Patients with juvenile idiopathic arthritis (JIA) who do not demonstrate early responses to treatment with a new biologic agent after 3 months are less likely to achieve positive treatment responses, according to findings published in Arthritis Care & Research.
Researchers conducted a retrospective, longitudinal, cohort study using data from 4 trials to determine the probability of treatment response of 532 patients with JIA to 3 different classes of biologic disease-modifying antirheumatic drugs (bDMARDs) within 16 weeks. The 3 classes of biologic DMARDs were antitumor necrosis factor (anti-TNF), anti-interleukin 6 receptor (anti-IL6R), and selective co-stimulation modulating agents. Two trials assessed patient response to etanercept, while the other trials each assessed patient response to tocilizumab and abatacept. Approximately 70% of patients with JIA received concomitant methotrexate and 41% received prednisone.
The patients with JIA underwent repeated assessments every 4 weeks from baseline until trial completion. Assessments comprised 6 core measures selected by the American College of Rheumatology (ACR) to determine patient response to treatment. These 6 core measures included active joint count, limited range of movement joint count, physician assessment of global disease activity, parent/patient global well-being assessment, erythrocyte sedimentation rate, and assessment of functional ability per the Childhood Health Assessment Questionnaire.
The researchers classified children scoring 30 or below as nonresponders. Scores of 50 (ACR50) or above indicated clinically significant responses, which reflected improvements of 50% or more. They examined the 3 response categories of ACR50, ACR70, and ACR90. Secondarily, the researchers assessed disease activity using the 10-joint clinical Juvenile Arthritis Disease Activity Score (cJADAS10).
Overall, patients with JIA demonstrated a 0.698 probability of achieving ACR50 or above following 16 weeks of treatment with gradually declining probability of achievement after each month. After 1 month, patients who had not reached ACR50 had a 0.60 probability of achieving ACR50 by 4 months. After 3 months, patients who had not reached ACR50 had a 0.31 probability of achieving ACR50 by 4 months.
Factors predicting early positive responses to treatment according to ACR and cJADAS included age at diagnosis, disease duration, baseline rheumatoid factor, active joint counts, and concomitant methotrexate use.
Study limitations include the inability to generalize results to patient populations outside of those with polyarticular JIA and the small number of patients who receive treatment early in their disease course, which makes subgroup analysis difficult. The retrospective design, the heterogeneity of the 4 trials, and the inability to assess both late responders and response based on bDMARD mechanisms of action also limit the results of this study.
The study authors conclude, “JIA trial patients’ response following the start of a new bDMARD increased over the first 4 months.” They continue, “Our findings support the current treat-to-target recommendations to change treatment after 3 months if no clinically significant response was reached.”
Lim LSH, Lokku A, Pullenayegum E, Ringold S. Probability of response in the first 16 weeks after starting biologics: An analysis of juvenile idiopathic arthritis biologics trials. Arthritis Care & Research. Published August 17, 2022. doi:10.1002/acr.25003