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Study Finds 72% of Critically Ill COVID-19 Patients Developed Acute Kidney Injury

Key findings

  • Prospectively collected data on 206 critically ill COVID-19 patients showed that 148 (72%) developed acute kidney injury (AKI)
  • 70 patients had stage 3 AKI, and 46 of them (66%) required renal replacement therapy (RRT)
  • Male sex was a strong independent predictor of the development of AKI (OR, 4.42), as was the need for RRT (OR, 3.05); hypertension also predicted the need for RRT (OR, 3.15)
  • The hospital mortality rate was 33.1% for patients with AKI and 8.6% for those without (P < .001)
  • Kidney hypoperfusion or adverse medication effects might explain the extremely high incidence of AKI in this series, but pathophysiologic effects of COVID-19 itself may play a role

Evidence of the extrapulmonary manifestations of COVID-19 continues to accumulate. In Annals of Surgery, Leon Naar, MD, research fellow in the Department of Surgery at Massachusetts General Hospital, Haytham M.A. Kaafarani, MD, director of trauma and emergency surgery research and of the Mass General Wound Center, and colleagues report that nearly three-quarters of patients admitted to the hospital early in the COVID-19 outbreak in Boston developed acute kidney injury (AKI).

Study Methods

The researchers prospectively collected data on 206 consecutive patients with COVID-19 (median age 60, 65% males) who were admitted to intensive care units (ICUs) at Mass General between March 13 and April 22, 2020.

Before hospital admission, 43% of patients had diabetes mellitus, 13% had chronic kidney disease and 3% were dialysis dependent.

Incidence of AKI

During hospitalization, 148 patients (72%) were diagnosed with AKI. In that subgroup, 43% were diagnosed on admission and 89% developed AKI by hospital day 6. Seventy patients in the AKI group (47%) had stage 3 disease, and 46 of them (66%) progressed to needing renal replacement therapy (RRT).

At the time the report was written, 27 patients who received RRT were still alive, including seven who remained hospitalized (two were still RRT-dependent). Five of the 20 patients discharged still required RRT.

Risk Factors

Independent predictors for the development of AKI were:

  • Male sex: OR, 4.42; 95% CI, 2.00–9.74; P < .001
  • Higher body mass index (BMI): OR, 1.08; 95 CI, 1.02–1.15; P = .006
  • Older age: OR, 1.03; 95% CI, 1.01–1.06; P = .047

Independent predictors of the need for RRT were:

  • Hypertension: OR, 3.15; 95% CI, 1.36–7.28; P = .007
  • Male sex: OR, 3.05; 95% CI, 1.09–8.50; P = .03
  • Higher BMI: OR, 1.06; 95% CI, 1.01–1.13; P = .03


Death rates were substantially higher in patients with AKI than those without:

  • ICU mortality: 28% vs. 5%; P < .001
  • In-hospital mortality: 33% vs. 9%; P < .001

Close Monitoring Warranted

Clinicians treating COVID-19 patients should monitor their renal function closely and intervene early if possible. Kidney hypoperfusion or adverse medication effects might account for the extremely high incidence of AKI in these patients, but pathophysiologic effects of COVID-19 itself, including cytokine storm and cell-mediated renal injury, may play a role.

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