The role of X-ray imaging and musculoskeletal ultrasound in the diagnosis and management of rheumatoid arthritis

Abstract: Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease characterized by symmetric joint inflammation that often involves the small joints of the hands and feet, with progressive destruction, deformity, and disability of the joints. Small joints of the hands and feet are frequently the first to be involved in RA, which is why methods for assessment of these joints are of particular importance at the onset of RA and early stage of the disease. The results of this thesis have highlighted the role of conventional radiography, Digital X-ray radiogrammetry (DXR) and musculoskeletal ultrasound (MSUS) in the diagnosis and management of RA. Paper I is based on the study about clinical and radiographic outcomes in patients with early RA who responded well to initial Methotrexate (MTX) monotherapy. Most early RA patients who achieved low disease activity after 3 – 4 months of MTX monotherapy continued to have low disease activity during 2 years follow-up. However, marked radiographic progression occurred in a proportion of patients, even despite sustained DAS28 remission. Paper II aimed to evaluate whether a significant decrease of cortical bone mineral density (BMD) measured by DXR during the first year of RA correlated with radiographic progression after 2 years. The results indicated that patients with significant decrease of DXR-BMD had significantly greater risk for radiographicprogression, compared with patients without. Evaluation of RA patients with significant decrease in DXR-BMD during the first year of the disease helps to identify patients with higher risk for radiographic progression later in the disease course. However, future studies should investigate whether decrease in DXR-BMD during the first 3 or 6 months of the disease could indicate the same results. Paper III is based on a study about clinical predictors at the time of RA diagnosis for rapid radiographic progression (increase>5 units according to the Sharp score modified by van der Heijde after one year). The results from paper III indicated that baseline erosions, level of acute phase reactant and current smoking status were independent predictors for radiographic progression after 1 year. These results remained after further adjustment for treatment strategy. Three dimensional risk matrix including current smoking status, erosions and C-reactive protein showed a 12–63% risk gradient from patients carrying none compared with all predictors. Paper IV aimed to assess the utility of MSUS in patients with suspected inflammatory arthritis, using a probabilistic approach. In this study, the proportion of patients with maximal diagnostic certainty for inflammatory arthritis was increased significantly after performing MSUS. The similar significant increase was also observed for diagnostic certainty of RA. The findings from MSUS agreed with the final diagnosis in more than 95% of patients.