RESUMEN
BACKGROUND: Childhood-onset rheumatoid arthritis (CORA), known as rheumatoid factor (RF)-positive juvenile idiopathic arthritis is a type of juvenile idiopathic arthritis that shares the same genetic factors and clinical features as adult-onset rheumatoid arthritis. In Africa, CORA hasn't been the subject of a specific study. OBJECTIVES: The aim of this study is to describe the clinical features, disease activity, functional disability, and treatment of CORA at diagnosis in Senegal and compare the findings to other CORA populations. METHODS: We conducted a mixed cohort study by reviewing the medical records of patients diagnosed with CORA with an age of symptom onset < 18 years according to the 2019 PRINTO provisional criteria for RF-positive JIA from January 2020 to December 2022 at rheumatology department of Aristide Le Dantec Hospital in Dakar, Senegal. We collected demographic, clinical, paraclinical and therapeutic data. Disease activity score was assessed by DAS28-ESR and DAS28-CRP. Functional disability was assessed using Health Assessment Questionnaire (HAQ) or Childhood HAQ. RESULTS: A total of 21 patients were included. Eighteen (85.7%) were Females. The mean age at symptom onset was 13.0 ± 3.0 years, and at diagnosis was 16.4 ± 4.2 years. Morning stiffness, joint swelling, and joint deformities were found in 20, 18 and 13 patients respectively. Four patients had a family history of rheumatoid arthritis. Five patients had extra-articular involvement such as rheumatoid nodules. Two patients had interstitial lung disease. The biological inflammatory syndrome was found in 90% of cases. 16 of 21 (76.2%) patients had positive RF, and 18 of 20 (90%) patients had positive Anti-CCP. Seven of 12 (58.3%) patients had positive anti-nuclear antibodies. The mean DAS28-ESR was 5.7 ± 1.0. Fifteen (71.4%) patients had high disease activity (DAS28-ESR > 5.1). The mean DAS28-CRP was 5.4 ± 1.1. The median HAQ was 2.12 with a mean HAQ of 1.9. Nineteen (90.5%) patients were treated with methotrexate, while 17 (81%) had a combination of methotrexate and hydroxychloroquine. Oral prednisone was used in 17 (81%) cases. Non-steroidal anti-inflammatory drugs were used in 4 cases (19%). After 6 months of treatment, mean DAS28-CRP was 2.9. CONCLUSION: In our study, CORA mainly affects 13-year-old girls, characterised by high disease activity with joint deformity and significant functional impairment. Treatment is mainly based on methotrexate, prednisone and hydroxychloroquine. Further studies are needed to determine the exact clinical phenotype of this disease.