Incidence and Consequences of Acute Kidney Injury in Kidney Transplant Recipients

Epithelial CEBPD activates fibronectin and enhances macrophage adhesion in renal ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is a cause of acute kidney injury in patients after renal transplantation and leads to high morbidity and mortality. Damaged kidney resident cells release cytokines and chemokines, which rapidly recruit leukocytes. Fibronectin (FN-1) contributes to immune cell migration, adhesion and growth in inflamed tissues. CCAAT/enhancer-binding protein delta is responsive to inflammatory cytokines and stresses and plays functional roles in cell motility, extracellular matrix production and immune responses. We found that the expression of CCAAT/enhancer-binding protein delta was increased in renal epithelial cells in IRI mice compared with sham mice. Following IRI, the colocalization of FN-1 with the macrophage marker F4/80 was increased in renal injury model wild-type mice but was significantly attenuated in Cebpd-deficient mice. Inactivation of CEBPD can repress hypoxia-induced FN-1 expression in HK-2 cells. Moreover, the inactivation of CEBPD and FN-1 also reduces macrophage accumulation in HK-2 cells. These findings suggest that the involvement of CEBPD in macrophage accumulation through the activation of FN-1 expression and the inhibition of CEBPD can protect against renal IRI.

Acute post-renal kidney graft dysfunction due to cytomegalovirus-positive nephrogenic adenoma-case report and review of the literature

Tissue-invasive cytomegalovirus (CMV) disease represents a well-recognized complication after kidney transplantation. However, direct involvement of the urogenital tract and CMV-ureteritis occur less frequently. Nephrogenic adenomas are benign lesions of the urinary tract preferentially reported in kidney transplant recipients. We herein report a second case of a 33-year-old male kidney transplant recipient with acute post-renal allograft dysfunction due to CMV-positive ureteral nephrogenic adenoma. A causal connection might be suspected but remains to be proven.

Management of kidney transplant recipients for primary care practitioners

Patients with kidney transplants have a significant co-morbidity index, due to a high number of pre-existing conditions and use of immunosuppression medications. These patients are at higher risk of developing conditions such as hypertension, dyslipidemia, post-transplant diabetes, cardiovascular events, and anemia. Moreover, they are particularly susceptible to infections such as urinary tract infections or pyelonephritis, cancers, and gastrointestinal complications such as diarrhea, which in turn may be attributed to medication adverse effects or infectious causes. Along with these concerns, meticulous management of electrolytes and allograft function is essential. Prior to prescribing any new medications, it is imperative to exercise caution in identifying potential interactions with immunosuppression drugs. This review aims to equip primary care practitioners to address these complex issues and appropriate methods of delivering care to this rapidly growing highly susceptible group.

Management of the kidney transplant recipient in the intensive care unit

PURPOSE OF REVIEW

Kidney transplantation is the ideal treatment for patients with chronic kidney disease and end stage renal disease. While centers are performing more transplants every year, the need for organ transplantation outpaces the supply of organ donors. Due to a growing population of patients with advanced kidney disease and a scarcity of kidneys from deceased donors, patients face extended wait times. By the time patients approach transplantation they have multiple comorbidities, in particular cardiovascular complications. Their risk of complications is further compounded by exposure to immunosuppression post kidney transplantation. Kidney transplant recipients (KTRs) are medically complex and may require acute management in the intensive care unit (ICU), as a result of cardiovascular complications, infections, and/or respiratory compromise from lung infections and/or acute pulmonary edema. Acute complication of immunosuppression, such as thrombotic microangiopathy and posterior reversible encephalopathy syndrome may also warrant ICU admission. This review will cover assessment of high-risk complications and management strategies following kidney transplantation.

RECENT FINDINGS

For intensivists caring for KTRs, it is imperative to understand anatomical considerations of the transplanted kidney, unique infectious risks faced by this population, and appropriate modulation of immunosuppression.

SUMMARY

Recognizing potential complications and implementing appropriate management strategies for KTRs admitted to the ICU will improve kidney allograft and patient survival outcomes.

Acute Kidney Injury in Kidney Transplant Patients in Intensive Care Unit: From Pathogenesis to Clinical Management

Kidney transplantation is the first-choice treatment for end-stage renal disease (ESRD). Kidney transplant recipients (KTRs) are at higher risk of experiencing a life-threatening event requiring intensive care unit (ICU) admission, mainly in the late post-transplant period (more than 6 months after transplantation). Urosepsis and bloodstream infections account for almost half of ICU admissions in this population; in addition, potential side effects related to immunosuppressive treatment should be accounted for cytotoxic and ischemic changes induced by calcineurin inhibitor (CNI), sirolimus/CNI-induced thrombotic microangiopathy and posterior reversible encephalopathy syndrome. Throughout the ICU stay, Acute Kidney Injury (AKI) incidence is common and ranges from 10% to 80%, and up to 40% will require renal replacement therapy. In-hospital mortality can reach 30% and correlates with acute illness severity and admission diagnosis. Graft survival is subordinated to baseline estimated glomerular filtration rate (eGFR), clinical presentation, disease severity and potential drug nephrotoxicity. The present review aims to define the impact of AKI events on short- and long-term outcomes in KTRs, focusing on the epidemiologic data regarding AKI incidence in this subpopulation; the pathophysiological mechanisms underlying AKI development and potential AKI biomarkers in kidney transplantation, graft and patients' outcomes; the current diagnostic work up and management of AKI; and the modulation of immunosuppression in ICU-admitted KTRs.

Hospitalisation Due to Community-Acquired Acute Kidney Injury and the Role of Medications: A Retrospective Audit

The aim of this study is to assess the use of high-risk medications in patients with community-acquired acute kidney injury (CA-AKI) and the differences in the characteristics and outcomes of CA-AKI based on the use of these medications. This is a retrospective audit of adults (≥35 years) with CA-AKI admitted to a large tertiary care hospital over a two-year period. We investigated the prevalence of SADMANS (sulfonylureas; angiotensin converting enzyme inhibitors; diuretics; metformin; angiotensin receptor blockers; nonsteroidal anti-inflammatory drugs; and sodium glucose co-transporter 2 inhibitors) medications use in people with CA-AKI prior to hospitalisation. Outcomes including CA-AKI severity, kidney function recovery and in-hospital mortality were examined and stratified by use of SADMANS medications. The study included 329 patients, with a mean (SD) age of 75 (12) years and a 52% proportion of females, who were hospitalised with CA-AKI. Most patients (77.5%) were taking at least one regular SADMANS medication upon admission. Overall, 40% of patients (n = 132) and 41% of those on SADMANS (n = 104) had hypovolaemia or associated symptoms such as vomiting and diarrhoea during admission. Over two-thirds (68.1%) had mild AKI on admission and patients who were taking SADMANS medications were more likely to have mild AKI. Patients on SADMANS had more comorbidities and a higher medication burden, but there were no differences in AKI severity on admission or outcomes such as length of hospitalisation, ICU admission, need for dialysis, recovery rates and mortality between the two groups. However, the high prevalence of SADMANS medications use among patients with CA-AKI indicates a potential for preventability of CA-AKI-led hospitalisations. Future studies are needed to gain better insights into the role of withholding this group of medications, especially during an acute illness.

