Pathology of COVID-19-associated acute kidney injury.

Acute kidney injury (AKI) is common among hospitalized patients with coronavirus disease 2019 (COVID-19), with the occurrence of AKI ranging from 0.5% to 80%. An improved knowledge of the pathology of AKI in COVID-19 is crucial to mitigate and manage AKI and to improve the survival of patients who develop AKI during COVID-19. In this review, we summarize the published cases and case series of various kidney pathologies seen with COVID-19. Both live kidney biopsies and autopsy series suggest acute tubular injury as the most commonly encountered pathology. Collapsing glomerulopathy and thrombotic microangiopathy are other encountered pathologies noted in both live and autopsy tissues. Other rare findings such as anti-neutrophil cytoplasmic antibody vasculitis, anti-glomerular basement membrane disease and podocytopathies have been reported. Although direct viral infection of the kidney is possible, it is certainly not a common or even widespread finding reported at the time of this writing (November 2020).

Outcomes Among Patients Hospitalized With COVID-19 and Acute Kidney Injury.

RATIONALE & OBJECTIVE: Outcomes of patients hospitalized with coronavirus disease 2019 (COVID-19) and acute kidney injury (AKI) are not well understood. The goal of this study was to investigate the survival and kidney outcomes of these patients. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: Patients (aged≥18 years) hospitalized with COVID-19 at 13 hospitals in metropolitan New York between March 1, 2020, and April 27, 2020, followed up until hospital discharge. EXPOSURE: AKI. OUTCOMES: Primary outcome: in-hospital death. SECONDARY OUTCOMES: requiring dialysis at discharge, recovery of kidney function. ANALYTICAL APPROACH: Univariable and multivariable time-to-event analysis and logistic regression. RESULTS: Among 9,657 patients admitted with COVID-19, the AKI incidence rate was 38.4/1,000 patient-days. Incidence rates of in-hospital death among patients without AKI, with AKI not requiring dialysis (AKI stages 1-3), and with AKI receiving dialysis (AKI 3D) were 10.8, 31.1, and 37.5/1,000 patient-days, respectively. Taking those without AKI as the reference group, we observed greater risks for in-hospital death for patients with AKI 1-3 and AKI 3D (HRs of 5.6 [95% CI, 5.0-6.3] and 11.3 [95% CI, 9.6-13.1], respectively). After adjusting for demographics, comorbid conditions, and illness severity, the risk for death remained higher among those with AKI 1-3 (adjusted HR, 3.4 [95% CI, 3.0-3.9]) and AKI 3D (adjusted HR, 6.4 [95% CI, 5.5-7.6]) compared with those without AKI. Among patients with AKI 1-3 who survived, 74.1% achieved kidney recovery by the time of discharge. Among those with AKI 3D who survived, 30.6% remained on dialysis at discharge, and prehospitalization chronic kidney disease was the only independent risk factor associated with needing dialysis at discharge (adjusted OR, 9.3 [95% CI, 2.3-37.8]). LIMITATIONS: Observational retrospective study, limited to the NY metropolitan area during the peak of the COVID-19 pandemic. CONCLUSIONS: AKI in hospitalized patients with COVID-19 was associated with significant risk for death.

Outcomes of patients with end-stage kidney disease hospitalized with COVID-19.

Given the high risk of infection-related mortality, patients with end-stage kidney disease (ESKD) may be at increased risk with COVID-19. To assess this, we compared outcomes of patients with and without ESKD, hospitalized with COVID-19. This was a retrospective study of patients admitted with COVID-19 from 13 New York hospitals from March 1, 2020, to April 27, 2020, and followed through May 27, 2020. We measured primary outcome (in-hospital death), and secondary outcomes (mechanical ventilation and length of stay). Of 10,482 patients with COVID-19, 419 had ESKD. Patients with ESKD were older, had a greater percentage self-identified as Black, and more comorbid conditions. Patients with ESKD had a higher rate of in-hospital death than those without (31.7% vs 25.4%, odds ratio 1.38, 95% confidence interval 1.12 - 1.70). This increase rate remained after adjusting for demographic and comorbid conditions (adjusted odds ratio 1.37, 1.09 - 1.73). The odds of length of stay of seven or more days was higher in the group with compared to the group without ESKD in both the crude and adjusted analysis (1.62, 1.27 - 2.06; vs 1.57, 1.22 - 2.02, respectively). There was no difference in the odds of mechanical ventilation between the groups. Independent risk factors for in-hospital death for patients with ESKD were increased age, being on a ventilator, lymphopenia, blood urea nitrogen and serum ferritin. Black race was associated with a lower risk of death. Thus, among patients hospitalized with COVID-19, those with ESKD had a higher rate of in-hospital death compared to those without ESKD.

COVID-19-Associated Kidney Injury: A Case Series of Kidney Biopsy Findings.

BACKGROUND: Reports show that AKI is a common complication of severe coronavirus disease 2019 (COVID-19) in hospitalized patients. Studies have also observed proteinuria and microscopic hematuria in such patients. Although a recent autopsy series of patients who died with severe COVID-19 in China found acute tubular necrosis in the kidney, a few patient reports have also described collapsing glomerulopathy in COVID-19. METHODS: We evaluated biopsied kidney samples from ten patients at our institution who had COVID-19 and clinical features of AKI, including proteinuria with or without hematuria. We documented clinical features, pathologic findings, and outcomes. RESULTS: Our analysis included ten patients who underwent kidney biopsy (mean age: 65 years); five patients were black, three were Hispanic, and two were white. All patients had proteinuria. Eight patients had severe AKI, necessitating RRT. All biopsy samples showed varying degrees of acute tubular necrosis, and one patient had associated widespread myoglobin casts. In addition, two patients had findings of thrombotic microangiopathy, one had pauci-immune crescentic GN, and another had global as well as segmental glomerulosclerosis with features of healed collapsing glomerulopathy. Interestingly, although the patients had confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by RT-PCR, immunohistochemical staining of kidney biopsy samples for SARS-CoV-2 was negative in all ten patients. Also, ultrastructural examination by electron microscopy showed no evidence of viral particles in the biopsy samples. CONCLUSIONS: The most common finding in our kidney biopsy samples from ten hospitalized patients with AKI and COVID-19 was acute tubular necrosis. There was no evidence of SARS-CoV-2 in the biopsied kidney tissue.