Factors determining resistance to conventional disease-modifying anti-rheumatic drug treatment in oligoarticular juvenile idiopathic arthritis

Objective Our study was designed to investigate the reasons for starting the conventional disease-modifying anti-rheumatic drugs (DMARDs) and the variables that impact the response to DMARD treatment in oligoarticular juvenile idiopathic arthritis (JIA) patients. Methods Oligoarticular JIA patients (n = 187) were categorized into two groups: Group A consisted of patients who achieved remission with DMARD, and Group B comprised those who did not respond to DMARD therapy. Results DMARDs were initiated for various reasons: 68 (36.4%) due to active disease despite nonsteroidal anti-inflammatory drugs (+/- intra-articular corticosteroid) treatment, 59 (31.6%) due to uveitis, 49 (26.2%) due to extended oligoarticular JIA, and 11 (5.9%) due to inflammatory bowel disease. One hundred twenty-three patients (65.8%) achieved remission with DMARDs (Group A), while 64 patients (34.2%) did not respond to DMARD therapy (Group B). In Group B, patients had higher C-reactive protein (CRP) levels as well as higher Juvenile Idiopathic Arthritis Disease Activity Scores-71 (JADAS-71) at diagnosis (both p < 0.001). Moreover, extended oligoarticular JIA subtype (p = 0.017) and involvement of small joints at diagnosis (p = 0.043) were more prevalent among these patients. Group A exhibited a higher frequency of antinuclear antibody positivity (p = 0.014). Elevated CRP levels (> 1.1 mg/dL) (OR 1.308, 95% CI 1.203-3.574; p < 0.001) and high JADAS-71 at diagnosis (> 15.8) (OR 1.659, 95% CI 1.179-2.941; p < 0.001) were associated with DMARD resistance. Conclusion Elevated CRP and high JADAS-71 at diagnosis were the main factors associated with DMARD resistance in oligoarticular JIA. Prospective long-term studies may help verify the role of these factors associated with DMARD resistance in oligoarticular JIA.