Chronic Kidney Disease, Heart Failure, and Adverse Cardiac Remodeling in Older Adults: The ARIC Study.

BACKGROUND: The associations of kidney dysfunction and damage with heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF), as well as adverse cardiac remodeling, in late-life remain incompletely understood. OBJECTIVES: The authors sought to define the associations between kidney dysfunction and damage and incident HFrEF and HFpEF and cardiac structure and function in late-life. METHODS: This study included 5,170 adults initially free of a heart failure (HF) diagnosis who had estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR) measured at visit 5 (2011-2013) of the ARIC (Atherosclerosis Risk In Communities) study. Multivariable Cox proportional hazards models were used to estimate the associations of eGFR and UACR with incident HF, HFrEF, and HFpEF through 2019. Multivariable linear regression models were used to investigate the associations of eGFR and UACR at visit 5 with changes in cardiac structure and function between visits 5 and 7 in 2,313 participants with available echocardiograms. RESULTS: The mean age of participants was 76 ± 5 years, and 2,225 (43%) were men. The mean eGFR and median UACR were 66 ± 18 mL/min/1.73 m2 and 11 mg/g (25th, 75th percentile: 6, 22 mg/g), respectively. In fully adjusted models, both lower eGFR and higher UACR were associated with greater risk of any HF, HFrEF, and HFpEF. Lower eGFR was associated with larger increases in left ventricular end-diastolic volume index and worsening of diastolic measures. UACR did not associate with changes in cardiac structure or function. CONCLUSIONS: Mild to moderate kidney dysfunction and damage associate with incident HF and adverse cardiac remodeling in late-life.

The fetal origins of disease: a prospective cohort study on the association of preeclampsia and childhood obesity.

Cardiovascular diseases are the main cause of mortality worldwide, and childhood excess weight/obesity are strong correlators of accumulated risk in later life. A relationship between maternal preeclampsia and offspring's childhood obesity is recognized, but most studies fail to control for strong confounders. Our goal is to analyze the association between preeclampsia and childhood excess weight/obesity, after accounting for important confounders. We recruited 5133 women with singleton pregnancies during admission for delivery. Sixty-seven pregnancies were complicated by preeclampsia. Maternal and children outcomes were assessed at 10 years of age. We analyzed the association between preeclampsia and childhood excess weight/obesity by fitting a linear regression model (using offspring body mass index (BMI) z-score at 10 years of age) and a logistic regression model (using excess weight/obesity status). We then controlled both models for known confounders, namely maternal prepregnancy BMI, parity, and smoking during pregnancy. At 10 years of age, offspring of preeclamptic mothers had a higher BMI z-score and were more likely classified as overweight/obese, but these differences were not statistically significant. After controlling for maternal prepregnancy BMI, parity, and smoking during pregnancy, there was a high magnitude change in the beta coefficient of preeclampsia in the linear (0.175; -0.014) and the logistic regression models (1.48; 1.23) suggesting that the association between preeclampsia and childhood excess weigh/obesity is significantly confounded by these variables. These confounders also showed a significant association with childhood obesity. This finding suggests that in utero exposure to preeclampsia seems to have less impact in childhood obesity than the previously described confounders.

Plasma Kidney Injury Molecule 1 in CKD: Findings From the Boston Kidney Biopsy Cohort and CRIC Studies.

