AKI Treated with Renal Replacement Therapy in Critically Ill Patients with COVID-19

BACKGROUND

AKI is a common sequela of coronavirus disease 2019 (COVID-19). However, few studies have focused on AKI treated with RRT (AKI-RRT).

METHODS

We conducted a multicenter cohort study of 3099 critically ill adults with COVID-19 admitted to intensive care units (ICUs) at 67 hospitals across the United States. We used multivariable logistic regression to identify patient-and hospital-level risk factors for AKI-RRT and to examine risk factors for 28-day mortality among such patients.

RESULTS

A total of 637 of 3099 patients (20.6%) developed AKI-RRT within 14 days of ICU admission, 350 of whom (54.9%) died within 28 days of ICU admission. Patient-level risk factors for AKI-RRT included CKD, men, non-White race, hypertension, diabetes mellitus, higher body mass index, higher d-dimer, and greater severity of hypoxemia on ICU admission. Predictors of 28-day mortality in patients with AKI-RRT were older age, severe oliguria, and admission to a hospital with fewer ICU beds or one with greater regional density of COVID-19. At the end of a median follow-up of 17 days (range, 1-123 days), 403 of the 637 patients (63.3%) with AKI-RRT had died, 216 (33.9%) were discharged, and 18 (2.8%) remained hospitalized. Of the 216 patients discharged, 73 (33.8%) remained RRT dependent at discharge, and 39 (18.1%) remained RRT dependent 60 days after ICU admission.

CONCLUSIONS

AKI-RRT is common among critically ill patients with COVID-19 and is associated with a hospital mortality rate of >60%. Among those who survive to discharge, one in three still depends on RRT at discharge, and one in six remains RRT dependent 60 days after ICU admission.

A multi-center study on safety and efficacy of immune checkpoint inhibitors in cancer patients with kidney transplant

Immune checkpoint inhibitors (ICIs) are widely used for various malignancies. However, their safety and efficacy in patients with a kidney transplant have not been defined. To delineate this, we conducted a multicenter retrospective study of 69 patients with a kidney transplant receiving ICIs between January 2010 and May 2020. For safety, we assessed the incidence, timing, and risk factors of acute graft rejection. For efficacy, objective response rate and overall survival were assessed in cutaneous squamous cell carcinoma and melanoma, the most common cancers in our cohort, and compared with stage-matched 23 patients with squamous cell carcinoma and 14 with melanoma with a kidney transplant not receiving ICIs. Following ICI treatment, 29 out of 69 (42%) patients developed acute rejection, 19 of whom lost their allograft, compared with an acute rejection rate of 5.4% in the non-ICI cohort. Median time from ICI initiation to rejection was 24 days. Factors associated with a lower risk of rejection were mTOR inhibitor use (odds ratio 0.26; 95% confidence interval, 0.09-0.72) and triple-agent immunosuppression (0.67, 0.48-0.92). The objective response ratio was 36.4% and 40% in the squamous cell carcinoma and melanoma subgroups, respectively. In the squamous cell carcinoma subgroup, overall survival was significantly longer in patients treated with ICIs (median overall survival 19.8 months vs. 10.6 months), whereas in the melanoma subgroup, overall survival did not differ between groups. Thus, ICIs were associated with a high risk of rejection in patients with kidney transplants but may lead to improved cancer outcomes. Prospective studies are needed to determine optimal immunosuppression strategies to improve patient outcomes.

Outcomes of critically ill solid organ transplant patients with COVID-19 in the United States

National data on patient characteristics, treatment, and outcomes of critically ill coronavirus disease 2019 (COVID-19) solid organ transplant (SOT) patients are limited. We analyzed data from a multicenter cohort study of adults with laboratory-confirmed COVID-19 admitted to intensive care units (ICUs) at 68 hospitals across the United States from March 4 to May 8, 2020. From 4153 patients, we created a propensity score matched cohort of 386 patients, including 98 SOT patients and 288 non-SOT patients. We used a binomial generalized linear model (log-binomial model) to examine the association of SOT status with death and other clinical outcomes. Among the 386 patients, the median age was 60 years, 72% were male, and 41% were black. Death within 28 days of ICU admission was similar in SOT and non-SOT patients (40% and 43%, respectively; relative risk [RR] 0.92; 95% confidence interval [CI]: 0.70-1.22). Other outcomes and requirement for organ support including receipt of mechanical ventilation, development of acute respiratory distress syndrome, and receipt of vasopressors were also similar between groups. There was a trend toward higher risk of acute kidney injury requiring renal replacement therapy in SOT vs. non-SOT patients (37% vs. 27%; RR [95% CI]: 1.34 [0.97-1.85]). Death and organ support requirement were similar between SOT and non-SOT critically ill patients with COVID-19.

