Native American patients with systemic lupus erythematosus (SLE) have earlier disease onset, higher rates of autoantibodies, and a different clinical pattern of disease than Americans of European ancestry, researchers reported.
The average age at onset of disease among Native Americans was 29.9, compared with 32.0 for Americans of European ancestry (P=0.0157), according to Judith A. James, MD, PhD, of the Oklahoma Medical Research Foundation in Oklahoma City, and colleagues.
Action Points
- Native American patients with systemic lupus erythematosus have somewhat earlier onset of disease, higher rates of autoantibodies, and a different clinical pattern of disease than Americans of European ancestry, according to ethnically diverse registry data.
- Be aware, also, that Native Americans often face significant barriers to care, including lack of insurance and residence in remote areas, leading to less effective treatment and worse outcomes.
In addition, the rate of antinuclear autoantibody positivity was 97% among Native Americans compared with 91% among European Americans (P=0.0004), the team reported in
"SLE disproportionately affects certain minority and socially marginalized populations with a higher degree of morbidity, earlier mortality, and enhanced comorbidities."
Moreover, Native Americans often face significant barriers to care, including lack of insurance and residence in remote areas, leading to less effective treatment and worse outcomes. have shown that the incidence and prevalence of SLE is similar among Native Americans and African Americans, but higher than among European Americans.
In an attempt to quantify this excess disease burden for SLE among Native Americans, James et al analyzed data from the Lupus Family Registry and Repository, an ethnically diverse cohort of more than 3,000 patients.
The overall group consisted of 1,567 patients of European ancestry, 1,074 African Americans, 268 Native Americans, and 239 Hispanics. All were residents of the continental United States and Puerto Rico (71%), Latin America (27%), Canada (0.3%), and unspecified (2%).
The age at disease onset of Native Americans was similar to that seen for African Americans (30.8 years) and Hispanics (27.8). Moreover, a "striking" percentage of Native Americans -- 26% -- were diagnosed during the first 2 decades of life, compared with 19% of African Americans (P=0.005) and 21% of European Americans.
The pattern of autoantibodies also differed among the groups: Anti-ds-DNA antibodies were present in 34% of Native Americans and 32% of African Americans, but in only 22% of European Americans (P<0.0001) and 23% of Hispanics (P=0.0076). The Native Americans also had higher rates than European Americans of anti-Ro/SSA antibodies and anticardiolipin IgG.
Clinical differences included a higher rate of malar rash (59% versus 45%, P=0.0001); photosensitivity (54% versus 38%, P<0.0001); and oral ulcers (44% versus 36%, P=0.0293) among Native Americans than among African Americans. Compared with European Americans, Native Americans also had higher rates of proteinuria (46% versus 35%, P=0.001) and hemolytic anemia (20% versus 10%, P<0.0001).
Disparities also were present with regard to concurrent autoimmune diseases. For instance, Native Americans had higher rates than African Americans of Raynaud's syndrome (34% versus 27%, P=0.0186), as well as Sjogren's syndrome, interstitial lung disease, and systemic sclerosis. However, myalgias were less common among Native Americans than among African Americans, Hispanics, or European Americans.
Notable differences were observed for treatment. "Hydroxychloroquine, an antimalarial drug, remains the cornerstone of SLE treatment and is recommended for all patients with SLE without a contraindication," the researchers wrote. Yet only 68% of Native American patients received hydroxychloroquine, compared with 74% of African Americans (P=0.0308); 77% of Hispanics (P=0.0173); and 79% of European Americans (P=0.0001).
However, area of residence was an important factor with regard to hydroxychloroquine use. Among Native Americans living in the U.S. and Puerto Rico, 82% received this treatment, compared with only 32% of those living in Latin America.
Native Americans more often were treated with methotrexate and azathioprine, while mycophenolate mofetil (CellCept) was more commonly used by both Native Americans and African Americans.
The reasons for the differences in medication use were unclear, but may relate to concerns about retinopathy with hydroxychloroquine exposure or regional differences in treatment approaches, the researchers speculated.
"For many Native Americans, early diagnosis with continued monitoring is difficult to obtain due to confusing autoantibody results and restricted access to healthcare specialists. These disparities thus potentially contribute to delays in diagnosis and clinical monitoring, potentially resulting in increased damage accrual and worse outcomes."
The team added that research will be needed to identify potential molecular and genetic markers of SLE that might enable earlier and more specific diagnosis among Native Americans.
Disclosures
The study was funded by the National Institutes of Health, the Indian Health Service, and the U.S. Department of Veterans Affairs.
One co-author reported financial support from ThermoFisher.
Primary Source
Lupus: Science & Medicine
Kheir J, et al "Unique clinical characteristics, autoantibodies and medication use in Native American patients with systemic lupus erythematosus" Lupus Sci Med 2018; DOI:10.1136/lupus-2017-000247.