Effect of Achieving Sustained SDAI Remission on Erosion Healing in Early Rheumatoid Arthritis - A One-year Prospective HR-pQCT Study

Abstract

Background Rheumatoid arthritis (RA) is a chronic inflammatory disease with progressive joint destruction. High-resolution peripheral quantitative CT (HR-pQCT) is a novel technique for detailed bone microstructure analysis allowing volumetric assessment of bone erosions. While most patients demonstrating little baseline joint damage on radiography in the early stage of RA, whether achieving simple disease activity index (SDAI) remission can lead to better structural outcome is to be confirmed. Methods Patients with ERA were recruited and treated to the target of simple disease activity index (SDAI) remission using a standardized algorithm. One hundred patients who received the one-year tight-control treatment were grouped by achieving SDAI sustained LDA [SDAI [Formula: see text] at 6, 9 and 12 months (sLDA group) or not (non-sLDA group). HR-pQCT of the second to fourth metacarpophalangeal joints were performed at baseline, month 6 and one-year. Erosion volume and marginal bone mineral density (BMD) were measured. On an individual patient basis, erosion progression was defined as at least one erosion showing (1) an increase in erosion volume exceeding the smallest detectable change [SDC] (0.08 mm 3) AND (2) a decrease in marginal BMD exceeding SDC (7.8 mmHA/cm 3). Erosion healing was defined as at least one erosion showing (1) a reduction in erosion volume greater than SDC AND an increase in BMD exceeding SDC OR complete disappearance of the lesion AND (2) the absence of any erosion progression. Results Fourteen patients (12.8%) achieved sustained SDAI remission from 6-12 months (SDI group). After 12 months, a significant reduction in erosion volume and marginal osteosclerosis was observed in both groups. The SDI group showed a lower incidence of erosion progression (increase in volume [Formula: see text]0.08mm 3 and decrease in marginal osteosclerosis [Formula: see text]7.8mg HA/cm 3 : 0% vs 16%, p=0.135) and exhibited a higher rate of erosion healing (56% vs 29%, p=0.083) compared with the non-SDI group. In the GEE model, patients in the SDI group showed a higher likelihood of erosion healing (OR: 2.976, 95% CI: 1.0 - 8.9, p=0.050). The changes in erosion depth and width were similar between two groups. Conclusion Achieving sustained SDAI remission could improve erosion healing and limit erosion progression in patients with ERA.