Factors Associated With Death in Critically Ill Patients With Coronavirus Disease 2019 in the US

Importance

The US is currently an epicenter of the coronavirus disease 2019 (COVID-19) pandemic, yet few national data are available on patient characteristics, treatment, and outcomes of critical illness from COVID-19.

Objectives

To assess factors associated with death and to examine interhospital variation in treatment and outcomes for patients with COVID-19.

Design, Setting, and Participants

This multicenter cohort study assessed 2215 adults with laboratory-confirmed COVID-19 who were admitted to intensive care units (ICUs) at 65 hospitals across the US from March 4 to April 4, 2020.

Exposures

Patient-level data, including demographics, comorbidities, and organ dysfunction, and hospital characteristics, including number of ICU beds.

Main Outcomes and Measures

The primary outcome was 28-day in-hospital mortality. Multilevel logistic regression was used to evaluate factors associated with death and to examine interhospital variation in treatment and outcomes.

Results

A total of 2215 patients (mean [SD] age, 60.5 [14.5] years; 1436 [64.8%] male; 1738 [78.5%] with at least 1 chronic comorbidity) were included in the study. At 28 days after ICU admission, 784 patients (35.4%) had died, 824 (37.2%) were discharged, and 607 (27.4%) remained hospitalized. At the end of study follow-up (median, 16 days; interquartile range, 8-28 days), 875 patients (39.5%) had died, 1203 (54.3%) were discharged, and 137 (6.2%) remained hospitalized. Factors independently associated with death included older age (≥80 vs <40 years of age: odds ratio [OR], 11.15; 95% CI, 6.19-20.06), male sex (OR, 1.50; 95% CI, 1.19-1.90), higher body mass index (≥40 vs <25: OR, 1.51; 95% CI, 1.01-2.25), coronary artery disease (OR, 1.47; 95% CI, 1.07-2.02), active cancer (OR, 2.15; 95% CI, 1.35-3.43), and the presence of hypoxemia (Pao2:Fio2<100 vs ≥300 mm Hg: OR, 2.94; 95% CI, 2.11-4.08), liver dysfunction (liver Sequential Organ Failure Assessment score of 2-4 vs 0: OR, 2.61; 95% CI, 1.30-5.25), and kidney dysfunction (renal Sequential Organ Failure Assessment score of 4 vs 0: OR, 2.43; 95% CI, 1.46-4.05) at ICU admission. Patients admitted to hospitals with fewer ICU beds had a higher risk of death (<50 vs ≥100 ICU beds: OR, 3.28; 95% CI, 2.16-4.99). Hospitals varied considerably in the risk-adjusted proportion of patients who died (range, 6.6%-80.8%) and in the percentage of patients who received hydroxychloroquine, tocilizumab, and other treatments and supportive therapies.

Conclusions and Relevance

This study identified demographic, clinical, and hospital-level risk factors that may be associated with death in critically ill patients with COVID-19 and can facilitate the identification of medications and supportive therapies to improve outcomes.

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.

In-hospital cardiac arrest in critically ill patients with covid-19: multicenter cohort study

OBJECTIVES

To estimate the incidence, risk factors, and outcomes associated with in-hospital cardiac arrest and cardiopulmonary resuscitation in critically ill adults with coronavirus disease 2019 (covid-19).

DESIGN

Multicenter cohort study.

SETTING

Intensive care units at 68 geographically diverse hospitals across the United States.

PARTICIPANTS

Critically ill adults (age ≥18 years) with laboratory confirmed covid-19.

MAIN OUTCOME MEASURES

In-hospital cardiac arrest within 14 days of admission to an intensive care unit and in-hospital mortality.

