Changes of Acute Kidney Injury Epidemiology during the COVID-19 Pandemic: A Retrospective Cohort Study

Abstract

To evaluate the impact of the Coronavirus Disease-19 (COVID-19) pandemic on the epidemiology of acute kidney injury (AKI) in hospitalized patients, we performed a retrospective cohort study comparing data of patients hospitalized from January 2016 to December 2019 (pre-COVID-19 period) and from January to December 2020 (COVID-19 period, including both severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-negative and positive patients). AKI was classified by evaluating the kinetics of creatinine levels. A total of 51,681 patients during the pre-COVID-19 period and 10,062 during the COVID-19 period (9026 SARS-CoV-2-negative and 1036 SARS-CoV-2-positive) were analyzed. Patients admitted in the COVID-19 period were significantly older, with a higher prevalence of males. In-hospital AKI incidence was 31.7% during the COVID-19 period (30.5% in SARS-CoV-2-negative patients and 42.2% in SARS-CoV-2-positive ones) as compared to 25.9% during the pre-COVID-19 period (p < 0.0001). In the multivariate analysis, AKI development was independently associated with both SARS-CoV-2 infection and admission period. Moreover, evaluating the pre-admission estimated glomerular filtration rate (eGFR) we found that during the COVID-19 period, there was an increase in AKI stage 2−3 incidence both in patients with pre-admission eGFR < 60 mL/min/1.73 m2 and in those with eGFR ≥ 60 mL/min/1.73 m2 (“de novo” AKI). Similarly, clinical outcomes evaluated as intensive care unit admission, length of hospital stay, and mortality were significantly worse in patients admitted in the COVID-19 period. Additionally, in this case, the mortality was independently correlated with the admission during the COVID-19 period and SARS-CoV-2 infection. In conclusion, we found that during the COVID-19 pandemic, in-hospital AKI epidemiology has changed, not only for patients affected by COVID-19. These modifications underline the necessity to rethink AKI management during health emergencies.

Keywords: COVID-19; SARS-CoV-2; acute kidney injury; hospitalization; mortality.

Figure 1

Incidence and staging of in-hospital AKI. Comparison of AKI incidence and stages between patients hospitalized in the pre-COVID-19 period (2016–2019) vs. COVID-19 period (2020). Patients of the COVID-19 period were also divided according to SARS-CoV-2 positivity to nasopharyngeal swab. * p < 0.0001 vs. pre-COVID-19; § p < 0.0001 vs. pre-COVID-19 and SARS-CoV-2 negative. Abbreviations: AKI—acute kidney injury; COVID-19—Coronavirus Disease-19; SARS-CoV-2—severe acute respiratory syndrome coronavirus 2. The different groups were compared by ANOVA with post-hoc testing.

Figure 2

Kaplan–Meier curves of overall survival without death for hospitalized patients (2016–2020) based on the presence of AKI, admission period and/or SARS-CoV-2 infection. Solid lines represent patients who develop AKI, while dashed lines represent patients who did not develop AKI. The grayscale reveals the different admission period and the SARS-CoV-2 infection status (dark gray: pre-COVID-19 period; light gray: SARS-CoV-2-negatives admitted in COVID-19 period; black: SARS-CoV-2 positive admitted in COVID-19 period). Log-rank test p < 0.001. Abbreviations: AKI—acute kidney injury; COVID-19—Coronavirus Disease-19; SARS-CoV-2—severe acute respiratory syndrome coronavirus 2.