Predictors and Adverse Outcomes of Acute Kidney Injury in Hospitalized Renal Transplant Recipients

Data about in-hospital AKI in RTRs is lacking. We conducted a retrospective study of 292 RTRs, with 807 hospital admissions, to reveal predictors and outcomes of AKI during admission. In-hospital AKI developed in 149 patients (51%). AKI in a previous admission was associated with a more than twofold increased risk of AKI in subsequent admissions (OR 2.13, p < 0.001). Other major significant predictors for in-hospital AKI included an infection as the major admission diagnosis (OR 2.93, p = 0.015), a medical history of hypertension (OR 1.91, p = 0.027), minimum systolic blood pressure (OR 0.98, p = 0.002), maximum tacrolimus trough level (OR 1.08, p = 0.005), hemoglobin level (OR 0.9, p = 0.016) and albumin level (OR 0.51, p = 0.025) during admission. Compared to admissions with no AKI, admissions with AKI were associated with longer length of stay (median time of 3.83 vs. 7.01 days, p < 0.001). In-hospital AKI was associated with higher rates of mortality during admission, almost doubled odds for rehospitalization within 90 days from discharge and increased the risk of overall mortality in multivariable mixed effect models. In-hospital AKI is common and is associated with poor short- and long-term outcomes. Strategies to prevent AKI during admission in RTRs should be implemented to reduce re-admission rates and improve patient survival.

Management of Hospitalized Kidney Transplant Recipients for Hospitalists and Internists

The number of kidney transplant recipients has grown incrementally over the years. These patients have a high comorbidity index and require special attention to immunosuppression management. In addition, this population has an increased risk for cardiovascular events, electrolyte abnormalities, allograft dysfunction, and infectious complications. It is vital for hospitalists and internists to understand the risks and nuances in the care of this increasingly prevalent, but also high-risk, population.

Acute kidney injury secondary to urinary tract infection in kidney transplant recipients

Acute kidney injury (AKI) in kidney transplant recipients (KTRs) is a common, yet poorly investigated, complication of urinary tract infections (UTI) and urosepsis. A retrospective comparative analysis was performed, recruiting 101 KTRs with urosepsis, 100 KTRs with UTI, and 100 KTRs without history of UTI or sepsis. The incidences of AKI in the urosepsis and UTI groups were 75.2% and 41%, respectively. The urosepsis group has also presented with a significantly higher prevalence of AKI stage 2 and 3 than the UTI group. The rates of recovery from AKI stages 1, 2 and 3, were 75,6%, 55% and 26.1%, respectively. Factors independently associated with renal recovery from AKI were: AKI severity grade (AKI stage 2 with OR = 0.25 and AKI stage 3 with OR = 0.1), transfusion of red blood cells (RBC) (OR = 0.22), and the use of steroid bolus in the acute phase of treatment (OR = 4). The septic status (urosepsis vs UTI) did not influence the rates of renal recovery from AKI after adjustment for the remaining variables. The dominant cause of RBC transfusions in the whole population was upper GI-bleeding. In multivariable analyses, the occurrence of AKI was also independently associated with a greater decline of eGFR at 1-year post-discharge and with a greater risk of graft loss. In KTRs with both urosepsis and UTI, the occurrence of AKI portends poor transplantation outcomes. The local transfusion policy, modulation of immunosuppression and stress ulcer prophylaxis (which is not routinely administered in KTRs) in the acute setting may be modifiable factors that significantly impact long-term transplantation outcomes.

Acute kidney injury after hip fracture in organ transplant recipients

BACKGROUND

This study aimed to investigate the incidence and risk factors of acute kidney injury (AKI) after hip fracture in organ transplant recipients.

METHODS

In this single-center retrospective cohort study, 795 elderly patients who underwent hip fracture surgery were enrolled. AKI was defined according to Acute Kidney Injury Network criteria. Among the 795 patients, 23 underwent kidney transplantation (KT) and 20 underwent liver transplantation (LT). The incidence of AKI, dialysis requirement, and renal recovery rate were investigated.

RESULTS

AKI occurred in 83 patients (10.5%), of whom 9 (39.1%), 3 (15%), and 71 (9.5%) were in the KT, LT, and non-transplantation groups, respectively. The incidence rates of AKI and severe AKI (17.4% vs. 1.4%) were significantly higher in the KT group than in the non-transplantation group (p = 0.001 for both). The renal recovery rate was significantly lower in the KT group than in the non-transplantation group (p = 0.033). The multivariate analysis revealed that male; body mass index; CKD; alkaline phosphatase; intraoperative hypotension; and history of KT were independent predictors of AKI development.

CONCLUSIONS

AKI and severe AKI after hip fracture occurred more frequently in the KT recipients with lower renal recovery rates. Transplanted kidneys are more vulnerable to AKI after hip fracture. This article is protected by copyright. All rights reserved.

Incidence of Mortality, Acute Kidney Injury and Graft Loss in Adult Kidney Transplant Recipients with Coronavirus Disease 2019: Systematic Review and Meta-Analysis

The adverse impact of Coronavirus disease 2019 (COVID-19) on kidney function has been reported since the global pandemic. The burden of COVID-19 on kidney transplant recipients, however, has not been systematically analyzed. A systematic review and meta-analysis with a random-effect model was conducted to explore the rate of mortality, intensive care unit admission, invasive mechanical ventilation, acute kidney injury, kidney replacement therapy and graft loss in the adult kidney transplant population with COVID-19. Sensitivity analysis, subgroup analysis and meta-regression were also performed. Results: we demonstrated a pooled mortality rate of 21% (95% CI: 19−23%), an intensive care unit admission rate of 26% (95% CI: 22–31%), an invasive ventilation rate among those who required intensive care unit care of 72% (95% CI: 62–81%), an acute kidney injury rate of 44% (95% CI: 39–49%), a kidney replacement therapy rate of 12% (95% CI: 9–15%), and a graft loss rate of 8% (95% CI: 5–15%) in kidney transplant recipients with COVID-19. The meta-regression indicated that advancing age is associated with higher mortality; every increase in age by 10 years was associated with an increased mortality rate of 3.7%. Regional differences in outcome were also detected. Further studies focused on treatments and risk factor identification are needed.

Chemotherapy, targeted therapy and immunotherapy: Which drugs can be safely used in the solid organ transplant recipients?

In solid organ transplant recipients, cancer is associated with worse prognosis than in the general population. Among the causes of increased cancer‐associated mortality, are the limitations in selecting the optimal anticancer regimen in solid organ transplant recipients, because of the associated risks of graft toxicity and rejection, drug‐to‐drug interactions, reduced kidney or liver function, and patient frailty and comorbid conditions. The advent of immunotherapy has generated further challenges, mainly because checkpoint inhibitors increase the risk of rejection, which may have life‐threatening consequences in recipients of life‐saving organs. In general, there are no safe or unsafe anticancer drugs. Rather, the optimal choice of the anticancer regimen results from a careful risk/benefit assessment, from the awareness of potential pharmacokinetic and pharmacodynamic drug‐to‐drug interactions, and of the risk of drug overexposure in patients with kidney or liver dysfunction. In this review, we summarize general principles that may help the oncologists and transplant physicians in the multidisciplinary management of recipients of solid organ transplantation with cancer who are candidates for chemotherapy, targeted therapy, or immunotherapy.

