Distinct Systemic Sclerosis Phenotypes Related to Ethnicity: An Opportunity to Personalize Care?

OBJECTIVE: The objective is to describe and compare demographic, clinical, and serological characteristics of patients with systemic sclerosis (SSc) according to ethnic background. METHODS: Participants enrolled in the Canadian Scleroderma Research Group cohort who self-identified to a single ethnicity group were included. Baseline characteristics were compared using analysis of variance, chi-square, or Kruskal-Wallis rank sum test. Kaplan-Meier curves and Cox regression were used to estimate mortality. RESULTS: Of 1,477 eligible participants, 1,345 (91.1%) identified as White, 55 (3.7%) as Indigenous, 22 (1.5%) as East/Southeast Asian, 20 (1.4%) as Middle Eastern, 16 (1.1%) as Black, 12 (0.8%) as South Asian, and 7 (0.5%) as Latin American. White individuals had a lower prevalence of diffuse cutaneous SSc (33% vs 53%) and telangiectasias (44% vs 67%) compared with other ethnicities. Conversely, Black individuals had a higher prevalence of myositis (44% vs 10%), higher mean modified Rodnan skin score (18.4 vs 9.6), lower mean forced vital capacity (73.7% predicted vs 92.9% predicted) and DLco values (54.5% predicted vs 70.6% predicted), and the lowest survival probabilities at one (85%) and five years (57%). Indigenous individuals had the highest prevalence of anti-RNA polymerase III antibodies (34% vs 19%) and were more frequently affected by lower gastrointestinal manifestations. East/Southeast Asian individuals were the least frequently affected by Raynaud phenomenon (90%) and digital ulcers (29%). CONCLUSION: Ethnicity was associated with distinct SSc phenotypes. These differences provide prognostic information that can guide screening and management strategies, thus representing an opportunity to personalize care.