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

Marta Calatroni ¹ Simeone Andrulli ² Federico Doti ³ Federica Bello ⁴ Giovanni De Vivo ⁵ Antonio Mastrangelo ⁶ Nicoletta Del Papa ⁷ Tommaso Schioppo ⁸ Laura Locatelli ¹ Francesco Reggiani ⁹ Gabriella Moroni ^1*

• ¹ Nephrology and Dialysis Division, Humanitas Research Hospital, Rozzano, Italy
• ² Associazione Italiana Ricercare per Curare ODV ETS (AIRpC), Lecco, Italy
• ³ Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Lombardy, Italy
• ⁴ Department of Experimental and Clinical Medicine, University of Florence, Florence, Tuscany, Italy
• ⁵ Humanitas University, Rozzano, Italy
• ⁶ Unit of Nephrology, Dialysis and Pediatric Transplant, Department of Woman-Child-Newborn, IRCCS Ca 'Granda Foundation Maggiore Policlinico Hospital, Milano, Lombardy, Italy
• ⁷ Department of Clinical and Community Sciences, Faculty of Medicine and Surgery, University of Milan, Milan, Lombardy, Italy
• ⁸ Santi Paolo e Carlo Hospital, Milano, Italy
• ⁹ Nephrology and Dialysis Division, IRCCS Humanitas Research Hospital, Via Manzoni 56, 20089, Rozzano, Milan, Italy

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. We aimed to establish differences in long-term kidney survival among lupus nephritis (LN) onset in children, adults, and elderly.Patients were categorized based on their age at lupus nephritis diagnosis: ≤18 years (childhood), >18 to <45 (adulthood), ≥45 years (elderly). Patients were categorized as having ≤18, >18-<45, ≥45 years at LN diagnosis. The three groups' CKD (eGFR<60ml/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 260 patients them, 46 (17.7%) were <18, 173 (66.5%) >18 and <45, and 41 (15.8%) >45 years old. Forty-six percent 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, while 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. Survival in elderly patients was significantly worse compared to children and adults (P= 0.001), whereas survival rates between children and adults were comparable (P = NS). At 5-,10-, and 20-years, CKD or death-free survival were 95,3%, 92,5%, and 88.4% in children, 98.2%, 90.1% and 82.6% in adults, and 87.5%, 67.8%, 53.5% in elderly (P=0.001; children vs adults P:ns). Age of LN onset and chronicity index at kidney biopsy were strongly correlated (P=0.001). At multivariate analysis, when chronicity index was excluded from the model, older age emerged as an independent predictor of CKD or death (Relative