The Impact of Rivaroxaban and Apixaban on Tacrolimus Trough Levels

The solid organ transplant community is slow to adopt the routine practice of using direct oral anticoagulants. Rivaroxaban and apixaban share common metabolic pathways with tacrolimus. This study aimed to clarify the impact of rivaroxaban/apixaban on tacrolimus troughs. Fifty solid organ transplant recipients with concomitant use of tacrolimus and rivaroxaban/apixaban were retrospectively assessed for changes in tacrolimus troughs and dose. Average dose-adjusted tacrolimus troughs and average tacrolimus total daily doses prior to and after rivaroxaban/apixaban initiation were compared. Subgroup analyses evaluating rivaroxaban and apixaban individually were performed. Rivaroxaban was prescribed to 18 recipients, and apixaban was prescribed to 32 recipients. Transplanted organs included kidney (n = 22), lung (n = 18), liver (n = 7), simultaneous pancreas and kidney (n = 1), and simultaneous kidney and liver (n = 2). The median doseadjusted tacrolimus trough and tacrolimus total daily dose prior to rivaroxaban/apixaban initiation was 2.15 ng/mL/mg (IQR 1.17, 3.37) and 4 mg (IQR 1.88, 6.25), respectively. The median dose-adjusted tacrolimus trough and tacrolimus total daily dose after rivaroxaban/apixaban initiation was 2.16 ng/mL/mg (IQR 1.24, 4.10) and 3.55 mg (IQR 1.5, 6.35), respectively. No significant difference was found between average dose-adjusted tacrolimus troughs or tacrolimus total daily doses before and after rivaroxaban/apixaban initiation or in the individual subgroup analyses for rivaroxaban/apixaban. It is unlikely that initiating rivaroxaban/apixaban affects tacrolimus troughs or requires tacrolimus dose adjustment. This study does not elucidate if tacrolimus affects rivaroxaban/apixaban pharmacokinetics or pharmacodynamics.

Acute Kidney Injury (AKI) before and after Kidney Transplantation: Causes, Medical Approach, and Implications for the Long-Term Outcomes

Acute kidney injury (AKI) is a common finding in kidney donors and recipients. AKI in kidney donor, which increases the risk of delayed graft function (DGF), may not by itself jeopardize the short- and long-term outcome of transplantation. However, some forms of AKI may induce graft rejection, fibrosis, and eventually graft dysfunction. Therefore, various strategies have been proposed to identify conditions at highest risk of AKI-induced DGF, that can be treated by targeting the donor, the recipient, or even the graft itself with the use of perfusion machines. AKI that occurs early post-transplant after a period of initial recovery of graft function may reflect serious and often occult systemic complications that may require prompt intervention to prevent graft loss. AKI that develops long after transplantation is often related to nephrotoxic drug reactions. In symptomatic patients, AKI is usually associated with various systemic medical complications and could represent a risk of mortality. Electronic systems have been developed to alert transplant physicians that AKI has occurred in a transplant recipient during long-term outpatient follow-up. Herein, we will review most recent understandings of pathophysiology, diagnosis, therapeutic approach, and short- and long-term consequences of AKI occurring in both the donor and in the kidney transplant recipient.

Acute kidney injury in renal transplant recipients undergoing cardiac surgery

BACKGROUND

Acute kidney injury (AKI) is a key risk factor for chronic kidney disease in the general population, but has not been investigated in detail among renal transplant recipients (RTRs). We investigated the incidence, severity and risk factors for AKI following cardiac surgery among RTRs compared with non-RTRs with otherwise similar clinical characteristics.

METHODS

We conducted a retrospective cohort study of RTRs (n = 83) and non-RTRs (n = 83) who underwent cardiac surgery at two major academic medical centers. Non-RTRs were matched 1:1 to RTRs by age, preoperative (preop) estimated glomerular filtration rate and type of cardiac surgery. We defined AKI according to Kidney Disease: Improving Global Outcomes criteria.

RESULTS

RTRs had a higher rate of AKI following cardiac surgery compared with non-RTRs [46% versus 28%; adjusted odds ratio 2.77 (95% confidence interval 1.36-5.64)]. Among RTRs, deceased donor (DD) versus living donor (LD) status, as well as higher versus lower preop calcineurin inhibitor (CNI) trough levels, were associated with higher rates of AKI (57% versus 33% among DD-RTRs versus LD-RTRs; P = 0.047; 73% versus 36% among RTRs with higher versus lower CNI trough levels, P = 0.02). The combination of both risk factors (DD status and higher CNI trough level) had an additive effect (88% AKI incidence among patients with both risk factors versus 25% incidence among RTRs with neither risk factor, P = 0.004).

CONCLUSIONS

RTRs have a higher risk of AKI following cardiac surgery compared with non-RTRs with otherwise similar characteristics. Among RTRs, DD-RTRs and those with higher preop CNI trough levels are at the highest risk.

Using electronic AKI alerts to define the epidemiology of acute kidney injury in renal transplants

Background

Little is known regarding the impact of acute kidney injury (AKI) on renal transplant outcome. Our aim was to define the incidence and outcome of AKI in renal transplant patients using data collected from a national AKI electronic alert system

Methods

The study represents a prospective national cohort study collecting data on 1224 renal transplants recipients with a functioning renal transplant, between April 2015 and March 2019.

Results

Four hundred forty patients experienced at least one episode of AKI giving an incidence rate of 35.4%. Sixty-four point seven% of episodes were AKI stage 1, 7.3% AKI stage 2 and 28% AKI stage 3. Only 6.2% of episodes occurred in the context of rejection. Forty-three point five% of AKI episodes were associated with sepsis. AKI was associated with pre-existing renal dysfunction, and a primary renal diagnosis of diabetic nephropathy. AKI was more prevalent in recipients from a donor after cardiac death (26.4% vs. 21.4%, p < 0.05) compared to the non-AKI cohort. Following AKI, 30-day mortality was 19.8% and overall mortality was 34.8%, compared to 8.4% in the non AKI cohort (RR 4.06, 95% CI 3.1–5.3, p < 0.001). Graft survival (GS), and death censored graft survival (DCGS) censored at 4 years, in the AKI cohort were significantly lower than in the non AKI group (p < 0.0001 for GS and DCGS).

Conclusion

The study provides a detailed characterisation of AKI in renal transplant recipients highlighting its significant negative impact on patient and graft survival.

Long-term Assessment of NSAID Prescriptions and Potential Nephrotoxicity Risk in Adult Kidney Transplant Recipients

BACKGROUND

Nonsteroidal anti-inflammatory drug (NSAID) use is recommended to be avoided in kidney transplantation, with a paucity of studies assessing their safety within this population. This study aims to use a large cohort of Veterans Affairs (VA) kidney transplantation recipients to assess the risk of acute kidney injury (AKI) with NSAID use.