RATIONALE & OBJECTIVE: Plasma kidney injury molecule 1 (KIM-1) is a sensitive marker of proximal tubule injury, but its association with risks of adverse clinical outcomes across a spectrum of kidney diseases is unknown. STUDY DESIGN: Prospective, observational cohort study. SETTING & PARTICIPANTS: 524 individuals enrolled into the Boston Kidney Biopsy Cohort (BKBC) Study undergoing clinically indicated native kidney biopsy with biopsy specimens adjudicated for semiquantitative scores of histopathology by 2 kidney pathologists and 3,800 individuals with common forms of chronic kidney disease (CKD) enrolled into the Chronic Renal Insufficiency Cohort (CRIC) Study. EXPOSURE: Histopathologic lesions and clinicopathologic diagnosis in cross-sectional analyses, baseline plasma KIM-1 levels in prospective analyses. OUTCOMES: Baseline plasma KIM-1 levels in cross-sectional analyses, kidney failure (defined as initiation of kidney replacement therapy) and death in prospective analyses. ANALYTICAL APPROACH: Multivariable-adjusted linear regression models tested associations of plasma KIM-1 levels with histopathologic lesions and clinicopathologic diagnoses. Cox proportional hazards models tested associations of plasma KIM-1 levels with future kidney failure and death. RESULTS: In the BKBC Study, higher plasma KIM-1 levels were associated with more severe acute tubular injury, tubulointerstitial inflammation, and more severe mesangial expansion after multivariable adjustment. Participants with diabetic nephropathy, glomerulopathies, and tubulointerstitial disease had significantly higher plasma KIM-1 levels after multivariable adjustment. In the BKBC Study, CKD in 124 participants progressed to kidney failure and 85 participants died during a median follow-up time of 5 years. In the CRIC Study, CKD in 1,153 participants progressed to kidney failure and 1,356 participants died during a median follow-up time of 11.5 years. In both cohorts, each doubling of plasma KIM-1 level was associated with an increased risk of kidney failure after multivariable adjustment (hazard ratios of 1.19 [95% CI, 1.03-1.38] and 1.10 [95% CI, 1.06-1.15] for BKBC and CRIC, respectively). There was no statistically significant association of plasma KIM-1 levels with death in either cohort. LIMITATIONS: Generalizability and unmeasured confounding. CONCLUSIONS: Plasma KIM-1 is associated with underlying tubulointerstitial and mesangial lesions and progression to kidney failure in 2 cohort studies of individuals with kidney diseases.

Corrigendum to "Transjugular Kidney Biopsy as a Safe Method to Increase the Etiological Diagnosis in Kidney Disease" Kidney Int. Rep. 2021;6:2535-2536.

[This corrects the article DOI: 10.1016/j.ekir.2021.08.007.].

Histopathologic Correlates of Kidney Function: Insights From Nephrectomy Specimens.

RATIONALE & OBJECTIVE: Existing data sets correlating kidney histopathologic findings with kidney function have low proportions of elderly patients (and those with a family history of kidney failure are over-represented), which limits their generalizability. Our objective was to use non-neoplastic tissue from nephrectomy specimens to examine the association between degree of histopathologic changes and estimated glomerular filtration rate (eGFR) and determine whether the association differed by age. STUDY DESIGN: Cross-sectional study. EXPOSURES: Glomerulosclerosis (GS), interstitial fibrosis/tubular atrophy (IFTA), and arterial sclerosis/arteriosclerosis (AS). OUTCOME: eGFR. ANALYTICAL APPROACH: We retrospectively reviewed kidney pathology reports (of non-neoplastic tissue) from 1,347 patients who underwent nephrectomy (1999-2018) for any indication but most commonly due to kidney cancer. We evaluated the association between degree of GS, IFTA, and AS with eGFR at the time of nephrectomy and whether this was modified by age. RESULTS: Among the participants (aged 17-91 years), 42% and 57.8% had>10% GS and IFTA, respectively, and 81.8% had moderate or severe AS. We found that greater degrees of GS, IFTA, and AS were associated with lower eGFR after multivariable adjustment. Although there was a greater prevalence of more severe degrees of GS and IFTA in older individuals, the association between various histopathologic features and eGFR was not modified by age. LIMITATIONS: Retrospective cross-sectional study. CONCLUSIONS: Our study demonstrates differences in the histologic appearance of the kidneys across levels of eGFR. Although the prevalence of advanced changes was higher in the oldest group of patients, a subset had excellent kidney function and limited histologic changes.

Incidence of Hyponatremia in Patients With Indwelling Peritoneal Catheters for Drainage of Malignant Ascites.

