Xinfeng Capsule combined with conventional Western medicine for rheumatoid arthritis: Efficacy, safety, and subgroup analysis in a multicenter real-world study

Rheumatoid arthritis (RA) is a progressive autoimmune disease with high disability rates and heavy economic burdens, affecting over 5 million Chinese adults. Conventional Western medicines have limitations, including 20% to 30% inadequate response, adverse effects, and high costs, while Chinese herbal compounds lack large-sample, long-term evidence. Xinfeng Capsule is based on traditional Chinese medicine (TCM) principles of "replenishing qi, clearing heat, resolving dampness, and dredging collaterals," is indicated for RA patients with qi deficiency and damp-heat obstruction syndrome, but its long-term real-world efficacy and safety need verification. Western medicine diagnosis adopted the 2010 American College of Rheumatology/European Alliance of Associations for Rheumatology criteria (≥3 of joint involvement, serological positivity, elevated inflammatory markers, or symptom duration ≥6 weeks). TCM diagnosis referenced the "Criteria for Diagnosis and Efficacy of TCM Diseases and Syndromes" for qi deficiency with damp-heat obstruction syndrome (≥2 main symptoms, ≥1 secondary symptom, and typical tongue/pulse signs). This retrospective multicenter study included hospitalized RA patients meeting the above criteria, divided into an experimental group (Xinfeng Capsule + conventional Western medicine) and a control group (conventional Western medicine alone). Statistical methods included independent samples t test/Mann-Whitney U test (baseline), paired t test/Wilcoxon signed-rank test (intra-group changes), and analysis of covariance (intergroup efficacy). Subgroup analyses were performed by rheumatoid factor (RF) levels and age; hepatorenal function and adverse events were monitored for safety. The experimental group showed significantly better outcomes: 2.68-fold greater reduction in joint pain Visual Analog Scale score (-3.0 ± 1.2 vs -1.12 ± 0.9 points, partial η2 = 0.241, P < .001), 1.35-fold greater disease activity improvement, and a more prominent mental health score increase (20.0 ± 5.3 vs 12.0 ± 4.8 points, P < .001). Subgroup analysis showed higher efficacy in patients with severely elevated RF (>500 IU/mL; effect size, 0.29 vs 0.207 in the normal RF group) and elderly patients (≥65 years, effect size, 0.131 vs 0.048 in the young group). No significant differences in abnormal hepatorenal indicators (alanine transaminase: 7.6% vs 6.8%; aspartate transaminase: 6.2% vs 4.8%; blood urea nitrogen: 2.8% vs 2.7%, all P > .05) or serious adverse events were observed between groups. Xinfeng Capsule combined with conventional Western medicine significantly improves pain and disease activity in RA patients, especially those with severely elevated RF and middle-aged/elderly populations, without increasing hepatorenal risks. It provides high-quality real-world evidence for integrated TCM-Western treatment of RA and supports Xinfeng Capsule's clinical application.