The Association of Long COVID and CKD: Findings from the National Clinical Cohort Collaborative

Key Points – Baseline CKD, even mild, is associated with a higher risk of long coronavirus disease (COVID) in patients with acute severe acute respiratory syndrome coronavirus infection. Among those without CKD at baseline, Long COVID is associated with a higher risk of developing new CKD and faster kidney function decline. Associations between Long COVID and CKD/kidney function decline persist after matching, adjustment, and accounting for the competing risk of death. Background – Among patients with acute coronavirus disease-19 (COVID-19), the association of CKD and Long COVID has not been reported in large multicenter cohorts.Methods – This study used data from 59 health care systems across the United States, in the National Clinical Cohort Collaborative COVID enclave, to analyze the relationship between CKD and Long COVID among adults diagnosed with acute COVID-19 between October 2021 and September 2023. We conducted two main analyses. First analysis: we tested if baseline CKD (eGFR <60 ml/min per 1.73 m² or diagnostic code) or baseline ESKD are risk factors for Long COVID (identified using ICD-10-CM code U09.9). We secondarily assessed associations between baseline mild CKD (Stage 3a, eGFR 45–59 ml/min per 1.73 m²) and Long COVID. Second Analysis: among patients without baseline CKD/ESKD, we examined if incident CKD/ESKD and eGFR decline (≥20% in 1 year) were associated with Long COVID. We used propensity score matching for demographics and data contributing site, with models adjusted for risk factors and competing risk of death. All outcomes were evaluated within a 365-day follow-up period from the onset of acute COVID-19.Results – First analysis: From an unmatched cohort of 2, 385, 20 patients with acute COVID-19, those with baseline CKD/ESKD had a higher risk of Long COVID (adjusted subdistribution hazard ratio [sHR], 1.13; 95% confidence interval [CI], 1.09 to 1.18) after matching. A similar risk was noted even among those with mild CKD (sHR, 1.15; 95% CI, 1.05 to 1.25). Second Analysis: Among patients with acute COVID-19 and without baseline CKD/ESKD, Long COVID was associated with incident CKD/ESKD (sHR, 1.65; 95% CI, 1.51 to 1.81) and 20% or greater eGFR decline (sHR, 1.21; 95% CI 1.04 to 1.40) within 1 year.Conclusions – CKD, even mild, was associated with an higher risk of Long COVID. Among those without baseline CKD, Long COVID was associated with incident CKD and eGFR decline.