METHODS

This is a 10-year longitudinal cohort study of adult kidney transplant recipients retrospectively followed in the VA system from 2001 to 2010 that assessed for risk of AKI with NSAID prescriptions. NSAID prescriptions, patient characteristics, and estimated glomerular filtration rates were abstracted from the VA comprehensive electronic health record. NSAID exposure was assessed by duration, dosage, and type. AKI events were defined by ≥50% decrease in estimated glomerular filtration rate. Risk was estimated using longitudinal multivariable generalized logistic regression model.

RESULTS

About 5100 patients were included with a total of 29 980 years of follow-up; 671 NSAID prescriptions in 273 (5.4%) patients (2.24 per 100 patient-y) with 472 (70%) high dose were identified. High-dose NSAID prescriptions were associated with 2.83 (95% confidence interval [CI], 1.55-5.19; P < 0.001) higher odds of AKI events within a given year; low dose was not associated with AKI (odds ratio, 1.93; 95 % CI, 0.95-6.02; P = 0.256). One 7-day NSAID course was associated with 5% higher odds of increasing AKI events, whereas chronic use (≥180 d) was associated with 3.25 (95% CI, 1.78-5.97; P < 0.001) higher odds of AKI.

CONCLUSIONS

Prescriptions for NSAIDs were uncommon in this cohort but were associated with a significant increase in the risk of AKI, which was impacted by higher NSAID dose and longer NSAID durations.

Acute Kidney Injury in Hospitalized Kidney Transplant Recipients

BACKGROUND

Acute kidney injury (AKI) is a main cause of morbidity, hospitalization, and hospital readmission in kidney transplant recipients. We aimed to determine AKI incidence and risk factors following kidney transplant to assess outcomes such as renal function and graft loss after AKI.

METHODS

We conducted a retrospective cohort study with hospitalized kidney transplant recipients during 2016 to 2017. Clinical data of 179 patients were reviewed. The primary outcome was AKI incidence and risk factors. To determine AKI occurrence, we based it on creatinine criteria from Acute Kidney Injury Network classification.

RESULTS

We documented a total of 179 hospital admissions; AKI was diagnosed in 104 patients (58.1%). Recipients with higher baseline serum creatinine (odds ratio, 2.6; confidence interval [CI], 1.5-4.5; P < .001) and hospital admission because of infections (odds ratio, 2.4; CI, 1.1-5.2; P = .020) were more likely to experience AKI. A total of 19 recipients (10.6%) had graft loss with a significant AKI association (P = .003) at 12 months after admission. Intensive care unit length of stay (P = .63) and hospital stay (P = .55) were not different in patients with AKI compared with the control group.

CONCLUSIONS

As a main clinical finding, we concluded that infections and higher serum creatinine baseline level were associated with the development of AKI.

MRI for diagnosis of post-renal transplant complications: current state-of-the-art and future perspectives

Kidney transplantation has developed into a widespread procedure to treat end stage renal failure, with transplantation results improving over the years. Postoperative complications have decreased over the past decades, but are still an important cause of morbidity and mortality. Early accurate diagnosis and treatment is the key to prevent renal allograft impairment or even graft loss. Ideally, a diagnostic tool should be able to detect post-transplant renal dysfunction, differentiate between the different causes and monitor renal function during and after therapeutic interventions. Non-invasive imaging modalities for diagnostic purposes show promising results. Magnetic resonance imaging (MRI) techniques have a number of advantages, such as the lack of ionizing radiation and the possibility to obtain relevant tissue information without contrast, reducing the risk of contrast-induced nephrotoxicity. However, most techniques still lack the specificity to distinguish different types of parenchymal diseases. Despite some promising outcomes, MRI is still barely used in the post-transplantation diagnostic process. The aim of this review is to survey the current literature on the relevance and clinical applicability of diagnostic MRI modalities for the detection of various types of complications after kidney transplantation.

Hospitalization Trends for Acute Kidney Injury in Kidney Transplant Recipients in the United States, 2004-2014

BACKGROUND

The incidence of acute kidney injury (AKI) and AKI requiring dialysis (AKI-D) in the general population is increasing. However, there is limited information on the epidemiology of AKI-related hospitalizations in the prevalent US kidney transplant population.

METHODS

We analyzed trends in the incidence of hospitalizations with primary diagnosis of AKI and secondary diagnosis of AKI and AKI-D using data from the National Inpatient Sample 2004-2014. Co-primary endpoints were in-hospital mortality, length of stay (LOS), and cost. Survey analysis techniques were used to compute national estimates. Linear trends in outcomes were evaluated using linear regression.

RESULTS

There were a total of 37 562 hospitalizations for primary AKI, 136 628 for secondary AKI, and 10 731 for AKI-D during the study period. We found an increase in hospitalizations for all 3 diagnoses over time (13.7-24.7 per thousand kidney transplant recipients [KTRs] for primary AKI, 37.4-108.0 per thousand KTRs for secondary AKI, and 4.2-6.0 per thousand KTRs for AKI-D; all P trend < 0.01). This was accompanied by significant improvements in in-hospital mortality (3.2%-0.5% for primary and 6.1%-4.4% for secondary AKI; both P trend < 0.01), average LOS (5.3-4.6 days for primary and 8.4-7.2 days for secondary AKI; both P trend < 0.001), and cost ($11 635-$8234 for primary and $21 373-$17 470 for secondary AKI; P trend < 0.001 for both).

CONCLUSIONS

The incidence of hospitalizations for AKI and AKI-D among KTRs is rapidly rising. This has been accompanied by significant improvements in in-hospital mortality, LOS, and cost.

Acute Kidney Injury and Long-Term Risk for Cardiovascular Events in Patients after Kidney Transplantation

BACKGROUND

Acute kidney injury (AKI) was found to be associated with an increased risk of major adverse cardiovascular events (MACE) in the general population. Patients after kidney transplantation are prone to AKI events and are also at an increased risk of cardiovascular (CV) disease. The association between AKI and MACE in kidney transplant patients is yet to be studied.

METHODS

This retrospective single-center cohort study reviewed 416 adult renal allograft recipients transplanted between 2005 and 2010. AKI events were recorded starting 2 weeks after transplantation, or following discharge with a functioning graft. AKI was defined, according to the KDIGO criteria. The primary outcome was the composite of MACE starting 6 months after transplantation and all-cause mortality. For survival analysis, we used univariate and multivariate time varying Cox proportional hazard model.

RESULTS

One hundred and twenty-four patients (29.8%) had at least one episode of AKI. During the median follow-up time of 7.2 years (interquartile range 4.3-9.1), 144 outcome events occurred. By time varying Cox regression analysis, AKI was associated with an increased rate of CV outcomes or death (hazard ratio [HR] 1.96, 95% CI 1.36-2.81, p < 0.001), and the association remained significant by multivariate adjusted model (HR 1.76, 95% CI 1.18-2.63, p = 0.005). As for the different components of MACE, all-cause mortality and CV mortality were the only outcomes that were significantly associated with AKI. No interaction between AKI timing and MACE was found.

CONCLUSION

AKI in kidney transplant recipient is associated with an increased risk of CV disease.

