Clinical and laboratory differences in pediatric-onset versus adult-onset lupus nephritis: A retrospective cohort analysis.

IntroductionLupus nephritis (LN) is a severe manifestation of systemic lupus erythematosus (SLE) and is associated with significant morbidity and mortality. However, the course of LN that develops at a younger age is less well understood. Therefore, we evaluated the clinical and laboratory characteristics of adult LN patients and compared them, depending on whether the disease started in childhood (pediatric-onset LN [pLN]) or in adulthood (adult-onset LN [aLN]).Patients and MethodsWe retrospectively analyzed the medical records of all adult LN patients treated at the University Hospital in Kraków, Poland, from 2012 to 2022. All included patients met the European League Against Rheumatism/American College of Rheumatology criteria for SLE from 2019.ResultsAmong 343 LN patients, pLN was stated in 46 cases (13.41%). pLN and aLN had a comparably high female-to-male ratio (6.67 vs 4.82, respectively; p = 0.07) and similarly often presented with more advanced kidney involvement in histology. In turn, lupus malar rash and serositis were more frequent in pLN than aLN (p = 0.048 and p = 0.015, respectively). End-stage kidney disease (ESKD) was documented in pLN patients 2.72 times more frequently (p = 0.036); however, the person-year rate did not differ. Interestingly, in pLN we reported a more common presence of anti-cardiolipin antibodies in the IgM class (p = 0.042). The occurrence of other SLE-specific autoantibodies did not differ between both analyzed groups. Regarding immunosuppressive treatment, glucocorticosteroids were the most frequently utilized in both subgroups. Still, pLN cases were more frequently treated with chloroquine or hydroxychloroquine, azathioprine, and immunoglobulins than aLN patients (p < 0.05, for all).ConclusionspLN is characterized by more severe SLE clinical manifestations. Therefore, SLE patients who developed LN in childhood likely require more aggressive immunosuppressive treatment.