RESULTS

Among 5019 critically ill patients with covid-19, 14.0% (701/5019) had in-hospital cardiac arrest, 57.1% (400/701) of whom received cardiopulmonary resuscitation. Patients who had in-hospital cardiac arrest were older (mean age 63 (standard deviation 14) v 60 (15) years), had more comorbidities, and were more likely to be admitted to a hospital with a smaller number of intensive care unit beds compared with those who did not have in-hospital cardiac arrest. Patients who received cardiopulmonary resuscitation were younger than those who did not (mean age 61 (standard deviation 14) v 67 (14) years). The most common rhythms at the time of cardiopulmonary resuscitation were pulseless electrical activity (49.8%, 199/400) and asystole (23.8%, 95/400). 48 of the 400 patients (12.0%) who received cardiopulmonary resuscitation survived to hospital discharge, and only 7.0% (28/400) survived to hospital discharge with normal or mildly impaired neurological status. Survival to hospital discharge differed by age, with 21.2% (11/52) of patients younger than 45 years surviving compared with 2.9% (1/34) of those aged 80 or older.

CONCLUSIONS

Cardiac arrest is common in critically ill patients with covid-19 and is associated with poor survival, particularly among older patients.

The Macrophage Migration Inhibitory Factor (MIF) Promoter Polymorphisms (rs3063368, rs755622) Predict Acute Kidney Injury and Death after Cardiac Surgery

Background: Macrophage Migration Inhibitory Factor (MIF) is highly elevated after cardiac surgery and impacts the postoperative inflammation. The aim of this study was to analyze whether the polymorphisms CATT_5–7 (rs5844572/rs3063368,“-794”) and G>C single-nucleotide polymorphism (rs755622,-173) in the MIF gene promoter are related to postoperative outcome. Methods: In 1116 patients undergoing cardiac surgery, the MIF gene polymorphisms were analyzed and serum MIF was measured by ELISA in 100 patients. Results: Patients with at least one extended repeat allele (CATT₇) had a significantly higher risk of acute kidney injury (AKI) compared to others (23% vs. 13%; OR 2.01 (1.40–2.88), p = 0.0001). Carriers of CATT₇ were also at higher risk of death (1.8% vs. 0.4%; OR 5.12 (0.99–33.14), p = 0.026). The GC genotype was associated with AKI (20% vs. GG/CC:13%, OR 1.71 (1.20–2.43), p = 0.003). Multivariate analyses identified CATT₇ predictive for AKI (OR 2.13 (1.46–3.09), p < 0.001) and death (OR 5.58 (1.29–24.04), p = 0.021). CATT₇ was associated with higher serum MIF before surgery (79.2 vs. 50.4 ng/mL, p = 0.008). Conclusion: The CATT₇ allele associates with a higher risk of AKI and death after cardiac surgery, which might be related to chronically elevated serum MIF. Polymorphisms in the MIF gene may constitute a predisposition for postoperative complications and the assessment may improve risk stratification and therapeutic guidance.

Post-sepsis immunosuppression depends on NKT cell regulation of mTOR/IFN-γ in NK cells

As treatment of the early, inflammatory phase of sepsis improves, post-sepsis immunosuppression and secondary infection have increased in importance. How early inflammation drives immunosuppression remains unclear. Although IFN-γ typically helps microbial clearance, we found that increased plasma IFN-γ in early clinical sepsis was associated with the later development of secondary Candida infection. Consistent with this observation, we found that exogenous IFN-γ suppressed macrophage phagocytosis of zymosan in vivo, and antibody blockade of IFN-γ after endotoxemia improved survival of secondary candidemia. Transcriptomic analysis of innate lymphocytes during endotoxemia suggested that NKT cells drove IFN-γ production by NK cells via mTORC1. Activation of invariant NKT (iNKT) cells with glycolipid antigen drove immunosuppression. Deletion of iNKT cells in Cd1d-/- mice or inhibition of mTOR by rapamycin reduced immunosuppression and susceptibility to secondary Candida infection. Thus, although rapamycin is typically an immunosuppressive medication, in the context of sepsis, rapamycin has the opposite effect. These results implicated an NKT cell/mTOR/IFN-γ axis in immunosuppression following endotoxemia or sepsis. In summary, in vivo iNKT cells activated mTORC1 in NK cells to produce IFN-γ, which worsened macrophage phagocytosis, clearance of secondary Candida infection, and mortality.

