Changes in kidney health before, during, and after the COVID-19 pandemic: a nationwide serial cross-sectional study in Korea.

Abstract

Objectives: The population-level kidney consequences of the COVID-19 pandemic beyond confirmed infections remain uncertain. We examined temporal changes in chronic kidney disease (CKD), proteinuria, and kidney function in a nationally representative Korean population.

Methods: We analyzed serial cross-sectional data from the Korea National Health and Nutrition Examination Survey (2017-2024), including adults aged ≥19 years with serum creatinine and proteinuria measurements. We classified survey periods as pre-pandemic (2017-2019), pandemic (2020-2021), and post-pandemic (2022-2024). Survey-weighted logistic and linear regression models were used to examine associations of pandemic period with CKD, proteinuria, and estimated glomerular filtration rate (eGFR), adjusting for demographic, socioeconomic, metabolic, and lifestyle factors. We also conducted age-stratified analyses.

Results: The analysis included 44,831 adults (mean age, 52.8 years; 44.5% men). CKD prevalence rose from 4.65% before the pandemic to 7.88% during and 7.49% after it; proteinuria prevalence nearly doubled (3.27%, 6.68%, and 6.18%, respectively). Relative to the pre-pandemic period, the adjusted odds of CKD were higher during (odds ratio [OR], 1.22; 95% confidence interval [CI]: 1.09-1.37) and after (OR, 1.24; 95% CI: 1.10-1.39) the pandemic. The corresponding associations were larger for proteinuria (OR, 1.34; 95% CI: 1.17-1.53 and OR, 1.33; 95% CI: 1.17-1.51, respectively). Changes in eGFR were minimal, with no significant temporal trend. Associations were strongest among middle-aged and older adults, particularly for proteinuria among adults aged ≥65 years.

Conclusion: CKD prevalence increased during and after the COVID-19 pandemic, largely reflecting a sustained increase in proteinuria rather than a decline in eGFR. These findings support ongoing kidney surveillance and measures to reduce cardiometabolic risk, particularly among middle-aged and older adults.