Alaska Native Tribal Health Consortium Anchorage, AK, United States
Vivek Mehta and Elizabeth Ferucci, Alaska Native Tribal Health Consortium, Anchorage, AK
Background/Purpose: Systemic sclerosis (SSc) is known to have more severe manifestations and higher mortality in Black populations, while fewer studies have examined disparities in epidemiology or clinical features in other populations. Indigenous North American (INA) populations have higher prevalence and severity of a number of autoimmune disorders, but no recent studies have examined the clinical characteristics of SSc in INA populations. We sought to describe the clinical characteristics of SSc in the Alaska Native/American Indian (AN/AI) population in Alaska.
Methods: This study was approved by the Alaska Area IRB as expedited research with a waiver of consent. Tribal approval was obtained from participating regional tribal health organizations. Potential cases were identified by a query of administrative data from the electronic health records for International Classification of Disease (ICD)-9 and ICD-10 codes possibly identifying SSc during the period from 2012-2019. A detailed medical record abstraction was performed for each potential case, including verification of diagnosis and clinical features. Cases were required to have a diagnosis confirmed by a rheumatologist in the medical record. Clinical characteristics are reported as documented in the medical record, including demographics, SSc subtype, organ involvement, serologies, and medications ever prescribed for SSc.
Results: A total of 36 confirmed cases of SSc were identified. Of these, 27 (75%) had limited cutaneous systemic sclerosis and 9 (25%) had diffuse cutaneous systemic sclerosis. The mean age at SSc diagnosis was 52.7 years (standard deviation 14.0). SSc was more common in women (n=28, 77.8%) compared to men (n=8, 22.2%). Skin thickening (n=33, 91.7%), Raynaud's (n=31, 86.1%), telangiectasia (n=25, 69.4%), and calcinosis (n=15, 41.6%) were some of the common clinical features. Digital ulcers were noted to be frequent (n=16, 44.4%), and 7 patients had experienced digital amputation. Pulmonary hypertension was diagnosed in 6 (16.7%) patients and interstitial lung disease was diagnosed in 13 (36.1%) patients. Gastrointestinal (GI) manifestations were common (n=33, 91.7%), with gastroesophageal reflux disease (n=28) and esophageal dysmotility (n=20) being the most common GI diagnosis. Heart and kidney involvement were uncommon. Most patients were positive for Antinuclear antibody (n=32, 88.9%). Of specific antibodies, centromere antibody was most common (n=15), followed by Scl-70 antibody (n=6), then RNP antibody (n=5). Hydroxychloroquine (n=16) was the disease-modifying anti-rheumatic drug (DMARD) most commonly ever prescribed, followed by mycophenolate mofetil (n=9), then cyclophosphamide (n=6). Fewer than five patients had ever received rituximab or methotrexate.
Conclusion: This is first study to describe clinical characteristics of SSc in AN/AI people in Alaska. Raynaud's, telangiectasias, calcinosis, pulmonary and GI manifestations were common. Heart and kidney involvement was uncommon. The proportion of patients with limited vs. diffuse SSc, female gender, and specific organ manifestations appears similar to those described in other populations.
