FC067: Long-Term Outcome of Childhood Onset Idiopathic Nephrotic Syndrome

Abstract BACKGROUND AND AIMS Little is known about the long-term outcome during adulthood of childhood onset idiopathic nephrotic syndrome (INS). We aimed to determine which patients require long-term follow up after transition, to identify risk factors of relapse and to analyze treatment strategies. METHOD In this monocentric retrospective study, we included all patients admitted in our adult nephrology department with INS diagnosed during childhood. Patients who reached kidney failure during childhood were excluded. Data regarding the outcome at adult age were obtained through clinical database and medical charts. RESULTS Eighty-two patients (male/female = 2/1) were included, with a median age at diagnosis of 3.9 years (1.2–16.5). Sixty-eight patients had steroid-sensitive INS, including 52 with steroid-dependent nephrotic syndrome or frequently relapsing nephrotic syndrome. Fourteen patients had steroid-resistant nephrotic syndrome. A total of 89% of patients received corticosteroid sparing treatment during childhood. Median follow-up during adulthood was 6.2 (0.3–25) years. A total of 71% of patients experienced at least one relapse during adulthood. The total number of relapses during childhood and the number of relapses per year during childhood, reflecting disease activity, were significantly higher in patients who experienced relapses during adulthood than in patients who did not (Figure 1). The risk of relapse during adulthood was also significantly associated with the need for immunosuppressive regimen at the time of the transition visit (P = 0.002). To promote the successful transition of young people, we propose to organize a transition visit where the adolescent/young adult is seen jointly by pediatric and adult nephrologists, as it was done for 68% of patients in this study. The relapse rate was significantly lower (50%) in the subgroup of patients who had such a transition visit. We also found that relapse during the first two-years of adulthood follow-up was significantly associated with the risk of further relapse, highlighting the need for a close follow-up during the transition period. A total of 45% of patients received corticosteroid sparing treatment during adulthood, mainly mycophenolate mofetil (N = 23), calcineurin inhibitors (N = 21) and rituximab (N = 12). The main complications were high blood pressure (20/82, 26%) and osteopenia (19/26, 73% when bone densitometry was performed). Only one thrombo-embolic event and three severe infections were reported. At last follow-up, median eGFR was 87.1 (23.4–150.8) mL/min/1.73 m². CONCLUSION The incidence of relapses in adulthood is high in patients with active disease during childhood. A long-term follow-up is mandatory in these patients. Whereas renal function remained normal in most patients, high blood pressure and osteopenia were frequent and should be carefully monitored during adulthood. Transition visit should be carefully coordinated to prevent the risk of nonadherence.