Autoimmune thyroid diseases, autoimmune hepatitis, celiac disease and type 1 diabetes mellitus in pediatric systemic lupus erythematosus: Results from the CARRA Legacy Registry

Objective: Polyautoimmunity (PA) with systemic lupus erythematosus (SLE) is reported as a poor prognostic factor, but little is known about its effect in childhood-onset SLE (cSLE). We describe PA in cSLE within the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Legacy Registry and evaluate its association to lupus disease outcomes.

Methods: CARRA Legacy Registry is the largest pediatric rheumatology registry that collected data at enrollment and every 6 months thereafter. We describe the co-occurrence of selected autoimmune disorders (autoimmune thyroid diseases, autoimmune hepatitis, celiac disease and type 1 diabetes mellitus) in cSLE. To assess outcomes, we studied measures of lupus disease activity, complications, and patient's quality of life (QoL). Comparisons by PA status were made using chi-square, Fisher's exact test, two-sample t-tests, Wilcoxon rank sum tests, and mixed effects models as appropriate.

Results: 1285 patients met the American College of Rheumatology criteria for SLE. Of those, 388 (30%) had data on comorbidity. The prevalence of PA was 8.8%. Patients with PA reported more hospitalizations and aggressive immunotherapy use. SLEDAI and PGA scores improved over time, but did not differ by PA status. No significant differences were found in QoL measures or their trajectory over time by PA status.

Conclusion: In cSLE, PA is associated with more hospitalizations and aggressive immunotherapy use. Although lupus disease activity improved over time, patients' QoL neither improved over time nor differed by having other autoimmune disease. Prospective, case-control, long-term follow-up studies on cSLE are needed to validate our results.

Mesh key indexing terms: Pediatric systemic lupus erythematosus; Autoimmune diseases; Outcome assessment.

Keywords: Systemic lupus erythematosus; renal lupus; thrombosis.