What have multicentre registries across the world taught us about the disease features of systemic sclerosis?

Introduction The aim of this study is to compare the clinical features, mortality and causes of death of systemic sclerosis (SSc) patients in four large multicentre registries. Methods Patients seen at least once in the Australian Scleroderma Cohort Study (ASCS) (n = 1714), the Canadian Scleroderma Research Group (CSRG) (n = 1628), the European League Against Rheumatism Scleroderma Trials and Research (EUSTAR) Network (n = 13,996) and the Systemic Sclerosis Cohort in Singapore (SCORE) (n = 500) before August 2016 were included. Clinical manifestations and survival in cohorts and disease subtypes were compared. Results Among 17,838 SSc patients, most were female (86.1%), Caucasian (84.6%) and had the limited cutaneous subtype (lcSSc) (65.0%). The anti-centromere autoantibody was the most prevalent (37.6%). More patients in SCORE had the diffuse subtype (dcSSc) (49.3%) and Scl-70 autoantibody (38.8%) (p<0.001). Patients with dcSSc were more likely to be younger and male (p<0.001) and have shorter disease duration, more calcinosis, tendon friction rubs and synovitis (all p<0.001). Interstitial lung disease (ILD) occurred more frequently in dcSSc but prevalence of pulmonary arterial hypertension (PAH) was similar in both subtypes. More deaths occurred among SCORE patients who had the shortest median survival (p<0.001). The survival of patients with early disease, males and those with dcSSc was shorter than that of patients with prevalent disease, female gender and lcSSc, respectively. SSc-related complications accounted for more than 50% of deaths, with PAH and ILD being the most common. Conclusions This meta-cohort of SSc patients, the largest reported to date, provides insights into the impact of race and sex on disease manifestations and survival and confirms the early mortality in this disease.