A prospective study of clinical characteristics and outcomes of acute kidney injury in a tertiary care Centre

Background

Acute kidney injury (AKI) is a major global health problem. We aim to evaluate the epidemiology, risk factors and outcomes of AKI episodes in our single centre.

Methodology

We prospectively identified 422 AKI and acute on chronic kidney disease episodes in 404 patients meeting KDIGO definitions using electronic medical records and clinical data from 15th July to 22nd October 2016, excluding patients with baseline estimated GFR (eGFR) of < 15 mL/min. Patients were followed up till 6 months after AKI diagnosis.

Results

The mean age was 65.8 ± 14.1. Majority of patients were male (58.2%) of Chinese ethnicity (68.8%). One hundred and thirty-two patients (32.6%) were diagnosed in acute care units. Seventy-five percent of patients developed AKI during admission in a non-Renal specialty. Mean baseline eGFR was 50.2 ± 27.7 mL/min. Mean creatinine at AKI diagnosis was 297 ± 161 μmol/L. Renal consultations were initiated at KDIGO Stages 1, 2 and 3 in 58.9, 24.5 and 16.6% of patients, respectively. Three hundred and ten (76.7%) patients had a single etiology of AKI with the 3 most common etiologies of AKI being pre-renal (27.7%), sepsis-associated (25.5%) and ischemic acute tubular necrosis (15.3%). One hundred and nine (27%) patients received acute renal replacement therapy. In-hospital mortality was 20.3%. Six-month mortality post-AKI event was 9.4%. On survival analysis, patients with KDIGO Stage 3 AKI had significantly shorter survival than other stages.

Conclusion

AKI is associated with significant in-hospital to 6-month mortality. This signifies the pressing need for AKI prevention, early detection and intervention in mitigating reversible risk factors in order to optimize clinical outcomes.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1466-z) contains supplementary material, which is available to authorized users.

Outcomes of kidney transplant recipients admitted to the intensive care unit: a retrospective study of 200 patients

Background

Risk of over-immunosuppression or immunization may mitigate the overall and long-term renal outcomes of kidney transplant recipients (KTR) admitted to the ICU in the modern era but remain poorly described. Thus, there is an unmet need to better characterize the survival of KTR admitted to the ICU, but also the renal and immunological outcomes of survivors.

Methods

Retrospective observational study that included 200 KTR admitted between 2010 and 2016 to the ICU of a teaching hospital (median age 61 years [IQR 50.7–68]; time from transplantation 41 months [IQR 5–119]). Survival curves were compared using the Log-rank test.

Results

Mortality rates following admission to the ICU was low (26.5% at month-6), mainly related to early mortality (20% in-hospital), and predicted by the severity of the acute condition (SAPS2 score) but also by Epstein Barr Virus proliferation in the weeks preceding the admission to the ICU. Acute kidney injury (AKI) was highly prevalent (85.1%). Progression toward chronic kidney disease (CKD) was observed in 45.1% of survivors. 15.1% of survivors developed new anti-HLA antibodies (donor-specific antibodies 9.2% of cases) that may impact the long-term renal transplantation function.

Conclusions

Notwithstanding the potential biases related to the retrospective and monocentric nature of this study, our findings obtained in a large cohort of KTR suggest that survival of KTR admitted in ICU is good but in-ICU management of these patients may alter both survival and AKI to CKD transition, as well as HLA immunization. Further interventional studies, including systematic characterization of the Epstein Barr virus proliferation at the admission (i.e., a potential surrogate marker of an underlying immune paralysis and frailty) will need to address the optimal management of immunosuppressive regimen in ICU to improve survival but also renal and immunological outcomes.

Non-invasive differentiation of non-rejection kidney injury from acute rejection in pediatric renal transplant recipients

Acute kidney injury (AKI) is a major concern in pediatric kidney transplant recipients, where non-alloimmune causes must be distinguished from rejection. We sought to identify a urinary metabolite signature associated with non-rejection kidney injury (NRKI) in pediatric kidney transplant recipients. Urine samples (n = 396) from 60 pediatric transplant participants were obtained at time of kidney biopsy and quantitatively assayed for 133 metabolites by mass spectrometry. Metabolite profiles were analyzed via projection on latent structures discriminant analysis. Mixed-effects regression identified laboratory and clinical predictors of NRKI and distinguished NRKI from T cell-mediated rejection (CMR), antibody-mediated rejection (AMR), and mixed CMR/AMR. Urine samples (n = 199) without rejection were split into NRKI (n = 26; ΔSCr ≥25%), pre-NRKI (n = 35; ΔSCr ≥10% and <25%), and no NRKI (n = 138; ΔSCr <10%) groups. The NRKI discriminant score (dscore) distinguished between NRKI and no NRKI (AUC = 0.86; 95% CI = 0.79-0.94), confirmed by leave-one-out cross-validation (AUC = 0.79; 95% CI = 0.68-0.89). The NRKI dscore also distinguished between NRKI and pre-NRKI (AUC = 0.82; 95% CI = 0.71-0.93). In a linear mixed-effects regression model to account for repeated measures, the NRKI dscore was independent of concurrent rejection, but there was a non-statistical trend for higher dscores with rejection severity. A second exploratory classifier developed to distinguish NRKI from clinical rejection had similar test characteristics (AUC = 0.81, 95% CI = 0.70-0.92, confirmed by LOOCV). This study demonstrates the potential of a urine metabolite classifier to detect NRKI in pediatric kidney transplant patients and non-invasively discriminate NRKI from rejection.

Acute Kidney Injury in Children with Kidney Transplantation

BACKGROUND AND OBJECTIVES

AKI is associated with progression of CKD. Little is known about AKI after kidney transplantation in pediatric recipients. We aim to describe the epidemiology, risk factors, consequences, and outcomes of AKI in this population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a retrospective longitudinal analysis of pediatric kidney transplant recipients followed at The Hospital for Sick Children (Toronto, Canada) from 2001 to 2012. AKI was defined as an increase in serum creatinine ≥1.5 times baseline, and a rise of serum creatinine ≥1.25 but <1.5 times baseline defined subacute AKI.

RESULTS

Of 179 children, 122 were eligible for analysis. At baseline (3 months post-transplant), median age of the children was 13 years old (interquartile range, 9-16 years old), and 53% had CKD stage 2. Congenital anomalies of the kidney and urinary tract accounted for 46% of children. Over the study period (12 years), the incidence of AKI was 37% (n=45 children), and 65% (79 children) experienced subacute AKI. Twenty-seven percent (33 children) did not develop AKI or subacute AKI. The main causes of AKI were infections other than urinary tract infections, rejection, and urinary tract infections. In a multivariable Poisson regression analysis, independent risk factors for AKI included younger age, girls, grafts from deceased donors, and lower baseline eGFR. AKI was significantly associated with lower long-term GFR and graft loss independent of rejection episodes. Moreover, subacute AKI was associated with progression of CKD.

CONCLUSIONS

AKI and subacute AKI were common after pediatric kidney transplantation, and they were associated with graft loss, lower eGFR, and more rapid progression of CKD.

