Risk stratification for chronic kidney disease progression after COVID-19: insights from multivariate modeling

Abstract

SUMMARY Objectives. Chronic kidney disease and COVID-19 have a bidirectional interaction: on one hand, it increases the risk of severe COVID-19, while SARS-CoV-2 may accelerate renal deterioration in vulnerable patients. We aimed to assess medium-term renal status after COVID-19 and to identify independent unfavorable prognostic factors for chronic kidney disease progression using multivariate regression models. Methods. In a prospective cohort study, 280 pre-dialysis patients (KDIGO stages G1–G5) were evaluated in a tertiary nephrology center. Participants were allocated to two matched groups: post-COVID-19 patients with chronic kidney disease (n=140) and non-COVID control patients with chronic kidney disease (n=140), comparable for age, sex, disease stage, and major comorbidities. Clinical variables, renal and metabolic parameters (including proteinuria, phosphate, and hemoglobin), inflammatory markers, and SF-36 quality-of-life scores were collected at follow-up. Group comparisons, correlation analyses, and multivariate logistic regression were performed. Advanced chronic kidney disease was defined as stage G4–G5 at follow-up. Results. Post-COVID and control groups showed similar renal function at follow-up (mean eGFR ≈35 mL/min/1.73m2; p>0.5), with no significant differences in serum creatinine, urea, or proteinuria prevalence. Inflammatory markers were mildly elevated and comparable between groups, consistent with chronic kidney disease related inflammation. SF-36 scores were broadly similar; post-COVID patients reported lower vitality (fatigue) but slightly better social functioning. Within the post-COVID cohort, multivariate logistic regression identified three independent predictors of advanced chronic kidney disease: proteinuria (adjusted OR 5.0; 95% CI 2.0–12.5; p<0.001), serum phosphate (OR 1.8 per +1 mg/ dL; 95% CI 1.3–2.5; p<0.001), and hemoglobin (OR 1.4 per −1 g/dL; 95% CI 1.1–1.8; p=0.005). Model performance was strong (Hosmer–Lemeshow p=0.45; AUC ≈0.88). Conclusions. COVID-19 history did not uniformly worsen medium-term renal outcomes in chronic kidney disease patients compared with matched non-COVID controls. However, persistent proteinuria, hyperphosphatemia, and anemia independently identified post-COVID patients at higher risk of advanced chronic kidney disease, supporting intensified post-COVID nephrology follow-up focused on these markers.