Efficacy, mechanisms, and influence factors of small molecule targeted therapy in treating rheumatoid arthritis: a multi-dimensional clinical, immunological, and ultrasonographic study

Background Targeted synthetic disease-modifying antirheumatic drugs (tsDMARDs) show promise for rheumatoid arthritis (RA), but multi-dimensional efficacy evaluation needs further study. Objective This study aimed to comprehensively assess tsDMARDs’ efficacy in RA and explore factors linked to treatment response. Methods 123 consecutive active RA patients treated with tsDMARDs for ≥6 months at Suzhou Ninth People’s Hospital (January 2023–December 2024) were retrospectively analyzed; 120 were included after exclusions. Clinical efficacy was appraised using the Disease Activity Score in 28 joints based on C-reactive protein (DAS28-CRP), Clinical Disease Activity Index (CDAI), American College of Rheumatology 20/50/70 (ACR20/50/70), and the overall effective rate. Immunological parameters included erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), and anti-citrullinated protein antibody (ACPA). Musculoskeletal ultrasound parameters consisted of synovial hypertrophy score assessed by gray-scale ultrasound (GSUS) and synovial vascularity grade assessed by power Doppler ultrasound (PDUS). Correlations between parameters were analyzed, and multivariate logistic regression pinpointed independent risk factors of favorable therapeutic response. Results Among 120 patients, patients were stratified into effective (n = 78) and non-effective (n = 42) groups, with comparable baseline characteristics (all P > 0.05). After 6 months, the effective group showed significantly greater improvements in DAS28-CRP, CDAI, ESR, CRP, RF, ACPA, GSUS, and PDUS (all P < 0.001). Positive correlations were present between immunological/ultrasound parameters and disease activity scores. Multivariate logistic regression identified reduced PDUS signal, lower CRP, and improved DAS28-CRP as independent predictors of favorable response. Conclusion tsDMARDs effectively improve joint symptoms, reduce disease activity, and enhance articular function in RA patients, potentially supporting personalized therapeutic strategies.