Importance: Indwelling peritoneal catheters (IPCs) are frequently used to drain tense, symptomatic, malignant ascites. Large-volume drainage may lead to hyponatremia owing to massive salt depletion. To date, no studies have examined the epidemiology of hyponatremia after placement of an IPC. Objective: To evaluate the incidence of hyponatremia after IPC placement, the risk factors associated with its development, and how it is managed. Design, Setting, and Participants: This cohort study retrospectively reviewed the medical records of 461 patients who had IPCs placed during the period between 2006 and 2016 at a tertiary care hospital in Boston, Massachusetts, of whom 309 patients met the inclusion criteria. Data analysis was performed from June to November 2019. Main Outcomes and Measures: Main outcomes were the incidence of hyponatremia (with a serum sodium level <135 mEq/L) after IPC placement, the risk factors for its development, and how it was managed. We also examined the clinical course of a subset of 21 patients with hypovolemic hyponatremia. Results: Of the 309 eligible patients with laboratory results both before IPC placement and 2 days or more after IPC placement, 189 (72.1%) were female, and the mean (SD) age was 59 (12) years. The overall incidence of hyponatremia after IPC placement was 84.8% (n = 262), of whom 21 patients (8.0%) had severe hyponatremia. The mean (SD) decrease in serum sodium level before vs after IPC placement was 5 (5.1) mEq/L and decreased by 10 mEq/L or more among 52 patients (16.8%). Patients with hyponatremia prior to IPC placement had an 8-fold higher adjusted odds of having persistent hyponatremia after IPC placement (odds ratio, 7.9; 95% CI, 2.9-21.7). Patients with hepatopancreatobiliary malignant neoplasms were more likely to develop hyponatremia (78 of 262 patients with hyponatremia [29.8%] vs 7 of 47 patients without hyponatremia [14.9%]). Hyponatremia was either unrecognized or untreated in 189 patients (72.1%). Conclusions and Relevance: Although the placement of an IPC is often a palliative measure, hyponatremia is common and is often untreated or unrecognized. Patients at highest risk, such as those with hyponatremia at baseline and those with hepatopancreatobiliary malignant neoplams, should be evaluated carefully prior to IPC placement and may warrant closer monitoring after placement. In all cases, hyponatremia should be evaluated and managed within the context of a patient's overall goals of care.

Systematic Review and Meta-Analysis of Native Kidney Biopsy Complications.

BACKGROUND AND OBJECTIVES: Native kidney biopsies are commonly performed in the diagnosis of acute kidney diseases and CKD. Because of the invasive nature of the procedure, bleeding-related complications are not uncommon. The National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases-sponsored Kidney Precision Medicine Project requires that all participants undergo a kidney biopsy; therefore, the objective of this analysis was to study complication rates of native kidney biopsies performed using automated devices under kidney imaging. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This is a systematic review and meta-analysis of the literature published from January 1983 to March 2018. The initial PubMed search yielded 1139 manuscripts. Using predetermined selection criteria, 87 manuscripts were included in the final analysis. A random effects meta-analysis for proportions was used to obtain combined estimates of complication rates. Freeman-Tukey double-arcsine transformations were used to stabilize variance as complications were rare. RESULTS: A total of 118,064 biopsies were included in this study. Patient age ranged from 30 to 79 years, and 45% of patients were women. On the basis of our meta-analysis, pain at the site of biopsy is estimated to occur in 4.3% of biopsied patients, hematomas are estimated to occur in 11%, macroscopic hematuria is estimated to occur in 3.5%, bleeding requiring blood transfusions is estimated to occur in 1.6%, and interventions to stop bleeding are estimated to occur in only 0.3%. Death attributed to native kidney biopsy was a rare event, occurring only in an estimated 0.06% of all biopsies but only 0.03% of outpatient biopsies. Complication rates were higher in hospitalized patients and in those with acute kidney disease. The reported complications varied on the basis of study type and geographic location. CONCLUSIONS: Although the native kidney biopsy is an invasive diagnostic procedure, the rates of bleeding complications are low. Albeit rare, death can occur postbiopsy. Complications are more frequently seen after kidney biopsies of hospitalized patients with AKI.

Renal deposits of complement factors as predictors of end-stage renal disease and death in patients with lupus nephritis.