Diagnostic value of plasma tryptophan and symmetric dimethylarginine levels for acute kidney injury among tacrolimus-treated kidney transplant patients by targeted metabolomics analysis

Few literatures have evaluated the exact role of metabolomics in the identification process of potential biomarkers for acute kidney injury among the patients receiving renal transplantation. On top of this, the success of metabolomics in biomarker translation seems to lie in the robust quantitative method. As such, a single-center retrospective observational study was conducted enrolling 42 patients underwent renal transplantation with/without acute kidney injury, as well as 24 healthy volunteers, in Shanghai Changzheng Hospital. Plasma amino acid metabolic patterns for the participants were investigated by targeted UHPLC-MS/MS metabolic profiling. The most significant changes of the explored metabolites were related to the disturbance of tryptophan metabolism and arginine metabolism. Abnormal circulating tryptophan and symmetric dimethylarginine were identified to be potential biomarkers of acute kidney injury, combination of which showed a higher area under receiver-operator curve value (AUC = 0.901), improved sensitivity (0.889) and specificity (0.831) compared with creatinine only. Overall, these results revealed that targeted metabolomics analysis would be a potent and promising strategy for identification and pre-validation of biomarkers of acute kidney injury in renal transplantation patients.

De Novo Postinfectious Glomerulonephritis Secondary to Nephritogenic Streptococci as the Cause of Transplant Acute Kidney Injury: A Case Report and Review of the Literature

Acute kidney injury is common among kidney transplant recipients. Postinfectious glomerulonephritis secondary to nephritogenic streptococci is one of the oldest known etiologies of acute kidney injury in native kidneys but rarely reported among kidney transplant recipients. This report is of a biopsy-proven case of acute kidney injury in a renal allograft recipient caused by de novo poststreptococcal glomerulonephritis.

Ischemic acute kidney injury and klotho in renal transplantation

Post-transplant ischemic acute kidney injury (AKI), secondary to ischemia reperfusion injury (IRI), is a major problem influencing on the short and long term graft and patient survival. Many molecular and cellular modifications are observed during IRI, for example, tissue damage result production of reactive oxygen species (ROS), cytokines, chemokines, and leukocytes recruitment which are activated by NF-κB (nuclear factor kappa B) signaling pathway. Therefore, inhibiting these processes can significantly protect renal parenchyma from tissue damage. Klotho protein, mainly produced in distal convoluted tubules (DCT), is an anti-senescence protein. There is increasing evidence to confirm a relationship between Klotho levels and renal allograft function. Many studies have also demonstrated that expression of the Klotho gene would be down regulated with IRI, so it will be used as an early biomarker for acute kidney injury after renal transplantation. Other studies suggest that Klotho may have a renoprotective effect for attenuating of kidney injury. In this review, we will discuss pathophysiology of IRI-induced acute kidney injury and its relation with klotho level in renal transplantation procedure.

Effects of different storage solutions on renal ischemia tolerance after kidney transplantation in mice

storage is the most prevalent method for graft preservation in kidney transplantation (KTX). The protective effects of various preservation solutions have been studied extensively in both clinical trials and experimental animal models. However, a paucity of studies have examined the effect of different preservation solutions on graft function in mouse KTX; in addition, the tolerance of the transplanted grafts to further insult has not been evaluated, which was the objective of the present study. We performed mouse KTX in three groups, with the donor kidneys preserved in different solutions for 60 min: saline, mouse serum, and University of Wisconsin (UW) solution. The graft functions were assessed by kidney injury markers and glomerular filtration rate (GFR). The grafts that were preserved in UW solution exhibited better functions, reflected by 50 and 70% lower plasma creatinine levels as well as 30 and 55% higher plasma creatinine levels in GFR than serum and saline groups, respectively, during the first week after transplants. To examine the graft function in response to additional insult, we induced ischemia-reperfusion injury (IRI) by clamping the renal pedicle for 18 min at 4 wk after KTX. We found that the grafts preserved in UW solution exhibited ~30 and 20% less injury assessed by kidney injury markers and histology than in other two preservation solutions. Taken together, our results demonstrated that UW solution exhibited a better protective effect in transplanted renal grafts in mice. UW solution is recommended for use in mouse KTX for reducing confounding factors such as IRI during surgery.

Impact of acute kidney injury on renal allograft survival

BACKGROUND

Acute kidney injury (AKI) is one of the major determinants of graft survival in kidney transplantation (KTx). Renal Transplant recipients are more vulnerable to develop AKI than general population. AKI in the transplant recipient differs from community acquired, in terms of risk factors, etiology and outcome. Our aim was to study the incidence, risk factors, etiology, outcome and the impact of AKI on graft survival.

METHODS

A retrospective analysis of 219 renal transplant recipients (both live and deceased donor) was done.

RESULTS

AKI was observed in 112 (51.14%) recipients, with mean age of 41.5 ± 11.2 years during follow-up of 43.2 ± 12.5 months. Etiologies of AKI were infection (47.32%), rejection (26.78%), calcineurin inhibitor (CNI) toxicity (13.39%), and recurrence of native kidney disease (NKD) (4.46%). New Onset Diabetes After Transplant (NODAT) and deceased donor transplant were the significant risk factors for AKI. During follow-up 70.53% (p = .004) of AKI recipients progressed to chronic kidney disease (CKD) in contrast to only 11.21% (p = .342) of non AKI recipients. Risk factors for CKD were AKI within first year of transplant (HR: 7.32, 95%CI: 4.37-15.32, p = .007), multiple episodes of AKI (HR: 6.92, 95%CI: 3.92-9.63, p = .008), infection (HR: 3.62, 95%CI: 2.8-5.75, p = .03) and rejection (HR: 9.92 95%CI: 5.56-12.36, p = .001).

CONCLUSION

Renal transplant recipients have high risk for AKI and it hampers long-term graft survival.

A Mayo Clinic 13-year investigation of the syndrome of rapid onset ESRD among renal transplant recipients: An analysis of the implications of renal allograft biopsy results

INTRODUCTION

We first described the syndrome of rapid onset end stage renal disease (SORO-ESRD), acute yet irreversible renal failure, in 2010.

OBJECTIVE

The impact of SORO-ESRD renal allograft survival remains speculative and we plan to study this question.

METHODS

A retrospective analysis of individual adult patient-level serum creatinine trajectories of ESRD patients on maintenance hemodialysis for >90 days at Mayo Clinic, Rochester, 2001-2013.

RESULTS

Of 1461 ESRD patients, 149 (10%) patients including 13 renal transplant recipients (RTRs) satisfied the diagnosis of SORO-ESRD - 4 males, 9 females, 12 Caucasians/one other, age 45 (18-83) years. Serum creatinine was 1.4 (0.8-1.7) mg/dL in the last year before hemodialysis initiation. Initial hemodialysis access was a dialysis catheter in all 13 patients. AKI precipitating SORO-ESRD followed acute rejection (4), postoperative (2), tubulo-interstitial nephritis (2), unknown (2), infection/sepsis (1), contrast nephropathy (1), BKV nephropathy (1), and cardio-renal syndrome (1). Renal allograft survival was 1469 (277-4939) days (4 years). Renal allograft biopsies were available in 9/14 (69%) RTRs - Four showed acute rejection, two of which followed interruption of immunosuppression, three revealed acute tubular necrosis and four others also showed chronic transplant glomerulopathy. Time on hemodialysis was 856 (129-1630) days (2.4 years). 5/13 RTRs with SORO-ESRD (38%) died - 3 (60%) following cardiac arrest, 2 (40%) after stopping hemodialysis. 4/13 (31%) were re-transplanted in the period of this study.

