A RWS of SC MTX in Chinese RA Patients

Design: A prospective, single-arm, multicenter, real-world study that does not interfere with the patient's treatment plan Primary Objective: 1\. To evaluate the effectiveness and safety of subcutaneous Methotrexate (MTX) in RA patients in a real-world setting; Exploratory Objectives: 1. To assess the safety and effectiveness of subcutaneous MTX in RA patients with interstitial lung disease (ILD) or interstitial lung abnormalities (ILAs), and stable coronary artery disease (SCAD) in a real-world setting; 2. To evaluate the effectiveness and safety of subcutaneous MTX in RA patients with different clinical subtypes. The study includes adult RA patients treated with subcutaneous MTX, divided into the following four cohorts based on comorbidities and clinical subtypes: Cohort 1: Chinese RA patients receiving subcutaneous MTX treatment (8,000 cases) Cohort 2: Chinese RA patients with ILD or ILAs receiving subcutaneous MTX treatment (200 cases) Cohort 3: Chinese RA patients with clinical subtype results at enrollment, receiving subcutaneous MTX treatment (1,500 cases) Cohort 4: Chinese RA arthritis patients with SCAD receiving subcutaneous MTX treatment (300 cases)