Researchers reported a “very high incidence” of acute kidney injury (AKI), severe AKI requiring dialysis, and risk of death associated with AKI in a diverse cohort of patients hospitalized with coronavirus disease 2019 (COVID-19) in New York City, according to a study published in the Journal of the American Society of Nephrology.
“Small studies from China, Europe, and the US thus far have reported a wide range of the incidence of AKI, ranging between 1% and 42%,” said the authors, led by Lili Chan, MD, Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY. In this latest study, they said “AKI occurred in nearly half of patients, and nearly a quarter of those patients required acute dialysis.” Further, AKI was also independently associated with higher mortality, while only 30% of COVID-19 patients with AKI survived with recovery of kidney function by the time of discharge.
As part of the retrospective observational study, investigators reviewed data from electronic health records of patients aged at least 18 years old with laboratory-confirmed COVID-19 admitted to the Mount Sinai Health System (MSHS) from February 27 to May 30, 2020. The authors noted that the MSHS serves a large racially and ethnically diverse patient population. Patients with known end-stage kidney disease (ESKD) prior to admission and those who were hospitalized for less than 48 hours were excluded from the analysis.
A total of 3993 COVID-19–positive patients were hospitalised at one of five MSHS hospitals in New York City. The authors said patients who developed incident AKI were older and were more likely to have hypertension, congestive heart failure, diabetes mellitus, and chronic kidney disease (CKD). They also had higher white blood cell counts, lower lymphocyte percentages, and higher creatinine values.
AKI occurred in 1835 patients (46%), and 347 (19%) of those with AKI required dialysis. The median time from hospital admission until AKI diagnoses was 1 day (IQR, 1–4), and the median time from AKI diagnosis to dialysis need was 3 days (IQR, 1–6). The proportions with stages 1, 2, or 3 AKI were 39%, 19%, and 42%, respectively. Median peak serum creatinine was 2.2 mg/dL (IQR, 1.5–3.6) in those who did not receive dialysis and was 8.2 mg/dL (IQR, 6.1–11) in those who did.
A total of 976 (24%) patients were admitted to intensive care, and 745 (76%) of these experienced AKI. For those admitted to the ICU, 28% were classified as having stage 1 AKI, 17% as stage 2, and 56% as stage 3, while 32% required acute renal replacement therapy. Independent predictors of severe AKI were CKD (aOR, 2.8; 95% confidence interval [95% CI], 2.1 to 3.7), admission potassium (aOR, 1.7; 95% CI, 1.6 to 2.0) and men (aOR, 1.46; 95% CI, 1.2 to 1.8).
Urine studies were available for 656 (16%) patients, of whom 435 (66%) patients had AKI. Among these AKI patients with urine studies, 84% had proteinuria, 81% had hematuria, and 60% had leukocyturia.
In-hospital mortality was 50% among patients with AKI versus 8% among those without AKI (aOR, 9.2; 95% confidence interval, 7.5 to 11.3, P<0.001). Results showed that in-hospital death rates of patients with AKI in the ICU (42%), and non-ICU setting (62%) were markedly higher than those without AKI (ICU, 7% and non-ICU, 13%).
Of the 1835 patients with AKI, 832 were discharged with a median serum creatinine of 1.1 mg/dL (IQR, 0.8–1.6 mg/dL). Among discharged patients, 541 (65%) had recovered from AKI when they left hospital, while 291 (35%) survivors had acute kidney disease (AKD). The authors said their findings show that overall, only 30% (541 of 1835) of the AKI patients in their study survived and recovered renal function.
Meanwhile, 212 of 1835 (12%) patients with AKI had follow-up creatinine data at a median of 21 days (IQR, 8–38) post-discharge. Among these 212 patients, 77 had AKD on discharge, and 28 of these 77 (36%) had recovered from AKD on follow-up. Meanwhile, 135 of 212 (64%) patients were recovered from AKI at discharge, although 18 (14%) of these 135 had AKD on follow-up.
“The incidence of AKI in this study is higher than what has been reported in China and Italy and similar to the incidence in another NYC healthcare system,” the authors said, noting that there are several key differences in the MSHS cohort, including higher proportions of patients with comorbidities of hypertension, diabetes, and CKD. “In our analysis, there was no association between hypertension and diabetes with severe AKI, but CKD was independently associated with severe AKI.”
They also noted that of the 656 COVID-19 patients in their cohort who had urine studies sent, nearly all (97%) were found to have urinary abnormalities, although such abnormalities were more frequent among patients with an AKI diagnosis. “These findings are in contrast to studies in critically ill patients and patients undergoing cardiac surgery that demonstrated that only 33%–48% of patients had proteinuria and that 65% had hematuria. Given the high incidence of AKI and lack of full recovery at and after discharge, identification of potential mechanisms of COVID-19–related AKI would allow for potential interventions to reduce this devastating complication,” the authors said.
“This study is the first study in the US to report the persistence of kidney dysfunction in survivors of COVID-19–associated AKI…The low recovery rate is expected given the overall severity of AKI, as well as the knowledge that many patients with COVID-19 have extensive acute tubular injury on tissue examination, potential microthrombi, and a high prevalence of proteinuria,” the authors said. However, they pointed to a “marked contrast to other forms of AKI where over 80% of patients recover their renal function by 10 days…This will require long-term follow-up and further investigation.”