Long-term prognosis of lupus nephritis: comparison between pediatric, adult, and advanced age onset

Background and hypothesis: Lupus nephritis (LN) presents with varied outcomes depending on the age at diagnosis. We aimed to evaluate long-term kidney survival across three age groups. Methods: Patients were categorized based on their age at lupus nephritis diagnosis: <= 18 years (childhood), >18 to <45 (adulthood), and >= 45 years (elderly). The three groups' CKD (eGFR <60 ml/min/1.73 m(2) for at least 3 months) or death-free survival was estimated using Kaplan-Meier curves and compared with the log-rank test. To evaluate the independent prognostic role of age, adjusted for other predictors of chronic kidney disease (CKD) or death, we used multivariate Cox regression analysis. Results: This retrospective cohort study analyzed 260 patients followed for a median of 14.8 years. Of them, 46 (17.7%) were <18, 173 (66.5%) >18 and <45, and 41 (15.8%) >= 45 years old. 46% of elderly vs. 32.6% of children and 24.3% of adults had acute kidney disease (AKD) at diagnosis (P=0.02). Children had more active SLE, whereas the elderly had more chronic damage and hypertension. At 5, 10, and 20 years, CKD or death-free survival rates were 95.3%, 92.5%, and 88.4% in children; 98.2%, 90.1%, and 82.6% in adults; and 87.5%, 67.8%, and 53.5% in the elderly, respectively. Survival in elderly patients was significantly worse compared with children and adults (P= 0.001), whereas survival rates between children and adults were comparable (P = NS). At multivariate analysis, when the chronicity index was excluded from the model, older age emerged as an independent predictor of CKD or death (relative risk, RR: 3.278; CI: 1.402-7.662; P=0.006), with AKD (RR: 2.930; CI: 1.674-5.130; P<0.001), arterial hypertension (RR: 3.692; CI: 1.844-7.389; P<0.001), SLICC >0 (RR: 1.824; CI: 1.155-2.881; P=0.01), and failure to achieve complete remission at 1 year (RR: 4.784; CI: 2.355-9.716; P<0.001). Conclusion: While children and adults demonstrate comparable long-term kidney survival, elderly patients face significantly worse outcomes due to advanced chronicity and systemic damage. These findings highlight the need for tailored interventions in late-onset LN. Older-onset LN, in fact, was an independent predictor of CKD or death together with AKD, arterial hypertension, SLICC >0, and no remission at 1 year.