Background/Purpose: Systemic sclerosis (SSc) is a multisystem fibrosing autoimmune disease with a high mortality rate. Ethnicity can influence prevalence and disease characteristics in SSc. Less is known about SSc-associated interstitial lung disease (SSc-ILD), an important subgroup with even higher mortality rate. We investigate whether there are ethnic variations in people with SSc-ILD.

Methods: We conducted a retrospective cohort study of the Toronto Scleroderma Program – a network of academic and community clinics (1970-2023). Ethnicity was self-reported and categorized as Caucasian, Black, East-Asian, South Asian, or First Nations. We evaluated differences in demographics, disease manifestations, comorbidities, and survival in people with SSc-ILD. Kaplan-Meier survival curves were used to determine median survival and survival at 1-5, 10, 15, and 20 years. A Cox proportional hazards model estimated survival, adjusting for age, age of diagnosis, disease duration, and comorbidities.

Results: 405 people with SSc-ILD were included with n=234 (58%) Caucasian, n=57 (14%) South-Asian, n=49 (12%) East-Asian, n=28 (7%) Black, n=16 (4%) First Nation and n=22 (5%) Other. The median age at SSc diagnosis was significantly younger for First Nations ethnicity compared to Caucasian (38.4 years versus 52.0 years, p< 0.01). More Caucasians, South-Asians, and East-Asians had limited disease (53.2%, 51.8%, 53.1%), while more Black and First Nation had diffuse disease (57.1%, 62.5% respectively). Esophageal dysmotility was more common in Black and First Nations (96.4%, 93.8% respectively) than Caucasians, South Asians, and East Asians (88.5%, 80.7%, 71.4% respectively, p=0.01). Coronary artery disease occurred more frequently in First Nations (18.8%) than Caucasians, South Asians and East Asians (11.5%, 3.5%, 6.1%, p=0.04). East Asians had significantly better 10-year survival 93.2% (95%CI 85%, 100%) than Caucasians 78.3% (95%CI 72.1%, 85.1%). People of First Nations ethnicity appeared to have worse 10-year survival of 65.9% (95%CI 42.9%, 100%) but this was not statistically significant. In the adjusted survival analysis, age at diagnosis (p< 0.001) was an independent risk factor mortality, whereas ethnicity was not associated with mortality.

Conclusion: Ethnic variations in demographics, disease manifestations and comorbidities exist in SSc-ILD yet this does not result in significant differences in survival across ethnicities.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ethnic-variations-in-systemic-sclerosis-associated-interstitial-lung-disease/