FRI0631 MUSCLE STIFFNESS AND WEAKNESS IN RHEUMATOID ARTHRITIS – A SHEAR WAVE ELASTOGRAPHY STUDY
Authors: Abdulrahman M. Alfuraih, Ai Lyn Tan, Philip O’connor, Paul Emery, Richard Wakefield
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Myopathy is a recognised but less investigated symptom of rheumatoid arthritis (RA) compared to other extra-articular manifestations. To date, the documentation of myopathic features in RA is poorly detailed. No studies have yet utilised a non-invasive quantitative method to define and investigate these features. Shear wave elastography (SWE), a novel ultrasound technology, can measure muscle stiffness to provide insight into the biomechanical properties of skeletal muscle. <h3>Objectives</h3> 1- To investigate muscle stiffness (using SWE) and strength in three cohorts of RA patients compared to healthy controls. 2- To study the association between muscle strength and stiffness in RA. <h3>Methods</h3> Shear wave velocity (SWV), as a measure of muscle stiffness, was evaluated in the quadriceps, hamstrings and biceps brachii in 80 RA patients from three disease activity groups newly diagnosed treatment naïve RA [n=29; mean age 56.8 ± 10.6 years], persistent active RA for at least 1 year [n=18; 60.9 ± 15.9 years] and remission RA for at least 1 year [n=33; 65.9 ± 11.6 years], and compared them to 40 healthy controls (56.8 ± 10.6 years). The participants performed various muscle tests (handgrip strength, expanded timed get up and walk test (ETGUG), chair stand and isokinetic knee extension/flexion) to assess their strength and physical performance. One-way ANOVA was used to compare SWV and muscle assessment results, and Pearson's correlation was used to evaluate the correlation between muscle stiffness and strength. <h3>Results</h3> Mean SWV was not significantly different amongst the RA groups or compared to the healthy controls (p&gt;0.05). For example, the rectus femoris SWV was 1.69±0.15 m/s for healthy controls, 1.68±0.18 m/s for new RA, 1.70±0.16 m/s for active RA and 1.68±0.14 m/s for remission RA (p=0.96). The muscle assessment results are presented in table 1 and compared to healthy controls in figure 1. Overall, the active and new RA groups showed significant muscle weakness compared to healthy controls. The remission RA group did not show a significant difference except in the isokinetic knee strength (-21%; p=0.027). The correlations between SWE and the muscle assessment results were weak and insignificant (r&lt;0.30; p&gt;0.05). <h3>Conclusion</h3> Muscle stiffness, as determined using SWE, does not appear to be altered or associated with muscle weakness in RA patients. The remission RA group showed significantly better strength and physical performance compared to new untreated or persistently active RA groups. Future research should investigate the significant muscle weakness in RA in addition to developing prevention and therapeutic strategies. <h3>Disclosure of Interests</h3> Abdulrahman M. Alfuraih: None declared, Ai Lyn Tan: None declared, Philip O'Connor: None declared, Paul Emery Grant/research support from: Pfizer, MSD, AbbVie, Bristol-Myers Squibb, Roche, Consultant for: Pfizer, MSD, AbbVie, Bristol-Myers Squibb, UCB, Roche, Novartis, Gilead,Samsung, Sandoz and Lilly, Richard Wakefield: None declared