Ethnic Variations in Systemic Sclerosis Disease Manifestations, Internal Organ Involvement, and Mortality.

Objective: A multiethnic systemic sclerosis (SSc) cohort study to evaluate ethnic variations in disease manifestations, internal organ involvement, and survival.

Methods: Adults who fulfilled the American College of Rheumatology/European League Against Rheumatism classification criteria for SSc between 1970 and 2017 were included. Self-reported ethnicity was categorized as European-descent white, Afro-Caribbean, Hispanic, Arab, East Asian, South Asian, First Nations, or Persian. The primary outcome was the time from diagnosis to death from all causes. Survival probabilities and median survival times were determined using Kaplan-Meier survival curves.

Results: There were 1005 subjects evaluated, the majority of whom were European-descent white (n = 745, 74%), Afro-Caribbean (n = 58, 6%), South Asian (n = 70, 7%), and East Asian (n = 80, 8%). Compared to European-descent white subjects, East Asians less frequently had calcinosis (29% vs 9%, p = 0.002) and esophageal dysmotility (88% vs 69%, p = 0.002); Afro-Caribbeans more frequently had interstitial lung disease (31% vs 53%, p = 0.007); and First Nations subjects more frequently had diffuse cutaneous disease (35% vs 56%, p = 0.02) and diabetes (5% vs 33%, p = 0.03). We found no difference in the short-term survival across ethnicities. Hispanic subjects have better longterm survival (81.3%, 95% CI 63-100) compared to European-descent white subjects (55%, 95% CI 51-60). East Asians appear to have the longest median survival time (43.3 yrs) and Arabs the shortest median survival time (15 yrs). There was no significant difference in median survival times between Afro-Caribbean and European-descent white subjects (22.2 vs 22.6 yrs).

Conclusion: Ethnic variations in some SSc disease manifestations are observed. However, this does not result in significant differences in short-term survival but may affect longterm survival.