according to findings from an analysis of single-center cohort data over a 10-year period.
Indeed, among patients in the cohort of 402 scleroderma patients at MedStar Georgetown University Hospital in Washington, lower household income was predictive of higher mortality during follow-up, independent of race, according to first author Duncan F. Moore, MD, and his colleagues at the hospital.
Previous studies have demonstrated increased risk for scleroderma in African American patients, who also are more likely than non–African Americans to be diagnosed at a younger age and to have conditions including more diffuse cutaneous disease, more severe restrictive lung disease, more cardiac and renal involvement, and increased mortality, the authors wrote in.
“We did clearly show that African Americans have worse outcomes and severe pulmonary involvement, but I was surprised that there still was a major contribution of socioeconomic status affecting outcomes for all patients, even though only 10% of our patients were indigent and on medical assistance,”, senior author of the study and professor of rheumatology at Georgetown University, said in an interview. “I still feel strongly that there are likely genetic issues as to why African Americans have such severe disease. We are eager to learn more from the [Genome Research in African American Scleroderma Patients] study, which is specifically looking at the genetic issues in African American scleroderma patients,” she said.
Of the 402 scleroderma patients at MedStar Georgetown who were seen during 2006-2016, 202 were African American. A total of 186 African American and 184 non–African American patients in the study met the 2013 American College of Rheumatology/European League Against Rheumatism criteria for systemic sclerosis (SSc). Demographics including gender (87% female) and age (mean of 48 years) were similar between the groups.
Overall, the African American patients showed more severe lung disease, more pulmonary hypertension, and more severe cardiac involvement than did non–African American patients, and autoantibodies were significantly different between the groups.
During follow-up, mortality proved much higher among African Americans at 21%, compared with 11% in non–African Americans (P = .005). However, the unadjusted hazard ratio for death declined from 2.061 (P = .006) to a nonsignificant 1.256 after adjustment for socioeconomic variables.
All socioeconomic measures showed significant differences between the groups. African Americans were more likely to be single and disabled at the initial study visit and to have Medicaid, but they were less likely to be a homemaker, have private insurance, or have a college degree. African Americans’ $74,000 median household income (based on ZIP code) was also a statistically significant $23,000 less than non–African American patients. But the researchers noted that “for every additional $10,000 of household income, independent of race, the hazard of death during follow-up declined by 15.5%.”
Notable differences in antibodies appeared between the groups, with more African American patients having isolated nucleolar ANA, anti-U1RNP antibody, or other positive antinuclear antibodies without SSc-specific antibodies. African American patients also were less likely to have anticentromere or anti-RNA polymerase III antibodies.
The study findings were limited by several factors, including possible bias in the matching process and the use of only index values for socioeconomic variables, the researchers noted.
Regardless of relative socioeconomic and genetic influences, “it is clear that African Americans with scleroderma merit more intensive efforts to facilitate timely diagnosis and access to continued evaluation and suppressive treatment, particularly with respect to cardiopulmonary involvement,” they wrote.
Next steps for research, according to Dr. Steen, include studying clinical subsets of African American patients to try to identify factors to predict outcomes, including the nucleolar pattern ANA, overlap with lupus, history of hypertension, and the relationship with renal crisis.
“We are also looking at whether the African American patients are less responsive to mycophenolate than the non–African American patients. We definitely need to find ways to be more aggressive at identifying and treating African American patients early in their disease,” she added.
The researchers had no financial conflicts to disclose. Dr. Steen serves on the MDedge Rheumatology Editorial Advisory Board.
SOURCE: Moore DF et al. Arthritis Care Res. 2019 March 1. .