Prevalence and Risk Factors for Acute Kidney Injury in COVID-19-Hospitalized Patients in Poland Across Three Pandemic Periods.

Background/Objectives: Acute kidney injury (AKI) is a serious and prevalent complication of COVID-19. This study examines the prevalence, risk factors, and outcomes of AKI in hospitalized COVID-19 patients. Methods: We analyzed the data of 1223 adult COVID-19 hospitalized patients from a single district hospital during three pandemic periods: 3 November 2020-31 December 2020, 17 March 2021-8 May 2021, and 4 November 2021-21 February 2022. The analysis included demographic data, comorbidities, laboratory results, chest radiographs (CT lung scans), and outcomes. Results: We found an overall AKI incidence of 29.02%. AKI patients versus non-AKI ones were significantly older (median age 76.0 vs. 71.0, p < 0.001) and had more comorbidities, especially previous renal diseases, heart failure, coronary artery disease, and hypertension; they also significantly more often used diuretics, angiotensin receptor blockers (ARBs), and angiotensin-converting enzyme inhibitors (ACE-Is). AKI patients more frequently presented with abnormal CT lung scans and had higher white blood cell counts, lower lymphocytes percentages, higher C-reactive protein (CRP) levels, and lower platelet counts. They more often required oxygen therapy, more days of hospitalization, and had higher mortality rates. Conclusions: Older age, comorbidities, the use of diuretics, and renin-angiotensin system inhibitors (RASI) are key risk factors for AKI, which is consequently linked to a more severe disease course and poorer prognosis.