Background The assessments of joint damage in patients with rheumatoid arthritis (RA) are mainly restricted to small joints in the hands and feet. However, the development of arthritis in RA patients often involves the large joints, such as the shoulder, elbow, hip, knee and ankle.
Few previous reports have studied the predictive value of radiographic findings for destruction of the large joints in RA patients.
18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) precisely visualizes the disease activity in large joints affected by RA. Furthermore, the response on FDG-PET correlates with the clinical response to biologic treatment. However, it is not thoroughly understood whether FDG-PET/CT findings correlate with the severity of destruction in the large joints of the RA patients.
Objectives To investigate the associations between destruction of the large joints and FDG-PET/CT findings, the disease activity and laboratory parameters after the administration of biological therapy in patients with RA.
Methods 23 RA patients (six males and 17 females; mean age of 66.9±7.9 years) were assessed in this study. FDG-PET/CT was performed before the initiation of biological therapy and six months after the therapy. The extent of FDG uptake in large joints (shoulder, elbow, hand, hip, knee and ankle) was analyzed using the maximum standardized uptake value (SUVmax). Radiographs of the 12 large joints per patient, for a total of 276 joints, were obtained at baseline and after two years. Twelve joints had previously been treated with joint replacement surgery at baseline and were excluded from this analysis. A total of 264 large joints were assessed according to Larsen's method. The disease activity and laboratory parameters were evaluated at baseline and six, 12 and 24 months after the therapy. A logistic regression analysis was performed to determine the factors most significantly contributing to the progression of joint destruction within two years.
Results Among the 264 joints, radiographic progression of joint destruction was detected in 33 joints. The SUVmax at baseline and six months and the disease activity score (DAS) 28 – erythrocyte sedimentation rate (ESR) at six, 12 and 24 months were significantly higher in the group with progressive joint destruction. The multivariate logistic regression analysis revealed the SUVmax at baseline and DAS28-ESR at six months were found to be factors associated with joint destruction at two years (p<0.05).
Conclusions The FDG uptake was significantly higher in the large joints demonstrating radiographic progression of destruction at two years after the initiation of biological therapy. The SUV max at baseline and the DAS28–ESR at six months after the biological treatment were identified to be significant factors predicting destruction of the large joints at two years.
Disclosure of Interest None declared