Contingent on antibody types, African-American patients with systemic sclerosis experience more severe interstitial lung disease than Caucasian patients and have a decreased survival rate, a study has found.
Researchers studied demographic, clinical, autoantibody, organ involvement and survival rates of 2,945 Caucasian and 203 African-American patients with systemic sclerosis (SSc) who were evaluated from 1972-2007 through the Pittsburgh Scleroderma Databank. To determine severe disease, researchers also used the Medsger Disease Severity Scale.
Researchers compared all the patients who had anti-topoisomerase 1 (topo 1), anti-U3-RNP and U1-RNP, the antibodies most frequently detected in African-American SSc patients. They found the African-American group had markedly higher frequencies of anti-topo 1 (27% vs. 21%), anti-U3-RNP (40% vs. 2%) and U1-RNP (16% vs. 7%).
- Anti-topo 1: Assessing 48 African-Americans and 490 Caucasians, pulmonary fibrosis was found more frequently in African-American SSc anti-topo 1 positive patients (72% vs. 52%, P=.0135), who also had a significantly greater frequency of severe pulmonary fibrosis (44% vs. 18%, P=.0001). After adjusting for age, gender and diffuse disease, African-American topo 1 positive patients were 75% more likely to die in five years vs. the Caucasian topo 1 positive patients (HR=2.75; 95% CI, 1.06-2.88).
- Anti-U3-RNP: Researchers compared 24 African-American and 61 Caucasian anti-U3-RNP antibody positive patients and found severe GI involvement was more common among the African-Americans. The groups showed no difference, however, in the frequency of pulmonary fibrosis and severe pulmonary fibrosis. There also was no increased risk for death at 5 years of follow-up.
- Anti-U1-RNP: Among 30 African-Americans and 148 Caucasian SSc patients, pulmonary fibrosis (74% vs. 31%, P=.0175) and severe pulmonary fibrosis (40% vs. 9%, P=.0001) were more common in the African-American patients. Five-year survival was no different between the groups.
“Our findings confirm that more serious complications affect African-Americans with systemic sclerosis than Caucasians,” Virginia Steen, MD, of the division of rheumatology and clinical immunology at Georgetown University School of Medicine, said in a news release. “For African-American systemic sclerosis patients with severe lung disease, more aggressive treatment early on could improve their outcomes.”