OBJECTIVE: Lupus nephritis (LN) increases the risks of end-stage renal disease (ESRD) and death, but these risks are difficult to estimate. Since complement factors play an essential role in the pathogenesis and are deposited in the kidneys as C1q and C3, we studied whether these deposits predict ESRD and death in patients with LN. METHODS: We collected demographic, clinical and pathological data from 183 adult patients with LN classes II-V diagnosed with a first native kidney biopsy. Pathological data included the localization and intensity of immunofluorescence staining of C1q and C3. We obtained dates of incident ESRD and death from the United States Renal Data System and National Death Index, respectively, and evaluated survival curves and hazard ratios for ESRD and death as a composite outcome and as separate outcomes. RESULTS: The presence and intensity of deposits of C1q and C3 in glomeruli, tubular walls and vascular walls differed between classes and were associated with known unfavourable prognostic factors, such as hypertension, hypoalbuminemia and hypocomplementemia. However, over a median follow-up of 7.5 years, their presence and intensity were associated with neither survival free of ESRD and death nor hazard ratios for ESRD and death. CONCLUSION: Renal deposits of complement factors did not predict ESRD and death in patients with LN.

Bleeding Complications After Percutaneous Native Kidney Biopsy: Results From the Boston Kidney Biopsy Cohort.

BACKGROUND: The major risk of kidney biopsy is severe bleeding. Numerous risk factors for bleeding after biopsy have been reported, but findings have been inconsistent. METHODS: We retrospectively reviewed medical records of adult patients enrolled in a native kidney biopsy cohort study to identify major bleeding events (red blood cell [RBC] transfusions, invasive procedures, kidney loss, or death). We used logistic and linear regression models to identify characteristics associated with postbiopsy RBC transfusions and decline in hemoglobin within a week after the procedure. RESULTS: Major bleeding events occurred in 28 of 644 (4.3%) patients (28 required an RBC transfusion, 4 underwent angiographic intervention, and 1 had open surgery to control bleeding). No patient lost a kidney or died because of the biopsy. Postbiopsy RBC transfusion risk was driven by the baseline hemoglobin level (odds ratio [OR] 13.6; 95% confidence interval [CI] 5.4-34.1 for hemoglobin <10 vs. ≥10 g/dl). After adjusting for hemoglobin, no other patient characteristics were independently associated with RBC transfusions. Female sex (ß = 0.18; 95% CI: 0.04-0.32), estimated glomerular filtration rate (eGFR) <30 ml/min per 1.73 m2 (ß = 0.32; 95% CI: 0.14-0.49), and baseline hemoglobin (ß = 0.09; 95% CI: 0.05-0.13, per g/dl increase) were independently associated with a larger drop in hemoglobin. Histopathologic lesions were not independently associated with major bleeding after biopsy. CONCLUSION: Biopsies were generally well tolerated. Baseline hemoglobin was the dominant risk factor for RBC transfusions, but female sex and eGFR <30 ml/min per 1.73 m2 were also associated with a larger decline in hemoglobin after the procedure.

The association of calcium oxalate deposition in kidney allografts with graft and patient survival.

BACKGROUND: Whether calcium oxalate (CaOx) deposition in kidney allografts following transplantation (Tx) adversely affects patient outcomes is uncertain, as are its associated risk factors. METHODS: We performed a retrospective cohort study of patients who had kidney allograft biopsies performed within 3 months of Tx at Brigham and Women's Hospital and examined the association of CaOx deposition with the composite outcome of death or graft failure within 5 years. RESULTS: Biopsies from 67 of 346 patients (19.4%) had CaOx deposition. In a multivariable logistic regression model, higher serum creatinine [odds ratio (OR) = 1.28 per mg/dL, 95% confidence interval (CI) 1.15-1.43], longer time on dialysis (OR = 1.11 per additional year, 95% CI 1.01-1.23) and diabetes (OR = 2.26, 95% CI 1.09-4.66) were found to be independently associated with CaOx deposition. CaOx deposition was strongly associated with delayed graft function (DGF; OR = 11.31, 95% CI 5.97-21.40), and with increased hazard of the composite outcome after adjusting for black recipient race, donor type, time on dialysis before Tx, diabetes and borderline or acute rejection (hazard ratio 1.90, 95% CI 1.13-3.20). CONCLUSIONS: CaOx deposition is common in allografts with poor function and portends worse outcomes up to 5 years after Tx. The extent to which CaOx deposition may contribute to versus result from DGF, however, cannot be determined based on our retrospective and observational data. Future studies should examine whether reducing plasma and urine oxalate prevents CaOx deposition in the newly transplanted kidney and whether this has an effect on clinical outcomes.

