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.