Prevalence and Clinical Characteristics of Systemic Sclerosis in Alaska Native and American Indian Peoples in Alaska.

OBJECTIVE: Systemic sclerosis (SSc) is known to exhibit significant epidemiologic and clinical variation. This study aimed to describe the clinical and epidemiologic characteristics of SSc in Alaska Native and American Indian (AN/AI) individuals in Alaska. METHODS: Adults with a potential diagnosis of SSc were identified through an electronic health record query for SSc-related codes from 2012 to 2019 in the participating tribal health organizations in the Alaska Tribal Health System (ATHS). Detailed medical record abstraction was performed to confirm diagnoses and clinical characteristics, including demographics, SSc subtype, organ involvement, serologic test results, and medications. The denominator for prevalence was the 2019 ATHS user population aged ≥18 years. RESULTS: The age-adjusted prevalence of SSc was 354 (95% confidence interval [CI] 241-504) per 1,000,000 adults overall, 503 (95% CI 323-752) per 1,000,000 in women, and 188 (95% CI 82-379) per 1,000,000 in men. Of the 36 adults identified with SSc, the mean age at diagnosis was 59.9 years (median 62 years), with a female predominance (28 [77.8%]; female-to-male ratio 3.5:1). Diffuse SSc prevalence was 95 (95% CI 44-184), and limited SSc prevalence was 258 (95% CI 164-391) per 1,000,000. Although most clinical features appear to be similar to other populations, a high prevalence of pulmonary arterial hypertension, gastrointestinal manifestations, and telangiectasias were notable. CONCLUSION: This is the first study to describe the epidemiology and clinical characteristics of SSc in AN/AI individuals in Alaska. The prevalence, average age at onset, female predominance, and most clinical features are generally similar to those in studies of SSc in other populations.