The risk of kidney disease increases following SARS-CoV-2 infection compared to influenza

Background: 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. Methods: 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. Results: 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. Conclusions: 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.