Reduced Skeletal Muscle Independently Predicts One-Year Aggravated Joint Destruction In Patients With Rheumatoid Arthritis

Background: Numerous cross-sectional studies have reported the associations between rheumatoid arthritis (RA) and reduced skeletal muscle. We firstly explored the dynamic change of skeletal muscle and its effect on RA clinical outcomes in a real-world prospective cohort. Methods: Consecutive RA patients were treated according to the treat-to-target strategy and completed at least one-year follow-up. Clinical data and muscle index (assessed by bioelectric impedance analysis) were collected at baseline and visits at 3, 6, 9 and 12 months. Myopenia was defined by appendicular skeletal muscle mass index ≤7.0kg/m2 in men and ≤5.7kg/m2 in women. One-year radiographic progression as primary outcome was defined by a change in the total Sharp/van der Heijde modified score ≥0.5 units. Results: Among 348 recruited patients, 315 RA patients (mean age 47.9 years, 84.4% female) completed one-year follow-up. There were 143 (45.4%) RA patients showing myopenia at baseline. Compared with those without baseline myopenia, RA patients with baseline myopenia had higher rate of one-year radiographic progression (43.4% vs. 21.5%, all P<0.05). Baseline myopenia was an independent risk factor for one-year radiographic progression (AOR=2.360, 95%CI: 1.076-5.179), especially among RA patients in remission at baseline (AOR=3.492, 95%CI: 1.257-9.699). Further analysis of six subtypes of dynamic skeletal muscle change showed that newly acquired myopenia at endpoint was associated with radiographic progression (AOR=5.377, 95%CI: 1.599-18.080). Conclusions: Reduced skeletal muscle is an independent predicting factor for one-year aggravated joint destruction in both active and remission RA. The importance of dynamic monitoring of skeletal muscle and muscle improvement therapy are worth exploration. Funding Statement: This work was supported by National Natural Science Foundation of China (grant no. 81971527 and 81801606), Guangdong Natural Science Foundation (grant no. 2019A1515011928 and 2018A030313541), and Science and Technology Program of Guangzhou (grant No. 201904010088). Declaration of Interests: Jian-Zi Lin, Yin Liu, Jian-Da Ma, Ying-Qian Mo, Chu-Tao Chen, Le-Feng Chen, Qian-Hua Li, Ze-Hong Yang, Dong-Hui Zheng, Li Ling, Pierre Miossec, Lie Dai declare that they have no competing interests. Ethics Approval Statement: This study was conducted in compliance with the Helsinki Declaration and the protocol was approved by the Medical Ethics Committee of Sun Yat-sen Memorial Hospital (SYSEC-2009-06 and SYSEC-KY-KS-012). All participants gave their written informed consent before clinical data collection.