Although case reports and observational studies suggest COVID-19 increases the risk of kidney diseases, real-world evidence comparing it with influenza is limited. Our study aims to assess the association between COVID-19 infections and subsequent kidney diseases, using influenza as a positive control and incorporating a negative control to establish clearer associations. A large retrospective cohort study with strata matching was conducted using the MarketScan database with records from Jan. 2020 to Dec. 2021. We used the ICD-10 codes to identify individuals and build three cohorts: (1) COVID-19 group, (2) Positive control group: Influenza but no COVID-19, and (3) Negative control group: no COVID-19 / Influenza. The outcomes were acute kidney injury (AKI), chronic kidney disease (CKD), end-stage renal disease (ESRD), and glomerular diseases. Multivariable stratified Cox proportional hazards regression analyses were performed. The study includes 939,241 individuals with COVID-19, 1,878,482 individuals in the negative control group, and 199,071 individuals with influenza. COVID-19 is significantly associated with increased risks of AKI (adjusted hazards ratio, aHR: 2.74; 95% CI, 2.61-2.87), CKD (aHR: 1.38, 1.32-1.45), ESRD (aHR: 3.22, 2.67-3.88), and glomerular diseases (aHR:1.28, 1.09-1.50), while influenza has no impact on CKD, ESRD, and glomerular diseases. Time-specific analyses indicate that COVID-19 has stronger effects on AKI in the short term but has stable long-term effects on CKD. In this large real-world study of working-age, commercially insured adults in the United States, COVID-19 infection is associated with a 2.3-fold risk of developing AKI, a 1.4-fold risk of CKD, and a 4.7-fold risk of ESRD compared to influenza. Greater attention to kidney diseases post-COVID-19 is essential to prevent future adverse health outcomes. COVID-19, caused by the SARS-CoV-2 virus, has been linked to multiple organ complications, with emerging evidence suggesting effects on kidney diseases. However, it is unclear how the risk of kidney disease after COVID-19 compares with influenza, another common viral infection. In this study, we analyzed commercial health insurance data from over three million working-age adults in the United States to compare individuals with COVID-19, those with influenza, and those with neither infection. We found that individuals who had COVID-19 were more likely to develop kidney problems, including short-term injury and long-term chronic disease. These findings suggest that COVID-19 may have a stronger impact on kidney diseases than influenza, highlighting the need for greater attention and monitoring of kidney function after COVID-19 infection. Zhang et al. utilized a large real-world dataset from more than three million adults in the United States to compare the incident of kidney disease risks following COVID-19 and influenza infections. The study found that COVID-19 is associated with a higher risk of acute kidney injury, chronic kidney disease, and end stage renal disease than influenza.
Zhang et al. (2026) studied this question.