Acute kidney injury after cytoreductive surgery and hyperthermic intraoperative cisplatin chemotherapy for malignant pleural mesothelioma

OBJECTIVES

Cytoreductive surgery with hyperthermic intraoperative chemotherapy with cisplatin has been used successfully to treat malignant pleural mesothelioma, a highly aggressive malignancy that is rapidly fatal in most cases. We hypothesized that the combination of ischemic injury with nephrotoxic injury from cisplatin would result in high rates of acute kidney injury.

METHODS

We conducted an observational study in 503 patients to study the risks and outcomes of acute kidney injury after surgical resection of malignant pleural mesothelioma. Eligible subjects underwent extrapleural pneumonectomy or pleurectomy/decortication with or without hyperthermic intraoperative chemotherapy. Acute kidney injury was defined as an increase in creatinine of 26.5 μmol/L or greater within 48 hours of surgery or a 50% or greater increase over 7 days.

RESULTS

Acute kidney injury developed in 243 patients (48.3%). Severe acute kidney injury requiring renal replacement therapy developed in 16 patients (3.2%). Major significant predictors for acute kidney injury included male sex (odds ratio, 2.98; P < .001), intraoperative cisplatin administration (odds ratio, 3.12; P < .001), previous cisplatin exposure (odds ratio, 1.96; P = .02), hypertension (odds ratio, 1.57; P = .02), and longer surgical time (odds ratio, 1.15 per hour; P = .02). Compared with patients without acute kidney injury, those with severe acute kidney injury had longer length of stay (26 vs 13 days) and a 2.71-fold increased risk of death in multivariable-adjusted models.

CONCLUSIONS

Acute kidney injury is common after cytoreductive surgery with hyperthermic intraoperative chemotherapy with cisplatin and is associated with poor long-term outcomes. Strategies to prevent postoperative acute kidney injury are needed to improve multimodal treatment of malignant pleural mesothelioma.

Glycerol-3-phosphate is an FGF23 regulator derived from the injured kidney

Fibroblast growth factor 23 (FGF23) is a bone-derived hormone that controls blood phosphate levels by increasing renal phosphate excretion and reducing 1,25-dihydroxyvitamin D3 [1,25(OH)2D] production. Disorders of FGF23 homeostasis are associated with significant morbidity and mortality, but a fundamental understanding of what regulates FGF23 production is lacking. Because the kidney is the major end organ of FGF23 action, we hypothesized that it releases a factor that regulates FGF23 synthesis. Using aptamer-based proteomics and liquid chromatography-mass spectrometry-based (LC-MS-based) metabolomics, we profiled more than 1600 molecules in renal venous plasma obtained from human subjects. Renal vein glycerol-3-phosphate (G-3-P) had the strongest correlation with circulating FGF23. In mice, exogenous G-3-P stimulated bone and bone marrow FGF23 production through local G-3-P acyltransferase-mediated (GPAT-mediated) lysophosphatidic acid (LPA) synthesis. Further, the stimulatory effect of G-3-P and LPA on FGF23 required LPA receptor 1 (LPAR1). Acute kidney injury (AKI), which increases FGF23 levels, rapidly increased circulating G-3-P in humans and mice, and the effect of AKI on FGF23 was abrogated by GPAT inhibition or Lpar1 deletion. Together, our findings establish a role for kidney-derived G-3-P in mineral metabolism and outline potential targets to modulate FGF23 production during kidney injury.

