndrome throughout the world is increasing in part due to an aging population and to other risk factors including hypertension, diabetes and dyslipidemia. Pathogenesis of this disorder involves multiple bidirectional interactions between the kidneys and heart; however, participation of other organs cannot be excluded. Our own work supports the hypothesis that the uremic milieu, caused by kidney dysfunction, produces major alterations in vasoregulatory control particularly at the level of the microvasculature that results in impaired oxygen delivery and blood perfusion.

Limitations

Recent clinical literature is replete with articles discussing the necessity to clearly define or characterize what constitutes cardiorenal syndrome in order to improve clinical management of affected patients. Patients are treated after onset of symptoms with limited available information regarding etiology. While understanding of mechanisms involved in pathogenesis of inter-organ crosstalk remains a challenging objective, basic research data remains limited partly because of the lack of animal models.

Implications

Preservation of microvascular integrity may be the most critical factor to limit progression of multi-organ disorders including renocardiac syndrome. More fundamental studies are needed to help elucidate physiopathological mechanisms and for development of treatments to improve clinical outcomes.

Clinical Risk Scoring Models for Prediction of Acute Kidney Injury after Living Donor Liver Transplantation: A Retrospective Observational Study

Acute kidney injury (AKI) is a frequent complication of liver transplantation and is associated with increased mortality. We identified the incidence and modifiable risk factors for AKI after living-donor liver transplantation (LDLT) and constructed risk scoring models for AKI prediction. We retrospectively reviewed 538 cases of LDLT. Multivariate logistic regression analysis was used to evaluate risk factors for the prediction of AKI as defined by the RIFLE criteria (RIFLE = risk, injury, failure, loss, end stage). Three risk scoring models were developed in the retrospective cohort by including all variables that were significant in univariate analysis, or variables that were significant in multivariate analysis by backward or forward stepwise variable selection. The risk models were validated by way of cross-validation. The incidence of AKI was 27.3% (147/538) and 6.3% (34/538) required postoperative renal replacement therapy. Independent risk factors for AKI by multivariate analysis of forward stepwise variable selection included: body-mass index >27.5 kg/m² [odds ratio (OR) 2.46, 95% confidence interval (CI) 1.32–4.55], serum albumin <3.5 mg/dl (OR 1.76, 95%CI 1.05–2.94), MELD (model for end-stage liver disease) score >20 (OR 2.01, 95%CI 1.17–3.44), operation time >600 min (OR 1.81, 95%CI 1.07–3.06), warm ischemic time >40 min (OR 2.61, 95%CI 1.55–4.38), postreperfusion syndrome (OR 2.96, 95%CI 1.55–4.38), mean blood glucose during the day of surgery >150 mg/dl (OR 1.66, 95%CI 1.01–2.70), cryoprecipitate > 6 units (OR 4.96, 95%CI 2.84–8.64), blood loss/body weight >60 ml/kg (OR 4.05, 95%CI 2.28–7.21), and calcineurin inhibitor use without combined mycophenolate mofetil (OR 1.87, 95%CI 1.14–3.06). Our risk models performed better than did a previously reported score by Utsumi et al. in our study cohort. Doses of calcineurin inhibitor should be reduced by combined use of mycophenolate mofetil to decrease postoperative AKI. Prospective randomized trials are required to address whether artificial modification of hypoalbuminemia, hyperglycemia and postreperfusion syndrome would decrease postoperative AKI in LDLT.