Background Systemic sclerosis (SSc) is a connective tissue disease characterized by skin and internal organ fibrosis due to immune activation, vascular damage and excessive synthesis of collagen . Muscle involvement is still a variable feature, with prevalence from 14% to 79% due to the lack of diagnostic consensus criteria .
Objectives The aim of this study was to characterize the clinical, biochemical and immunological features of SSc patients with muscle involvement and to find any correlations amongst them.
Methods We retrospectively analysed data for 18 SSc patients with myopathy out of 254 SSc patients followed between 2000 and 2016 in a Romanian academic hospital centre. All patients fulfilled the ACR/EULAR criteria for the diagnosis of SSc and had a history of myopathy. Myopathy was defined as the presence of muscle weakness, myalgia, with creatine kinase (CK) and/or lactate dehydrogenase (LDH) level >2N (two times the upper normal range). Clinical, biochemical and immunological parameters were assessed by descriptive statistics, logistic regression and Chi-square test.
Results The prevalence of myopathy was 7.0%. General features in myopathy-SSc patients are detailed in Table 1. Male sex represents a risk factor for muscle involvement (OR=38.2, p-value<0.001). The ratio of diffuse subtype to the limited subtype was 0.8. The major organ involvement associated with myopathy was lung fibrosis (55.5%). Most prevalent autoantibody was anti-Scl70 (44.4%). The onset of muscle symptoms occurred within a median of 1.6 years (range 0–12 years) after SSc diagnosis. Among the studied patients, 12 (66.6%) had muscle weakness, and 13 (72.2%) had myalgia. CK and LDH levels were elevated in 16 (88.88%) and 18 (100%) cases, respectively. AST level values were found to be slightly higher than ALT ones but not statistically significant (p-value=0.15). A positive correlation was found between levels of LDH and AST (Pearson coefficient=0.72) and between CK and LDH (Pearson coefficient=0.66). No association was identified with inflammatory parameters.
Conclusions This study emphasizes the fact that male SSc patients are at increased risk of developing myopathy. Although the prevalence of muscle involvement was quite low than reported in other cohort series, the results are similar to the more recent publications . We showed that myopathy occurred more often in anti-Scl70 positive patients and that anti-centromere wasn't present at all. All patients should be carefully assessed for muscle involvement in the first years of SSc diagnosis and screened for lung fibrosis, regardless of cutaneous subtype of the disease.
Systemic sclerosis: current pathogenetic concepts and future prospects for targeted therapy. Lancet 1996; 347:1453.
Paik, J., Mammen, A., Wigley, F. and Gelber A. Myopathy in scleroderma, its identification, prevalence, and treatment: lessons learned from cohort studies. Curr Opin Rheumatol 26: 124–130.
RaB Ranque, A Bérezné, V Le-Guern, C Pagnoux et al. Myopathies related to systemic sclerosis: a case–control study of associated clinical and immunological features. Scand J Rheumatol 2010;39:498–505.
Disclosure of Interest None declared