CONCLUSION

SORO-ESRD contributed significantly to late renal allograft loss and return to hemodialysis with 100% initial dialysis catheter rate. Potentially preventable causes of AKI leading to SORO-ESRD were identified. The application of experience gained from such studies would help reduce late renal allograft loss and the need for re-transplantation. This would further help reduce the yawning gap between need and availability of donor kidney organs both here in the United States and around the world. Larger studies are warranted.

Comparison of the Frequency of Acute Kidney Injury in Patients With Renal Transplant Who Underwent Percutaneous Coronary Intervention Versus Coronary Artery Bypass Graft Surgery

Percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) are established modalities of coronary revascularization. Choosing between the two requires taking into consideration not only disease severity, patient characteristics, and expected outcomes but also adverse effects. One such adverse effect is acute kidney injury (AKI), especially when considering coronary revascularization in patients with renal transplant (RT). We searched the National Inpatient Sample from 2008 to 2014 using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for patients with RT (V42.0) who underwent PCI (00.66, 36.06, and 36.07) and CABG (36.1×, 36.2, and 36.3×). We further identified patients with AKI (584.5, 584.6, 584.7, 584.8, and 584.9) and those on dialysis (39.95). The propensity score model/method was used to form matched cohorts for PCI and CABG. We compared the incidence of AKI and AKI requiring dialysis in CABG and PCI groups. We identified 1,871 patients who underwent PCI and 1,878 patients who underwent CABG after propensity score matching. We found the incidence of both AKI (22% vs 38%, odds ratio 2.20, 95% confidence interval 1.91 to 2.54, p <0.0001) and AKI requiring dialysis (1% vs 3%, odds ratio 2.50, 95% confidence interval 1.49 to 4.19, p = 0.001) to be significantly higher in the CABG compared with the PCI cohort. In conclusion, the results of the study reflect the importance of accounting for the RT status before choosing between PCI and CABG for coronary revascularization.

[Acute kidney injury : A clinical syndrome]

Acute kidney injury (AKI) is a clinical syndrome occurring in the context of multiple and diverse disease entities. Although the term AKI implies renal damage as well as functional impairment or a combination of both, diagnosis is solely based on the functional parameters serum creatinine and urine output. Independent of the underlying disease and even assuming full recovery of renal function, AKI is associated with increased morbidity and mortality not only during the acute situation, but also long term. Awareness of the individual risk profile of each patient and the variety of causes and clinical manifestations of AKI is pivotal for prophylaxis, diagnosis, and therapy. The complexity of the clinical syndrome in the context of sepsis, solid organ transplantation, malignancy, and autoimmune diseases requires differentiated diagnostic and therapeutic approaches and interdisciplinary care.

Acute Kidney Injury in Transplant Setting: Differential Diagnosis and Impact on Health and Health Care

Acute kidney injury (AKI) is common in kidney transplant recipients. In addition to the usual causes of AKI in native kidneys, certain features and risk factors are unique to kidney allografts. In this article, we will present an overview of the common transplant-specific AKI etiologies that include increased susceptibility to hemodynamic-mediated AKI, acute rejection, medication-induced AKI, recurrence of native kidney disease, infections, urinary tract obstruction, vascular thrombosis and post-transplant lymphoproliferative disorder. AKI is independently associated with allograft loss and patient mortality. It is, therefore, prudent for transplant centers to address it as a major quality measure.

Supplementing diet with Manitoba lingonberry juice reduces kidney ischemia-reperfusion injury

BACKGROUND

Lingonberry (Vaccinium vitis-idaea L.) contains high levels of anthocyanins which are bioavailable in the kidney and may be protective against ischemia-reperfusion (IR)-induced acute kidney injury. This study investigated the effect of lingonberry juice on the IR-induced stress-activated signalling pathway and inflammatory response in the kidney.

RESULTS

Sprague-Dawley rats subjected to kidney IR had significantly impaired kidney function, with increased activation of the JNK signalling pathway and increased inflammatory response, measured using a multiplex panel containing an extensive array of inflammatory biomarkers. In rats fed 1 mL lingonberry juice daily for 3 weeks prior to IR, kidney function was protected and attenuation of inflammatory response and JNK signalling was reflected in the reduction of the measured biomarkers. In vitro results in cultured HK-2 cells confirmed that lingonberry anthocyanins reduced JNK signalling and inflammatory gene expression after IR.

CONCLUSION

This study shows, for the first time, that daily supplementation with lingonberry juice may protect against loss of kidney function induced by IR injury by modulating JNK signalling and inhibiting the subsequent inflammatory response. © 2017 Her Majesty the Queen in Right of Canada. Journal of the Science of Food and Agriculture © 2017 Society of Chemical Industry.

Derivation of a Predictive Model for Graft Loss Following Acute Kidney Injury in Kidney Transplant Recipients

Background:

Acute kidney injury (AKI) is common in the kidney transplant population.

Objective:

To derive a multivariable survival model that predicts time to graft loss following AKI.

Design:

Retrospective cohort study using health care administrative and laboratory databases.

Setting:

Southwestern Ontario (1999-2013) and Ottawa, Ontario, Canada (1996-2013).

Patients:

We included first-time kidney only transplant recipients who had a hospitalization with AKI 6 months or greater following transplant.

Measurements:

AKI was defined using the Acute Kidney Injury Network criteria (stage 1 or greater). The first episode of AKI was included in the analysis. Graft loss was defined by return to dialysis or repeat kidney transplant.

Methods:

We performed a competing risk survival regression analysis using the Fine and Gray method and modified the model into a simple point system. Graft loss with death as a competing event was the primary outcome of interest.

Results:

A total of 315 kidney transplant recipients who had a hospitalization with AKI 6 months or greater following transplant were included. The median (interquartile range) follow-up time was 6.7 (3.3-10.3) years. Graft loss occurred in 27.6% of the cohort. The final model included 6 variables associated with an increased risk of graft loss: younger age, increased severity of AKI, failure to recover from AKI, lower baseline estimated glomerular filtration rate, increased time from kidney transplant to AKI admission, and receipt of a kidney from a deceased donor. The risk score had a concordance probability of 0.75 (95% confidence interval [CI], 0.69-0.82). The predicted 5-year risk of graft loss fell within the 95% CI of the observed risk more than 95% of the time.

Limitations:

The CIs of the estimates were wide, and model overfitting is possible due to the limited sample size; the risk score requires validation to determine its clinical utility.

Conclusions:

Our prognostic risk score uses commonly available information to predict the risk of graft loss in kidney transplant patients hospitalized with AKI. If validated, this predictive model will allow clinicians to identify high-risk patients who may benefit from closer follow-up or targeted enrollment in future intervention trials designed to improve outcomes.

