Abstract
Objectives: Rheumatoid factor (RF) binds to the immunoglobulin Fc portion, which might influence the efficacy of Fc-carrying TNF inhibitors (TNFi). This has been shown in studies of adults with RF-positive RA, but not yet in children.
The aim of this study was to determine efficacy of TNFi in children with seropositive polyarthritis according to rheumatoid factor levels.
Methods: A database was searched for patients with JIA/seropositive polyarthritis, admitted between January 2019 and March 2023. Data collected were demographic data, treatment with antirheumatic medications and JADAS and cJADAS prior to and after start of TNFi treatment. Changes in JADAS and cJADAS on TNFi were compared between patients with RF < 150 U/ml and RF ≥ 150 U/ml using repeated measures ANOVA.
Results: 17 patients were included, 8 with RF < 150 U/ml at diagnosis, and 9 with RF ≥ 150 U/ml. 16 patients (94%) were treated with etanercept, and one with golimumab, 15 patients were additionally treated with methotrexate. Mean JADAS (cJADAS) at treatment start was 26.0 ± 16.9 (24.4±13.7), and 5.5 ± 6.0 (5.1±5.7) at assessment after starting TNFi. A repeated-measures ANOVA determined that mean JADAS and cJADAS scores did not differ significantly across the two time points.
Conclusions: Unlike in adults, efficacy of TNFi was not diminished by elevated levels of RF in this cohort of pediatric patients with seropositive polyarthritis. Further studies are necessary to confirm these findings.