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

Abstract

The objective is to describe and compare demographic, clinical, and serological characteristics of patients with systemic sclerosis (SSc) according to ethnic background. 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. 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%). 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.