Background/Purpose: JIA, a common childhood arthropathy, with an estimated prevalence of 1 in 1000 in children under the age of 16, affects children of all ages and races.  There is limited data describing the characteristics of JIA in African-American (AA) children.  The purpose of this study was to compare phenotypic characteristics of AA and Non-Hispanic White (NHW) JIA patients in our rheumatology clinic.  

Methods: Charts of children with JIA, who were enrolled in a genetic study between June 2009 and June 2012 were reviewed.  At time of enrollment, demographic and disease-related data were collected. Patients who identified as Hispanic or multi-racial were excluded. Disease characteristics compared between AA and NHW children included:  age at onset and diagnosis, family history, JIA subtype, laboratory tests, associated features, medications, and radiographic changes.  Fischer’s exact test or Chi-Square tests were used to compare nominal variables, and student’s T test was used to compare continuous variables.

Results: 150 NHW children and 62 AA children with JIA were studied.  Table 1 compares demographic and disease characteristics of NHW and AA children.  AA children with JIA were significantly older both at disease onset and presentation to a pediatric rheumatologist.  JIA subtypes differed significantly between AA children and NHW children, with the AA being predominantly polyarticular RF+, and NHW being predominantly persistent oligoarticular. Both groups had a female predominance.  Significantly more AA children had Medicaid and lived closer to their rheumatologist. AA children were less likely to have a family history of autoimmunity. Laboratory studies demonstrated that AA children were more likely to have positive RF and CCP antibodies. AA children were more likely to be treated with methotrexate at diagnosis, and more likely to have received systemic steroids during the course of their disease.  These children were also more likely to have joint space narrowing and osteopenia on x-ray than NHW children. AA children were more likely to have rheumatoid nodules and chronic anemia as manifestations of their disease. The prevalence of uveitis was not significantly different between AA and NHW children with JIA. Even excluding the polyarticular RF+ subtype, AA children were older at onset and had more cumulative joints affected.

Conclusion: Using a large cohort of AA and NHW children with JIA, we confirm reports of the differences in disease characteristics reported in smaller earlier studies. AA children with JIA demonstrate significant differences in disease characteristics; they are older at disease onset, more likely to have RF/CCP + polyarthritis, more likely to use systemic steroids, more likely to have a higher joint count involvement, and more likely to have radiographic evidence of disease.  These observations support earlier observations that the phenotype of JIA is different in AA children.