Assessment of sarcopenia in patients with Takayasu arteritis: A prospective cross‐sectional observational study

BACKGROUND: We aimed to evaluate muscle mass, muscle function, and sarcopenia prevalence in patients with Takayasu arteritis (TAK), and to explore associations with disease activity and vascular involvement. METHODS: A total of 103 TAK patients and 75 age- and sex-matched healthy controls (HC) were included. The muscle strength of the participants was assessed using handgrip and chair-stand tests, while muscle mass was evaluated through two separate measurement methods: bioelectrical impedance analysis (BIA) and ultrasonography (US). For US measurement, the quadriceps and the biceps muscle were measured. Prevalence of sarcopenia was defined using the updated European Working Group on Sarcopenia in Older People (EWGSOP2) and International Society of Physical and Rehabilitation Medicine (ISarcoPRM) algorithm. Probable, confirmed and severe sarcopenia were collectively categorized as sarcopenia. RESULTS: Sarcopenia prevalence was 29.1% in TAK and 12% in HC by ISarcoPRM (P < 0.001), and 59.2% versus 26.7% by EWGSOP2 (P < 0.001). Agreement between the EWGSOP2 and ISarcoPRM definitions for sarcopenia were poor (P = 0.062, ĸ = 0.153). No difference in BIA-based muscle mass was observed between the TAK and HC groups; however, quadriceps muscle thickness (MT) and Sarcopenia Thigh Adjusted Ratio (STAR) index were significantly lower in TAK (P < 0.001). CONCLUSION: This first study of sarcopenia in TAK shows that the prevalence of sarcopenia is higher in TAK compared with HC. US-based measurements were more sensitive than BIA, suggesting US may be a practical screening tool in TAK, detecting regional changes due to combined systemic inflammation and vasculitic arterial involvement.