Immune Checkpoint Inhibitor Nephrotoxicity: Update 2020

Immune checkpoint inhibitors (ICPIs) have transformed the landscape of oncology, but are associated with a variety of autoimmune adverse events, including AKI. ICPI-associated AKI (ICPI-AKI) is emerging as an increasingly frequent cause of AKI in patients with cancer, and poses unique diagnostic and management challenges to clinicians who care for these patients. In this review, we describe the incidence and risk factors for ICPI-AKI, including proton pump inhibitor use, CKD, and combination immunotherapy. We discuss the limitations of the various definitions used for ICPI-AKI in prior studies, and propose a novel classification system (definite, probable, and possible ICPI-AKI) that recognizes the diagnostic uncertainty inherent in many cases. We discuss the key clinicopathologic features and treatment strategies for ICPI-AKI, including the role of kidney biopsy versus empirical treatment with steroids. We also explore the under-studied area of ICPI use in the setting of solid organ transplantation, where nephrologists and oncologists must balance the risk of rejection versus treating the underlying malignancy. Finally, we summarize existing data on the role of ICPI rechallenge after an episode of ICPI-AKI.

Clinical Features and Outcomes of Immune Checkpoint Inhibitor-Associated AKI: A Multicenter Study

BACKGROUND

Despite increasing recognition of the importance of immune checkpoint inhibitor-associated AKI, data on this complication of immunotherapy are sparse.

METHODS

We conducted a multicenter study of 138 patients with immune checkpoint inhibitor-associated AKI, defined as a ≥2-fold increase in serum creatinine or new dialysis requirement directly attributed to an immune checkpoint inhibitor. We also collected data on 276 control patients who received these drugs but did not develop AKI.

RESULTS

Lower baseline eGFR, proton pump inhibitor use, and combination immune checkpoint inhibitor therapy were each independently associated with an increased risk of immune checkpoint inhibitor-associated AKI. Median (interquartile range) time from immune checkpoint inhibitor initiation to AKI was 14 (6-37) weeks. Most patients had subnephrotic proteinuria, and approximately half had pyuria. Extrarenal immune-related adverse events occurred in 43% of patients; 69% were concurrently receiving a potential tubulointerstitial nephritis-causing medication. Tubulointerstitial nephritis was the dominant lesion in 93% of the 60 patients biopsied. Most patients (86%) were treated with steroids. Complete, partial, or no kidney recovery occurred in 40%, 45%, and 15% of patients, respectively. Concomitant extrarenal immune-related adverse events were associated with worse renal prognosis, whereas concomitant tubulointerstitial nephritis-causing medications and treatment with steroids were each associated with improved renal prognosis. Failure to achieve kidney recovery after immune checkpoint inhibitor-associated AKI was independently associated with higher mortality. Immune checkpoint inhibitor rechallenge occurred in 22% of patients, of whom 23% developed recurrent associated AKI.

CONCLUSIONS

This multicenter study identifies insights into the risk factors, clinical features, histopathologic findings, and renal and overall outcomes in patients with immune checkpoint inhibitor-associated AKI.

Soluble Urokinase Receptor and Acute Kidney Injury

BACKGROUND

Acute kidney injury is common, with a major effect on morbidity and health care utilization. Soluble urokinase plasminogen activator receptor (suPAR) is a signaling glycoprotein thought to be involved in the pathogenesis of kidney disease. We investigated whether a high level of suPAR predisposed patients to acute kidney injury in multiple clinical contexts, and we used experimental models to identify mechanisms by which suPAR acts and to assess it as a therapeutic target.

METHODS

We measured plasma levels of suPAR preprocedurally in patients who underwent coronary angiography and patients who underwent cardiac surgery and at the time of admission to the intensive care unit in critically ill patients. We assessed the risk of acute kidney injury at 7 days as the primary outcome and acute kidney injury or death at 90 days as a secondary outcome, according to quartile of suPAR level. In experimental studies, we used a monoclonal antibody to urokinase plasminogen activator receptor (uPAR) as a therapeutic strategy to attenuate acute kidney injury in transgenic mice receiving contrast material. We also assessed cellular bioenergetics and generation of reactive oxygen species in human kidney proximal tubular (HK-2) cells that were exposed to recombinant suPAR.

