LAUSR

Objectives: Systemic sclerosis is a severe and rare chronic auto-immune multisystem disorder characterized by vasculopathy and skin stiffness. Ethnic and geographical origin can influence the outcomes. In this study, we compared the phenotypic characteristics of Iranian and French patients. Methods: This cross-sectional study was performed on 200 Iranian and 268 French systemic sclerosis patients. Iranian patients collected from the Iranian systemic sclerosis cohort of the Rheumatology Research Center, Shariati hospital, Tehran University of Medical Sciences. The French population was monocentric, and it was constituted by the patients included locally in the EUSTAR database in December 2016. Results: The mean age at onset was significantly lower in Iranian patients (35.58 ± 11.68 vs 47.06 ± 13.54, p-value < 0.001). The female-to-male ratio was approximately 5.2:1 and was not different in the two populations. The prevalence of diffuse cutaneous systemic sclerosis was significantly higher in Iranian patients (60.2% vs 42.85%, p-value < 0.001). Calcinosis cutis and joint synovitis were more prevalent in French patients (p-value = 0.013, <0.001). The positivity of anti-topoisomerase antibody was higher in Iranian patients, whereas the anti-centromere antibody predominated in French cases (p-value < 0.001). Restrictive pattern of pulmonary function test was more common in Iranian patients (p-value < 0.001), while estimated pulmonary arterial pressure by echocardiography was higher in French patients (p-value < 0.001). Conclusion: It seems that systemic sclerosis occurred in younger ages among Iranian female with the predominance of diffuse cutaneous subtype. In addition, lung interstitial disease appeared to be more prevalent and severe in Iranians than French patients.