Disease features at diagnosis and changes in disease course severity among commercially insured patients with childhood-onset compared with adult-onset systemic lupus erythematosus.

Introduction: Systemic lupus erythematosus (SLE) causes widespread inflammation and damage in affected organs. Severity is determined by the type of organ systems affected and the extent of involvement. SLE occurs in childhood or adulthood and disease severity varies according to age of onset. We compared disease features and changes in disease severity over time between childhood-onset (cSLE) and adult-onset SLE (aSLE).

Methods: Patients 0-64 years old, newly diagnosed with SLE during 2014-2020 were identified using the MarketScan® database. A validated algorithm was used to assess disease severity. Improving severity versus baseline was defined as a transition from a higher (severe) to a lower (mild/moderate) disease state during each evaluation period. Group comparisons were made using the Pearson chi-square test for categorical and t test for continuous measures.

Results: A total of 10,912 patients were included. Most (89.9%) were female with a mean age of 14.2 versus 44.6 years for cSLE and aSLE groups, respectively. Patients with cSLE were more likely to have severe disease at diagnosis (38.3% vs 10.7%; p < .0001) versus aSLE. The largest reduction in SLE severity occurred during 6 to <12 months post-index with cSLE experiencing the greatest improvement (36.7% vs 19.9%; p < .0001) compared with aSLE. However, despite improvements observed over time in cSLE, this group was still more likely to have severe disease at 0 to <6 months (26.4% vs 10.5%) and 6 to <12 months (14.4% vs 8.6%) post-index compared with aSLE patients (p < .01, all). For aSLE, the proportions of patients experiencing either an improvement or deterioration in symptoms was similar during 0 to <6 months and 6 to <12 months. However, during 12 to <24 months, nearly twice as many patients in this group experienced a deterioration in symptoms (30.1%) compared to improvement (15.6%).

Conclusions: Children with SLE present with greater symptom severity compared with adults. Although children were more likely to experience improvements following treatment, they had more active disease over time than aSLE patients. Disease severity remained stable for aSLE patients until the second year of follow-up, when more patients experienced a deterioration rather than improvement in symptoms.