Clinical Determinants of Childhood Onset Systemic Lupus Erythematosus among Early and Peri-Adolescent Age Groups

Introduction: Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease that is associated with significant morbidity and mortality. SLE disproportionately affects women and minorities. Childhood-onset SLE (cSLE) in particular tends to be more aggressive than adult-onset SLE. Despite substantial improvements in the treatment of cSLE, there is significant variability in treatment responses and long-term outcomes. Furthermore, there is a paucity of studies involving cSLE, and in particular, cSLE among different age groups. The aim of this study was to test the hypothesis that an early-onset cSLE cohort would demonstrate unique characteristics with distinctive clinical and laboratory features at disease onset. We specifically investigated whether clinical, epidemiological, or serological factors are differentially associated with early- and late-onset cSLE. This could have direct impact on clinical management with the goal of improving outcomes and quality of life for children with SLE. Methods: Our study was conducted at a large tertiary center. We included 213 subjects seen at our pediatric rheumatology clinic aged 4–17 years. Epidemiologic, clinical phenotype, disease severity, serology, treatment, and outcome data were compared between subjects with cSLE onset prior to 10 years of age (early-onset disease, n = 43) and those with cSLE onset greater than 10 years of age (peri-adolescent disease, n = 170). We compared clinical features between early- and peri-adolescent onset cSLE in order to investigate the association between age at disease onset of cSLE and clinical disease expression and outcomes. Results: Of the 213 subjects with cSLE in our study, 43 subjects had early-onset disease (age 2 to ≤9 years) and 170 patients had peri-adolescent onset disease. We found that early-onset cSLE was associated with a higher prevalence of positive anti-dsDNA antibody at cSLE diagnosis, higher anti-dsDNA antibody titer at cSLE diagnosis, rash, and azathioprine use (p < 0.001, p = 0.004, p = 0.011, and p = 0.008, respectively). In contrast, we found that peri-adolescent onset cSLE (≥10 years of age) was associated with worse disease activity (SLEDAI range 0–24) (p < 0.001), higher SLICC at diagnosis (p < 0.001), as well as a higher rate of mycophenolate mofetil and hydroxychloroquine use (p = 0.003 and p < 0.001, respectively). There were no significant differences in the prevalence of neuropsychiatric symptoms or the development of Class IV/Class V lupus nephritis between the early-onset and peri-adolescent groups.