RESULTS

The suPAR level was assessed in 3827 patients who were undergoing coronary angiography, 250 who were undergoing cardiac surgery, and 692 who were critically ill. Acute kidney injury developed in 318 patients (8%) who had undergone coronary angiography. The highest suPAR quartile (vs. the lowest) had an adjusted odds ratio of 2.66 (95% confidence interval [CI], 1.77 to 3.99) for acute kidney injury and 2.29 (95% CI, 1.71 to 3.06) for acute kidney injury or death at 90 days. Findings were similar in the surgical and critically ill cohorts. The suPAR-overexpressing mice that were given contrast material had greater functional and histologic evidence of acute kidney injury than wild-type mice. The suPAR-treated HK-2 cells showed heightened energetic demand and mitochondrial superoxide generation. Pretreatment with a uPAR monoclonal antibody attenuated kidney injury in suPAR-overexpressing mice and normalized bioenergetic changes in HK-2 cells.

CONCLUSIONS

High suPAR levels were associated with acute kidney injury in various clinical and experimental contexts. (Funded by the National Institutes of Health and others.).

Acute Kidney Injury and Electrolyte Abnormalities After Chimeric Antigen Receptor T-Cell (CAR-T) Therapy for Diffuse Large B-Cell Lymphoma

RATIONALE & OBJECTIVE

Cytokine release syndrome is a well-known complication of chimeric antigen receptor T-cell (CAR-T) therapy and can lead to multiorgan dysfunction. However, the nephrotoxicity of CAR-T therapy is unknown. We aimed to characterize the occurrence, cause, and outcomes of acute kidney injury (AKI), along with the occurrence of electrolyte abnormalities, among adults with diffuse large B-cell lymphoma receiving CAR-T therapy.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

We reviewed the course of 78 adults receiving CAR-T therapy with axicabtagene ciloleucel or tisagenlecleucel at 2 major cancer centers between October 2017 and February 2019. Baseline demographics, comorbid conditions, medications, and laboratory values were obtained from electronic health records. AKI was defined using KDIGO (Kidney Disease: Improving Global Outcomes) criteria. The cause, clinical course, and outcome of AKI events and electrolyte abnormalities in the first 30 days after CAR-T infusion were characterized using data contained in electronic health records.

RESULTS

Among 78 patients receiving CAR-T therapy, cytokine release syndrome occurred in 85%, of whom 62% were treated with tocilizumab. AKI occurred in 15 patients (19%): 8 had decreased kidney perfusion, 6 developed acute tubular necrosis, and 1 patient had urinary obstruction related to disease progression. Those with acute tubular necrosis and obstruction had the longest lengths of stay and highest 60-day mortality. Electrolyte abnormalities were common; hypophosphatemia, hypokalemia, and hyponatremia occurred in 75%, 56%, and 51% of patients, respectively.

LIMITATIONS

Small sample size; AKI adjudicated by retrospective chart review; lack of biopsy data.

CONCLUSIONS

In this case series of patients with diffuse large B-cell lymphoma receiving CAR-T therapy, AKI and electrolyte abnormalities occurred commonly in the context of cytokine release syndrome.

Secretory Leukocyte Protease Inhibitor (SLPI)-A Novel Predictive Biomarker of Acute Kidney Injury after Cardiac Surgery: A Prospective Observational Study

Acute kidney injury (AKI) is one of the most frequent complications after cardiac surgery and is associated with poor outcomes. Biomarkers of AKI are crucial for the early diagnosis of this condition. Secretory leukocyte protease inhibitor (SLPI) is an alarm anti-protease that has been implicated in the pathogenesis of AKI but has not yet been studied as a diagnostic biomarker of AKI. Using two independent cohorts (development cohort (DC), n = 60; validation cohort (VC), n = 148), we investigated the performance of SLPI as a diagnostic marker of AKI after cardiac surgery. Serum and urinary levels of SLPI were quantified by ELISA. SLPI was significantly elevated in AKI patients compared with non-AKI patients (6 h, DC: 102.1 vs. 64.9 ng/mL, p < 0.001). The area under the receiver operating characteristic curve of serum SLPI 6 h after surgery was 0.87 ((0.76–0.97); DC). The addition of SLPI to standard clinical predictors significantly improved the predictive accuracy of AKI (24 h, VC: odds ratio (OR) = 3.91 (1.44–12.13)). In a subgroup, the increase in serum SLPI was evident before AKI was diagnosed on the basis of serum creatinine or urine output (24 h, VC: OR = 4.89 (1.54–19.92)). In this study, SLPI was identified as a novel candidate biomarker for the early diagnosis of AKI after cardiac surgery.

