Evaluation of prevalence and causes of presarcopenia and sarcopenia in patients with scleroderma

The first aim of the study was to investigate the frequency of decreased muscle mass (sarcopenia or presarcopenia) in patients with systemic sclerosis (SSc, scleroderma) and its relationship with clinical features. The second objective was to reveal the role of ultrasonography (USG) in determining reduced muscle mass in SSc patients. Demographic and clinical data of 93 (86 female, 7 male) SSc patients were recorded. Appendicular skeletal muscle mass index (ASMI) and skeletal muscle mass index (SMI) were evaluated by bioelectric impedance analysis (BIA). The thicknesses of rectus abdominis, external oblique, internal oblique, transverse abdominis, rectus femoris and gastrocnemius muscles were measured by USG imaging. Muscle strength was measured with hand grip dynamometer. The frequency of decreased muscle mass was 13.9% according to ASMI and 9.6% according to SMI. Malnutrition and diffuse skin involvement were more frequent in patients with decreased muscle mass. In this group, the incidence of digital ulcers and the duration of the disease were also found to be increased however, a significant difference was observed only for the classification according to the SMI. There was no difference between groups regarding age, sex, organ involvement, current treatments, comorbidities, severity of gastrointestinal involvement and physical activity. Patients with decreased muscle mass had lower hand grip strength, however the correlation between muscle mass and hand grip strength was low-to-moderate. In patients with decreased muscle mass, the thickness of the gastrocnemius and rectus abdominis muscles were lower. Gastrocnemius thickness showed the highest correlation with ASMI and SMI. The cut off values for gastrocnemius thickness suggested by ROC analysis had a sensitivity of 92.3% and 100.0% and a negative predictive value of 97.9% and 100.0%, respectively. Intra and inter-observer agreement was very high for ultrasonographic measurements. In conclusion, decrease in muscle mass is not infrequent in patients with SSc. Patients with malnutrition and diffuse skin involvement are particularly at increased risk for this condition. Gastrocnemius thickness measurement with USG imaging may be used as a screening test due to its high sensitivity and negative predictive value in detecting the decrease in muscle mass in SSc patients. Key words:Systemic sclerosis, muscle mass, bioelectric impedance analysis, ultrasonography