Risk factors for acute kidney injury or mortality and long-term follow-up in coronavirus disease 2019 infected patients in the era before vaccination.

Background: Acute kidney injury (AKI) is a severe complication of coronavirus disease 2019 (COVID-19) and is associated with a higher risk of mortality. Understanding the risk factors contributing to COVID-19-related AKI and mortality before vaccination is important for the initiation of preventative measures and early treatment strategies.

Methods: This study included patients aged ≥18 years diagnosed with COVID-19 through polymerase chain reaction from May 2020 to July 2021, admitted in three local hospitals in Taiwan, with an extended follow-up until June 30, 2022. A median follow-up period of 250 days was used to assess AKI development and mortality. AKI was defined according to the Kidney Disease Improving Global Outcomes criteria. Multivarible Cox regression analysis of AKI and mortality-related risk factors were performed.

Results: Of the 720 hospitalized patients with COVID-19, 90 (22%) developed AKI. Moreover, 80%, 10.1%, and 8.9% of the patients had stage 1, 2, and 3 AKI, respectively. Patients with stage 1 to 3 AKI had significantly lower survival rates than those without AKI ( p = 0.001). The mean duration of post-admission AKI occurrence was 9.50 ± 11.32 days. Older age, hypoalbuminemia, and higher D-dimer and ferritin levels were associated with COVID-19 mortality. In COVID-19 AKI, in addition to older age and high D-dimer and ferritin levels, chronic kidney disease emerged as an independent risk factor.

Conclusion: COVID-19-related AKI develops early, exhibits a temporal association with respiratory failure, and is linked to an unfavorable prognosis. The mortality rate increased according to the AKI stage ( p = 0.001). Age, albumin, D-dimer, and ferritin levels, and the underlying chronic kidney disease status upon admission are crucial factors for predicting AKI development, which increases the mortality risk. Monitoring the renal function not only within 10 days of COVID-19 onset, but also within 1 month after the disease onset.