"Pleurex Desalination" in Malignancy-related Ascites: A Novel Mechanism of Hyponatremia.

OBJECTIVE: Pleurex catheters are a form of palliative therapy for patients, offering relief from symptomatic ascites while also affording greater independence and flexibility; however, aggressive drainage can lead to significant total body sodium losses. We describe the course of patients with "Pleurex desalination," an under-appreciated cause of hypovolemic hyponatremia, highlighting its unique pathophysiology and providing recommendations on how to manage these complex patients. PATIENTS AND METHODS: We included representative patients with "Pleurex desalination" who were evaluated and treated by the renal consult service at Brigham and Women's between 2017 and 2019. RESULTS: We identified 3 patients who were hospitalized with "Pleurex desalination" and had complete data on serum and urine studies, as well as treatment course. We demonstrate that patients with "Pleurex desalination" were removing up to 1 to 2 L of ascitic fluid a day and were admitted with signs and symptoms of profound hypovolemia and hyponatremia. Patients worsened with administration of diuretics and salt restriction and improved with aggressive fluid resuscitation in the form of hypertonic saline, normal saline, and/or intravenous albumin. CONCLUSION: "Pleurex desalination" is an under-recognized cause of hyponatremia; at-risk patients require close observation and periodic resuscitation with intravenous, volume-expanding fluids.

Prolyl-hydroxylase inhibitors for the treatment of anemia in chronic kidney disease.

PURPOSE OF REVIEW: Prolyl-hydroxylase inhibitors are a novel class of orally administered drugs that are under development for the treatment of anemia in patients with chronic kidney disease. This review discusses the biology of these drugs and their target - hypoxia-inducible factor and potential advantages and disadvantages of these therapies. Finally, we will discuss current trials in patients with both chronic kidney disease and end-stage renal disease. RECENT FINDINGS: Recent smaller studies have found that prolyl-hydroxylase are as effective as erythropoietin in treating anemia of chronic kidney disease. We do not yet know if they have the same cardiovascular and cancer-related risk profile and these questions will be answered by large phase III trials that are ongoing. SUMMARY: Although prolyl hydroxylase inhibitors have much potential, questions remain regarding their efficacy and safety. Should these concerns prove to be unfounded, the treatment of anemia in chronic kidney disease will likely be transformed over the next decade.

Clinical characteristics and renal prognosis associated with interstitial fibrosis and tubular atrophy (IFTA) and vascular injury in lupus nephritis biopsies.

BACKGROUND: Interstitial fibrosis and tubular atrophy (IFTA) and vascular injury are frequent histologic features of lupus nephritis renal biopsies, but their clinical correlates and prognostic value are not well understood. This cohort study investigated demographic, clinical and laboratory characteristics, and outcomes, associated with IFTA and vascular injury in lupus nephritis. METHODS: Reports of all renal biopsies performed at an academic medical center (1990-2017) with WHO/ISN/RPS Class II-V lupus nephritis were reviewed. Demographics, clinical variables and labs at biopsy, treatment, and date of death were collected. Additional data from the U.S. Renal Data System (USRDS) provided dates of ESRD and death after ESRD. Multivariable regression analyses identified demographic and clinical factors associated with each histologic finding. Cumulative incidence functions and multivariable Cox proportional hazard models estimated the risk of progression to ESRD and death. RESULTS: Within 202 initial biopsies, IFTA was associated with the patient's SLICC/ACR damage index (without renal domain) and serum creatinine, and vascular injury was associated with serum creatinine in multivariable models. In Cox regression models adjusting for age, sex, race, serum creatinine, calendar year, and biopsy class, moderate/severe IFTA was associated with elevated ESRD (HRSD 5.18, 95% CI 2.53, 10.59) and death (HR 4.19, 95%CI 1.27, 13.81). After adjustment for age, sex and race, moderate/severe vascular injury was associated with ESRD (HRSD 2.13, 95% CI 1.21, 3.75) and but this relationship was not significant after adjustment for serum creatinine and calendar year. CONCLUSIONS: IFTA is a strong predictor of ESRD and death, even in proliferative nephritis, and a risk factor for poor outcomes independent of class. Vascular injury is a strong predictor of prognosis, but not independent of serum creatinine and class. The prognostic value of these lesions calls for consideration when determining treatment for lupus nephritis.

