Systemic Inflammatory Diseases in Children with Sickle Cell Disease: A French Multicenter Observational Study on Diagnostic and Therapeutic Issues.

Background: Systemic inflammatory diseases (SIDs) have been reported in patients with sickle cell disease (SCD), but clinical data in children are scarce.

Objectives: To identify clinical and laboratory features at diagnosis of SID in children with SCD and to describe their evolution.

Methods: Data from children with SCD and SIDs were retrospectively collected in a French multicenter study from 1991 to 2018. Information included clinical characteristics, inflammatory markers, autoantibodies patterns, treatments, and complications. Inflammatory marker levels were compared at SID diagnosis and at the last follow-up. Statistical analyses were performed using Cran R software.

Results: Among a cohort of 3800 children with SCD, 43 SIDs were identified in 35 study participants: autoimmune liver disease (AILD, n = 13), inflammatory bowel disease (IBD, n = 7), juvenile idiopathic arthritis (JIA, n = 6), systemic lupus erythematosus (n = 4), autoimmune hemolytic anemia (n = 3), Sjögren syndrome (n = 1), histiocytic necrotizing lymphadenitis (n = 2), vasculitis (n = 2), myasthenia gravis (n = 1), sarcoidosis (n = 1), idiopathic inflammatory granulomatous uveitis (n = 1), mixed connective tissue disease (n = 2). Prevalence of SID was 0.9% in our cohort of children with SCD. The median time between initial symptoms and SID diagnosis was 10 (3-20) months, notably longer in children with JIA, IBD, and Sjögren syndrome. Sixteen patients (46%) exhibited hypergammaglobulinemia (>20 g/L) at diagnosis. No significant differences were observed for other inflammatory parameters. Twenty-one children (60%) received systemic steroids and 13 (37%) biological therapies. Three patients (9%) underwent hematopoietic stem cell transplantation. Nine patients (26%) had severe infections; one died.

Conclusion: Delayed diagnosis was frequent due to overlapping clinical presentations between SCD and SID. Clinicians must be aware of warning signs associated with elevated inflammatory markers, hypergammaglobulinemia, or specific antibodies. Therapeutic strategies remain challenging.