The Incidence, Causes, and Risk Factors of Acute Kidney Injury in Patients Receiving Immune Checkpoint Inhibitors

BACKGROUND AND OBJECTIVES

Immune checkpoint inhibitor use in oncology is increasing rapidly. We sought to determine the frequency, severity, cause, and predictors of AKI in a real-world population receiving checkpoint inhibitors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We included all patients who received checkpoint inhibitor therapy from May 2011 to December 2016 at Massachusetts General Hospital. Baseline serum creatinine, averaged 6 months before checkpoint inhibitor start date, was compared with all subsequent creatinine values within 12 months of starting therapy. AKI was defined by Kidney Disease: Improving Global Outcomes criteria for fold changes in creatinine from baseline. Sustained AKI events lasted at least 3 days and was our primary outcome. The cause of sustained AKI was determined by chart review. Cumulative incidence and subdistribution hazard models were used to assess the relationship between baseline demographics, comorbidities, and medications, and sustained AKI and potential checkpoint inhibitor-related AKI.

RESULTS

We included 1016 patients in the analysis. Average age was 63 (SD 13) years, 61% were men, and 91% were white. Mean baseline creatinine was 0.9 mg/dl (SD 0.4 mg/dl), and 169 (17%) had CKD (eGFR<60 ml/min per 1.73 m²) at baseline. A total of 169 patients (17%) experienced AKI, defined by an increase in creatinine at least 1.5 times the baseline within 12 months; 82 patients (8%) experienced sustained AKI and 30 patients (3%) had potential checkpoint inhibitor-related AKI. The first episode of sustained AKI occurred, on average, 106 days (SD 85) after checkpoint inhibitor initiation. Sixteen (2%) patients experienced stage 3 sustained AKI and four patients required dialysis. Proton pump inhibitor use at baseline was associated with sustained AKI.

CONCLUSIONS

AKI is common in patients receiving checkpoint inhibitor therapy. The causes of sustained AKI in this population are heterogenous and merit thorough evaluation. The role of PPI and other nephritis-inducing drugs in the development of sustained AKI needs to be better defined.

Iron Chelation as a Potential Therapeutic Strategy for AKI Prevention

AKI remains a major public health concern. Despite years of investigation, no intervention has been demonstrated to reliably prevent AKI in humans. Thus, development of novel therapeutic targets is urgently needed. An important role of iron in the pathophysiology of AKI has been recognized for over three decades. When present in excess and in nonphysiologic labile forms, iron is toxic to the kidneys and multiple other organs, whereas iron chelation is protective across a broad spectrum of insults. In humans, small studies have investigated iron chelation as a novel therapeutic strategy for prevention of AKI and extrarenal acute organ injury, and have demonstrated encouraging initial results. In this review, we examine the existing data on iron chelation for AKI prevention in both animal models and human studies. We discuss practical considerations for future clinical trials of AKI prevention using iron chelators, including selection of the ideal clinical setting, patient population, iron chelating agent, and dosing regimen. Finally, we compare the key differences among the currently available iron chelators, including pharmacokinetics, routes of administration, and adverse effects.

Prevention of Cardiac Surgery-Associated Acute Kidney Injury: A Review of Current Strategies

Acute kidney injury is a common and often severe postoperative complication after cardiac surgery, and is associated with poor short-term and long-term outcomes. Numerous randomized controlled trials have been conducted to investigate various strategies for prevention of cardiac surgery-associated acute kidney injury. Unfortunately, most trials that have been conducted to date have been negative. However, encouraging results have been demonstrated with preoperative administration of corticosteroids, leukocyte filtration, and administration of inhaled nitric oxide intraoperatively, and implementation of a Kidney Disease: Improving Global Outcomes bundle of care approach postoperatively. These findings require validation in large, multicenter trials.

A case of severe hypothyroidism due to lenalidomide

Lenalidomide, an immunomodulatory drug often used to treat multiple myeloma, can cause hypo- or hyperthyroidism. We present a patient being treated with lenalidomide for 2 years who developed severe hypothyroidism that was complicated by rhabdomyolysis and acute kidney injury. Thyroid function tests should be serially monitored in patients taking lenalidomide.