Prevalence and risk factors for acute kidney injury at the diagnosis of juvenile idiopathic arthritis in children and its long-term implications for kidney health

Background: We aimed to investigate the prevalence and risk factors of acute kidney injury (AKI) at juvenile idiopathic arthritis (JIA) onset and its impact on long-term kidney outcomes. Methods: In this multicenter study, we retrospectively reviewed 192 children diagnosed with JIA (1998–2025). AKI was defined according to KDIGO serum creatinine criteria. Kidney damage (KD) was defined as chronic kidney disease (CKD) and/or hypertension at follow-up. Logistic and Cox regression analyses were used to identify risk factors and to calculate odds ratio (OR) and hazard ratio (HR), respectively. Kaplan–Meier analysis evaluated KD-free survival. Results: At JIA onset, 45 patients (23.4%) developed AKI, mostly stage 1, with no cases requiring dialysis. Independent predictors of AKI were younger age, elevated C-reactive protein, and ANA positivity. After a mean follow-up of 6.3 years (range 1–27.5), 23 patients (12%) developed KD (19 CKD, 4 hypertension, 2 both). Patients with AKI at onset had a significantly higher risk of KD (OR 5.8, 95% CI: 2.4–15.2; HR 3.7, 95% CI: 1.9–8.9). At 25.1 years of age, the cumulative proportion free from KD was 26.9% in patients with AKI versus 64.1% in those without (p = 0.005). Conclusions: AKI is relatively frequent at JIA onset and represents a strong predictor of long-term kidney damage. Early recognition and careful follow-up of children with AKI may help identify those at greatest risk for adverse kidney outcomes.