The Prognostic Value of Histopathologic Lesions in Native Kidney Biopsy Specimens: Results from the Boston Kidney Biopsy Cohort Study.

Background Few studies have evaluated whether histopathologic lesions on kidney biopsy provide prognostic information beyond clinical and laboratory data.Methods We enrolled 676 individuals undergoing native kidney biopsy at three tertiary care hospitals into a prospective, observational cohort study. Biopsy specimens were adjudicated for semiquantitative scores in 13 categories of histopathology by two experienced renal pathologists. Proportional hazards models tested the association between histopathologic lesions and risk of kidney disease progression (≥40% eGFR decline or RRT).Results Mean baseline eGFR was 57.5±36.0 ml/min per 1.73 m2 During follow-up (median, 34.3 months), 199 individuals suffered kidney disease progression. After adjustment for demographics, clinicopathologic diagnosis, and laboratory values, the following lesions (hazard ratio; 95% confidence interval) were independently associated with progression: inflammation in nonfibrosed interstitium (0.52; 0.32 to 0.83), moderate and severe versus minimal interstitial fibrosis/tubular atrophy (2.14; 1.24 to 3.69 and 3.42; 1.99 to 5.87, respectively), moderate and severe versus minimal global glomerulosclerosis (2.17; 1.36 to 3.45 and 3.31; 2.04 to 5.38, respectively), moderate and severe versus minimal arterial sclerosis (1.78; 1.15 to 2.74 and 1.64; 1.04 to 2.60, respectively), and moderate and severe versus minimal arteriolar sclerosis (1.63; 1.08 to 2.46 and 2.33; 1.42 to 3.83, respectively). An 11-point chronicity score derived from semiquantitative assessments of chronic lesions independently associated with higher risk of kidney disease progression (hazard ratio per one-point increase, 1.19; 95% confidence interval, 1.12 to 1.27).Conclusions Across a diverse group of kidney diseases, histopathologic lesions on kidney biopsy provide prognostic information, even after adjustment for proteinuria and eGFR.

Development and Validation of a Risk Prediction Model for Acute Kidney Injury After the First Course of Cisplatin.

Purpose Cisplatin-associated acute kidney injury (C-AKI) is common. We sought to develop and validate a predictive model for C-AKI after the first course of cisplatin. Methods Clinical and demographic data were collected on patients who received cisplatin between 2000 and 2016 at two cancer centers. C-AKI was defined as a 0.3 mg/dL rise in serum creatinine within 14 days of receiving cisplatin. Using multivariable logistic regression models with C-AKI as the primary outcome, we created a scoring model from the development cohort (DC) and tested it in the validation cohort (VC). Results C-AKI occurred in 13.6% of 2,118 patients in the DC and in 11.6% of 2,363 patients in the VC. Factors significantly associated with C-AKI included age 61 to 70 years (odds ratio [OR], 1.64 [95% CI, 1.21 to 2.23]; P = .001) and 71 to 90 years (OR, 2.97 [95% CI, 2.06 to 4.28]; P < .001) compared with ≤ 60 years; cisplatin dose 101 to 150 mg (OR, 1.58 [95% CI, 1.14 to 2.19]; P = .007) and > 150 mg (OR, 3.73 [95% CI, 2.68 to 5.20]; P < .001) compared with ≤ 100 mg; a history of hypertension (OR, 2.10 [95% CI, 1.54 to 2.72]; P < .001) compared with no hypertension; and serum albumin 2.0 to 3.5 g/dL (OR, 2.21 [95% CI, 1.62 to 3.03]; P < .001) compared with > 3.5 g/dL. The baseline estimated glomerular filtration rate was not significantly associated with the risk of C-AKI. The c-statistics of the score-based model in the DC and the VC were 0.72 (95% CI, 0.69 to 0.75) and 0.70 (95% CI, 0.67 to 0.73), respectively. Scores of 0, 3.5, and 8.5 were associated with a probability of C-AKI of 0.03 (95% CI, 0.03 to 0.05), 0.12 (95% CI, 0.11 to 0.14), and 0.51 (95% CI, 0.43 to 0.60), respectively. Conclusion A score-based model created by using the patient's age, cisplatin dose, hypertension, and serum albumin is predictive of C-AKI.

