ASSOCIATION BETWEEN OVERWEIGHT/OBESITY AND DISEASE ACTIVITY ON BONE SCINTIGRAPHY IN PATIENTS WITH RHEUMATOID ARTHRITIS

Background: In previous studies, obesity is highly prevalent in patients diagnosed with rheumatoid arthritis and it is positively associated with disease activity . Although Tc-99m-labeled bone scintigraphy has been widely performed to evaluate the disease activity of the joints involved in this disease ; the effect of body mass index (BMI) on the results of bone scintigraphy is yet to be accessed. Objectives: In the present study, we evaluated the relationship between BMI and uptake intensity of the joints that was measured using bone scintigraphy in patients with rheumatoid arthritis. Methods: A total of 80 patients (21 men and 59 women; mean age 56±14 years) with rheumatoid arthritis who underwent Tc-99m methylene diphosphonate bone scintigraphy before treatment were enrolled in this study. Data were collected for baseline BMI and disease activity score for the 28 joints using erythrocyte sedimentation rate (DAS28-ESR) of these patients. Uptake intensity of these 28 joints was automatically measured for each patient using an in-house software, expressed as joint uptake-to-background normal bone uptake ratio (joint uptake ratio). The correlation of BMI with DAS28-ESR and joint uptake ratio on bone scintigraphy was assessed. Results: Mean BMI of the enrolled patients was 24.4±3.7 kg/m and 50 patients (62.5%) were classified as overweight/obesity. BMI was significantly positively correlated with the sum of 28 joint uptake ratios on bone scintigraphy (p=0.021, correlation coefficient=0.358) as well as DAS28-ESR (p=0.030). Patients with overweight/obesity (39.2±9.5) had significantly higher values of the sum of 28 joint uptake ratios than the other patients (33.9±9.5; p=0.025). In correlation analysis with each joint uptake ratio of 28 joints, BMI more significantly positively correlated with uptake ratios of shoulder, elbow, and knee joints than those in wrist and hand joints. In subgroup analysis of patients having low (DAS28-ESR ≤3.2) and high (DAS28-ESR >3.2) disease activity, BMI still showed significant positive correlation with the sum of 28 joint uptake ratio on bone scintigraphy in both subgroups (p<0.05 for all). Conclusion: The Baseline BMI in patients with rheumatoid arthritis had significant positive correlation with joint uptake intensity measured on bone scintigraphy, especially for large joints. The results of our study might provide an evidence that supports an association between BMI and disease activity of rheumatoid arthritis. REFERENCES: [1]de Resende Guimaraes MFB, Rodrigues CEM, Gomes KWP, et al. High prevalence of obesity in rheumatoid arthritis: association with disease activity, hypertension, dyslipidemia and diabetes, a multi-center study. Adv Rheumatol 2019;59:44. [2]Kim JY, Choi YY, Kim CW, et al. Bone scintigraphy in the diagnosis of rheumatoid arthritis: is there additional value of bone scintigraphy with blood pool phase over conventional bone scintigraphy? J Korean Med Sci 2016;31:502-9. Acknowledgments: Research relating to this abstract was funded by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Ministry of Science and ICT) (grant number: NRF-2018R1C1B5040061). Disclosure of Interests: None declared Citation: Ann Rheum Dis, volume 79, supplement 1, year 2020, page 503Session: Diagnostics and imaging procedures (Poster Presentations)