Ab0799 association between muscle quality and mortality in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis

Background Decreased muscle mass is frequently observed in patients with autoimmune rheumatic diseases; however, the relationship between muscle quality and patient outcomes has not been well understood. Objectives This study evaluated the influence of muscle quality on the outcomes of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Methods Records of patients with AAV (microscopic polyangiitis, granulomatosis with polyangiitis, and eosinophilic granulomatosis with polyangiitis) at the Severance Hospital having computed tomography (CT) images at disease diagnosis were retrospectively reviewed. For muscle quality measures, normal attenuation muscle area (NAMA), low attenuation muscle area (LAMA), total abdominal muscle area (TAMA), and intramuscular adipose tissue (IMAT) in the axial muscles of the middle third lumbar vertebra level was calculated. Correlations between NAMA, LAMA, and IMAT and patient characteristics and outcomes were assessed. Results A total of 136 patients with CT images at AAV diagnosis were identified. Correlation analyses revealed that age, female sex, total cholesterol, and alanine aminotransferase were significantly associated with NAMA. LAMA was associated with age, body mass index (BMI), five-factor score (FFS), and C-reactive protein, while a relationship between IMAT and age and BMI was observed. Cox-proportional hazard analysis demonstrated that NAMA/TAMA≤0.46 (odds ratio [OR] 5.612, 95% confidence interval [CI] 1.758-17.909, p=0.004), female sex (OR 0.228, 95% CI 0.075, 0.684, p=0.008), dyslipidemia (OR 3.819, 95% CI 1.380, 10.571, p=0.010), and FFS (OR 2.160, 1.298-3.595, p=0.003), were independent factors associated with mortality. Conclusion Higher mortality was observed in patients with AAV with NAMA/TAMA ≤ 0.46, indicating that cautious monitoring is required in these patients. References [1]An HJ, Tizaoui K, Terrazzino S et al (2020) Sarcopenia in Autoimmune and Rheumatic Diseases: A Comprehensive Review. Int J Mol Sci 2020;21. https://doi.org/10.3390/ijms21165678 [2]Lee MJ, Kim HK, Kim EH, Bae SJ, Kim KW, Kim MJ, Choe J (2021) Association Between Muscle Quality Measured by Abdominal Computed Tomography and Subclinical Coronary Atherosclerosis. Arterioscler Thromb Vasc Biol 2021;41:e128-e140. https://doi.org/10.1161/atvbaha.120.315054 Figure : Kaplan Meier-analysis with clinical outcomes according to NAMA/TAMA cut-off value of 0.46. Acknowledgements: NIL. Disclosure of Interests None Declared.