Renal relapse in children and adolescents with childhood-onset lupus nephritis: a 20-year study

There is little data on renal relapse in childhood-onset lupus nephritis (cLN). We investigate the incidence, predictive factors and outcomes related to renal relapse.We conducted a retrospective cohort study of all cLN diagnosed ≤18 years, between 2001-2021, to investigate the incidence and outcomes related to renal relapse.95 Chinese cLN patients (91% proliferative LN) were included. Induction immunosuppression was prednisolone and cyclophosphamide (n = 36, 38%) or mycophenolate mofetil (MMF, n = 33, 35%). Maintenance immunosuppression was prednisolone and MMF (n = 53, 54%) or azathioprine (AZA, n = 29, 31%). The rates of complete/partial remission at 12-month were 78.9%/7.4%. 70 renal relapses occurred in 39 patients over a follow-up of 10.2 ± 5.9 years (0.07 episode per patient-year). Relapse-free survival was 94.7%, 86.0%, 80.1%, 71.2%, 68.3%, 50.3%, and 44.5% at 1-, 2-, 3-, 4-, 5-, 10-, and 20-year, respectively. Multivariate analysis showed that LN diagnosis <13.1 years (HRadj 2.59, 95% CI 1.27-5.29, p= 0.01), AZA maintenance (HRadj 2.20, 95% CI 1.01-4.79, p= 0.05), partial remission (HRadj 3.9, 95% CI 1.03-9.19, p= 0.01) and non-remission (HRadj 3.08, 95% CI 1.35-11.3, p= 0.04) at 12-month were predictive of renal relapse. Renal relapse was significantly associated with advanced chronic kidney disease (stage 3-5) and end-stage kidney disease (17.9% vs 1.8%, p< 0.01). Furthermore, patients with renal relapse(s) showed increased incidence of infections (30.8% vs 10.7%, p= 0.02), osteopenia (38.5% vs 17.9%, p= 0.04) and hypertension (30.8% vs 7.1%, p< 0.01).Renal relapse is common among cLN especially among young patients, and is associated with increased incidence of morbidity and mortality. Attaining complete remission and the use of MMF appear to have reduced the incidence of renal relapses.