Validation of administrative database codes for acute kidney injury in kidney transplant recipients

Background

Validation studies of acute kidney injury (AKI) diagnostic codes performed in the general population have shown poor sensitivity, but the accuracy of such codes in the kidney transplant population remains unknown.

Objective

The objective of this study is to determine the accuracy of AKI diagnostic codes in kidney transplant recipients. We hypothesized that the sensitivity of diagnostic codes would be significantly greater in the kidney transplant population since these patients are closely followed by nephrologists and are more likely to have serum creatinine measured.

Design

The design is a population-based retrospective cohort study using healthcare administrative and laboratory databases.

Setting

The setting is in Southwestern Ontario and Ottawa, Ontario, Canada, from 2003 to 2012.

Patients

We included first-time kidney transplant recipients admitted to hospital for whom serum creatinine was measured in hospital and within 6 months prior (n = 524).

Methods

Patients meeting the Acute Kidney Injury Network (AKIN) classification serum creatinine change criteria were classified as having AKI. We determined the sensitivity, specificity, and negative and positive predictive values for the ICD-10-CA code for AKI when present as an admission diagnosis, most responsible diagnosis, or any diagnosis compared to a reference standard of AKI defined by the AKIN criteria (stage 1 or greater, stage 2 or greater, or stage 3).

Results

Forty-five percent of included kidney transplant patients had a diagnosis of AKI. The most sensitive coding algorithm (reference standard AKIN stage 2 or greater, ICD-10 code present as any diagnosis) had a sensitivity of 42.1 % (95 % CI 31.7, 53.3), a specificity of 90.6 % (95 % CI 87.6, 93.0), and a positive likelihood ratio of 4.5. The median (IQR) rise in serum creatinine from baseline in patients with and without AKI codes was 104 (57 to 158) μmol/L and 16 (−3 to 41) μmol/L, respectively (Mann-Whitney test, p < 0.0001).

Limitations

The low sensitivity of the AKI code may be due to an alternative diagnosis of acute rejection being assigned in certain cases. The cause of AKI could not be determined.

Conclusions

Similar to the general population, the ICD-10 N17x code misses many kidney transplant patients with AKI during their hospitalization. This makes the code unusable for studying the incidence and consequences of AKI in hospitalized kidney transplant patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s40697-016-0108-7) contains supplementary material, which is available to authorized users.

Incidence, etiology, and significance of acute kidney injury in the early post-kidney transplant period

Little is known about the incidence, causes, and significance of acute kidney injury (AKI) in the early transplant period. This study used a definition as >26 μmol/L increase in creatinine within 48 h or >50% increase over a period >48 h. In 326 adult consecutive recipients of a solitary kidney transplant from 2006 to 2014 followed at this center, 21% developed AKI within the first six months. Most etiologies were CNI toxicity (33%) or unknown (26%), whereas acute rejection accounted for 17% and urinary tract obstruction for 10%. Those with AKI had a significantly lower glomerular filtration rate (GFR) at one-yr post-transplant (adjusted beta coefficient -5.5 mL/min/1.73 m(2) , 95% CI: -10.4, -0.7, p = 0.025) in a multivariable linear regression model. However, the AKI definition missed 6 of 19 episodes of acute rejection and 4 of 10 episodes of urinary tract obstruction. When acute rejection (including those that did not satisfy AKI criteria) was included in the model, other causes of AKI were not significantly associated with GFR at year 1. Although AKI, using current criteria, is likely to be a significant predictor of later outcomes, important causes are missed and the criteria are not sensitive for clinical decision-making.

From the nephrologist's point of view: diversity of causes and clinical features of acute kidney injury

Acute kidney injury (AKI) is a clinical syndrome with multiple entities. Although AKI implies renal damage, functional impairment or both, diagnosis is solely based on the functional parameters of serum creatinine and urine output. The latest definition was provided by the Kidney Disease Improving Global Outcomes (KDIGO) working group in 2012. Independent of the underlying disease, and even in the case of full recovery, AKI is associated with an increased morbidity and mortality. Awareness of the patient's individual risk profile and the diversity of causes and clinical features of AKI is pivotal for optimization of prophylaxes, diagnosis and therapy of each form of AKI. A differentiated and individualized approach is required to improve patient mortality, morbidity, long-term kidney function and eventually the quality of life. In this review, we provide an overview of the different clinical settings in which specific forms of AKI may occur and point out possible diagnostic as well as therapeutic approaches. Secifically AKI is discussed in the context of non-kidney organ failure, organ transplantation, sepsis, malignancy and autoimmune disease.

Comparison of renal function detriments after local tumor ablation or partial nephrectomy for renal cell carcinoma

PURPOSE

Local tumor ablation (LTA) and partial nephrectomy (PN) represent treatment alternatives for patients diagnosed with small renal mass and both may result in renal function detriments. The aim of the study was to compare renal function detriments after LTA or PN.

METHODS

A Surveillance epidemiology and End Results-Medicare-linked retrospective cohort of 2850 T1 kidney cancer patients who underwent LTA or PN was abstracted. Short-term outcomes consisted of 30-day acute kidney injury (AKI) and 30-day dialysis rates. Long-term outcomes consisted of episodes of AKI, mild and moderate-severe chronic kidney disease (CKD), end-stage renal disease, hemodialysis and anemia in CKD. Analyses consisted of propensity score matching, logistic and Cox regression.

RESULTS

After propensity score matching, 1122 patients remained. The 30-day incidence of AKI was 4.6 % after LTA and 9.4 % after PN. In multivariable analyses (MVAs), LTA was associated with a lower AKI rate (OR 0.42; p = 0.001). The 30-day incidence of any dialysis was <2 % after either LTA or PN. In MVA, LTA was not associated with a lower rate of any dialysis (OR 0.43; p = 0.2). At long-term assessment, both the unadjusted and adjusted rates of all six examined end points were not different between LTA and PN (all p > 0.5).

CONCLUSIONS

LTA offers short-term protective effect from AKI. The short-term rates of any dialysis treatment are similar after either LTA or PN. At long-term assessment, LTA and PN renal function detriment rates are not different. Concern for long-term functional outcomes should not be a barrier for PN.

Neutrophil gelatinase-associated lipocalin in kidney transplantation: A review

Neutrophil gelatinase-associated lipocalin (NGAL) is a protein expressed by kidney tubular cells in response to ischemia, but may also be an early indicator of immunological rejection, calcineurin inhibitor toxicity, obstructive nephropathy, subclinical tubulitis or infection. Although there is currently no evidence to support the routine serial measurement of blood or urinary NGAL to detect subclinical acute tubular injury, NGAL has the potential to provide useful information to those that care for kidney transplant recipients (KTRs). First, high urinary or serum NGAL concentrations shortly after transplantation are a predictor of delayed graft function and are associated with reduced graft function at one year. Secondly, among KTRs with previously stable graft function who then suffer acute graft dysfunction, a high urinary NGAL predicts graft loss at one year. If further refined, diagnostic tests based on NGAL levels may provide future useful clinical tools.