Effects of achieving simple disease activity index remission on joint space outcomes progression in early rheumatoid arthritis: an exploratory study using high-resolution peripheral quantitative computed tomography

Background: Rheumatoid arthritis is a chronic inflammatory disease with progressive joint destruction resulting in functional loss. High-resolution peripheral quantitative CT (HR-pQCT) is a novel technique for detailed volumetric assessment of joint space morphology and bone erosions. We hypothesized that effective control of inflammation in early rheumatoid arthritis (ERA) patients who can achieve sustained simple disease activity index (SDAI) remission will have less progression of joint damage and functional loss than patients who cannot achieve sustained SDAI remission (SDI). Objectives: To elucidate the effects of achieving SDI on the progression of joint space outcomes in patients with ERA assessed using HR-pQCT. Design: This was a prospective study with 109 participants receiving 1-year tight-control treatment aiming at SDAI remission. Methods: A total of 109 patients received 1-year tight-control treatment aiming at SDAI remission. SDI was defined as achieving SDAI remission at months 6, 9, and 12. The primary outcome was the change in joint space size and volume at metacarpophalangeal joints 2–4, determined using HR-pQCT at 12 months. Results: At 12 months, HR-pQCT image analysis showed that 14 out of 109 (12.8%) patients achieved SDI (SDI group). No significant differences in changes in joint space and erosion parameters were observed between the SDI and non-SDI groups. Erosion volume was reduced significantly in both groups. While new erosions (0% vs 16%, p = 0.338) and erosion progression (0% vs 27.3%, p = 0.592) were only observed in the non-SDI group, partial erosion healing was numerically more frequently observed in the SDI group (27.3% vs 10.3%, p = 0.260). At baseline, disease activity parameters were positively correlated with joint space parameters, while after 12 months, a negative correlation emerged between disease activity parameters and both mean joint space width (JSW) and minimum JSW. Conclusion: Although HR‑pQCT did not show a significant difference in joint damage progression at 12 months between patients with and without sustained remission, the overall cohort—managed with a tight-control strategy targeting SDAI remission—exhibited minimal bone and joint damage progression over 1 year.