Expanding the Role for Kidney Biopsies in Acute Kidney Injury.

Acute kidney injury (AKI) is a highly heterogeneous, common, and potentially devastating condition associated with markedly increased hospital length of stay, cost, mortality, and morbidity. Expanding the role for kidney biopsies in AKI may offer fresh insights into disease heterogeneity, molecular mechanisms, and therapeutic targets. A number of challenges face investigators and clinicians considering research biopsies in AKI: ensuring patient safety, ensuring the ethical conduct of research studies, and maximizing the scientific yield of the kidney tissue obtained. The societal benefits of research that lead to novel strategies for preventing and treating AKI would be enormous. Rethinking our current approach to the role of kidney biopsy for AKI diagnosis and research may be a major step toward the promise of personalized medicine in nephrology.

Length Polymorphisms in Heme Oxygenase-1 and AKI after Cardiac Surgery.

Heme oxygenase-1 (HO-1) catalyzes the degradation of heme, which may be involved in the pathogenesis of AKI. Length polymorphisms in the number of GT dinucleotide repeats in the HO-1 gene (HMOX1) promoter inversely associate with HMOX1 mRNA expression. We analyzed the association between allelic frequencies of GT repeats in the HMOX1 gene promoter and postoperative AKI in 2377 white patients who underwent cardiac surgery with cardiopulmonary bypass. We categorized patients as having the short allele (S; <27 GT repeats) or long allele (L; ≥27 GT repeats), and defined AKI as an increase in serum creatinine ≥0.3 mg/dl within 48 hours or ≥50% within 5 days, or the need for RRT. Compared with patients with the SS genotype, patients with the LL genotype had 1.58-fold (95% confidence interval, 1.06 to 2.34; P=0.02) higher odds of AKI. After adjusting for baseline and operative characteristics, the odds ratio for AKI per L allele was 1.26 (95% confidence interval, 1.05 to 1.50; P=0.01). In conclusion, longer GT repeats in the HMOX1 gene promoter associate with increased risk of AKI after cardiac surgery, consistent with heme toxicity as a pathogenic feature of cardiac surgery-associated AKI, and with HO-1 as a potential therapeutic target.

Excessive diagnostic testing in acute kidney injury.

BACKGROUND: The patterns, performance characteristics, and yield of diagnostic tests ordered for the evaluation of acute kidney injury (AKI) have not been rigorously evaluated. METHODS: We characterized the frequency of AKI diagnostic testing for urine, blood, radiology, and pathology tests in all adult inpatients who were admitted with or developed AKI (N = 4903 patients with 5731 AKI episodes) during a single calendar year. We assessed the frequency of abnormal test results overall and by AKI stage. We manually reviewed electronic medical records to evaluate the diagnostic yield of selected urine, blood, and radiology tests. Diagnostic yield of urine and blood tests was determined based on whether an abnormal test affected AKI diagnosis or management, whereas diagnostic yield of radiology tests was based on whether an abnormal test resulted in a procedural intervention. In sensitivity analyses we also evaluated appropriateness of testing using prespecified criteria. RESULTS: Frequency of testing increased with higher AKI stage for nearly all diagnostic tests, whereas frequency of detecting an abnormal result increased for some, but not all, tests. Frequency of detecting an abnormal result was highly variable across tests, ranging from 0 % for anti-glomerular basement membrane testing to 71 % for urine protein testing. Many of the tests evaluated had low diagnostic yield. In particular, selected urine and blood tests were unlikely to impact AKI diagnosis or management, whereas radiology tests had greater clinical utility. CONCLUSIONS: In patients with AKI, many of the diagnostic tests performed, even when positive or abnormal, may have limited clinical utility.