A new study in Arthritis Care & Research highlights potential differences in incidence, the presentation of prominent symptoms and laboratory findings in African Americans and Native Americans with Sjögren’s syndrome compared with white populations. Native Americans appear to be at higher risk of the disease, although they often display fewer of the classic symptoms. Importantly, findings suggest that African Americans may have a higher risk of lymphoma related to Sjögren’s syndrome.1
Study Impetus & Design
Astrid Rasmussen, MD, PhD, is a research associate member in the Arthritis and Clinical Immunology and the Genes and Human Disease Research Programs of the Oklahoma Medical Research Foundation, Oklahoma City. In collaboration with her colleagues, she was the senior author of “Sjögren’s in Minority Populations of the USA.”
Earlier work has demonstrated race-specific variations in incidence, disease manifestations and prognosis in minority populations in other rheumatic diseases. Dr. Rasmussen notes, “In lupus, we know that people of African American ancestry have more aggressive disease, worse prognosis and a higher rate of disease. And we already knew that Native Americans tend to have more rheumatoid arthritis.”
Only fairly recently have researchers begun to address key questions about epidemiology and racial variations in Sjögren’s syndrome. Dr. Rasmussen points out that previous epidemiological studies have primarily analyzed white populations. “There was very little knowledge about whether racial disparities we see in these other diseases would also hold true in Sjögren’s,” she says.
Dr. Rasmussen and her colleagues realized they could tackle an important aspect of this question themselves. “We have one of the largest cohorts of Sjögren’s syndrome patients in the country, and we’re in Oklahoma, which has a large Native American population,” she says.
The researchers analyzed data from 1,682 people in a cross-sectional cohort evaluated for sicca symptoms. The large majority of these patients were assessed at the Oklahoma Medical Research Foundation. Patients were recruited for a one-time visit for a multi-specialty clinical evaluation for Sjögren’s syndrome using criteria from the American-European Census Group (AECG) and the 2016 criteria created by the ACR and the European League Against Rheumatism (EULAR).2,3
In addition to a full examination, the evaluation included measurement of whole, unstimulated salivary flow; a salivary gland biopsy; Schirmer’s I testing; ocular staining scores; and testing for relevant autoantibodies, such as anti-SSA/Ro (anti-Sjögren’s syndrome antigen A) and anti-SSB/La (anti-Sjögren’s syndrome antigen B).
Ultimately, 648 patients met the classification criteria for Sjögren’s syndrome. “They had the dry eyes, the dry mouth of sicca, but they also had evidence of objective autoimmune disease, such as autoantibodies or infiltration of the salivary gland with lymphocytes,” Dr. Rasmussen says.
