Pos1323 body composition in patients with systemic sclerosis: results of a computed tomography study

Background Subclinical primary muscular involvement and malnutrition may occur in a significant percentage of patients with systemic sclerosis (SSc), and they are potential risk factors for the development of sarcopenia [1]. Sarcopenia is defined as age-associated loss of muscle mass, strength, and function, and unlike other chronic rheumatic inflammatory disorders, it has been poorly investigated in SSc patients. In recent years, some imaging methods have emerged for the identification of sarcopenic markers such as altered muscle composition and fat infiltration (myosteatosis). Objectives To evaluate the occurrence of myosteatosis and the prognostic role of body composition, assessed by computed tomography, in patients affected with SSc. Methods Patients affected with SSc (2013 EULAR/ACR criteria) referring to our tertiary center from 2015 to 2021 who underwent chest computed tomography to assess pulmonary involvement were included. A semi-automatic segmentation of the subcutaneous fat and paravertebral muscle was performed at the level of the 12 th dorsal vertebra using a software and the following body composition variables (BCV) were collected: subcutaneous fat area, subcutaneous fat Hu, paravertebral muscle area, paravertebral muscle Hu. Myosteatosis was considered as Hu values <30. The Student’s t-test was used to evaluate if any difference regarding BCV occurred between males and females. Logistic regression analysis was applied to assess the role of the BCV on the overall survival while the Spearman correlation coefficient was used to evaluate the relationship between the BCV and the skin score. For all the analyses the applied significance level was p<0.05. Results Sixty SSc patients were included (51 females; mean age 55.63±14 years). Most patients were positive for anti-nuclear antibodies (ANA, 90%), with anti-topoisomerase I specificity in 61.6% of them; twenty-nine patients (48.3%) were affected by the diffuse cutaneous form. At baseline, the mean modified Rodnan skin score (mRSS) was 10.22 (±8.8) and the mean revised EUSTAR activity index was 2.08 (±1.4). Signs of myosteatosis were detected in forty-seven (78.3%) SSc patients. Males showed significantly greater muscle areas (males 9732±3019 vs. females 6599±1328 mm 2 ; p<0.001) and less hypodense subcutaneous fat (males 76±18 vs. females 88±16 Hu; p=0.027). Overall, seven patients deceased at a 5-year follow-up. No correlation was found between BCV and the mRSS. None of the radiological variables emerged as a predictor of survival. Conclusion Most patients with SSc are affected by myosteatosis, even those without symptoms of muscle involvement, while overall body composition does not appear to predict survival. The results of our pilot study may open the door to evaluating the role of body composition in SSc patients: larger longitudinal studies looking at different time-points in the disease course may provide further insights. Reference [1]Paik JJ, Mammen AL, Wigley FM, Gelber AC. Myopathy in scleroderma, its identification, prevalence, and treatment: lessons learned from cohort studies. Curr Opin Rheumatol 2014; 26:124–30. Acknowledgements: NIL. Disclosure of Interests None Declared.