(RxWiki News) Rheumatic diseases affect certain populations, such as American Indians, more than others. While there are many blood tests to diagnose these conditions, some of these tests are not always useful.
Anti-CCP (a blood test used to diagnose rheumatic disease) may be a more specific sign of rheumatoid arthritis in Oklahoma tribal populations, compared to other tests.
"If you think you have arthritis - see a doctor."
Rheumatic diseases such as lupus or rheumatoid arthritis are autoimmune diseases, meaning that they happen when the body's immune system mistakenly attacks healthy tissues.
Antibodies, which are proteins involved in this immune system attack, are often measured to diagnose rheumatic diseases. However, certain antibodies are not necessarily the best sign of disease.
Judith A. James, MD, PhD, of the University of Oklahoma, and colleagues wanted to see which antibodies were the best signs of rheumatic disease among Oklahoma tribal populations.
Natives with rheumatoid arthritis were more likely than those without the disease to have anti-CCP or rheumatoid factor (RF) IgM antibodies in their blood. Both anti-CCP and RF are antibodies commonly found in people with rheumatic diseases.
More specifically, 55 percent of rheumatoid arthritis patients had anti-CCP in their blood, compared to only 2 percent of those without the disease. A total of 57 percent of rheumatoid arthritis patients had RF in their blood, compared to 10 percent of those without the disease.
Patients with anti-CCP in their blood were more likely to have higher disease activity than those without the antibody in their blood.
The researchers also found that two other antibodies (anticardiolipin antibodies and antinuclear antibodies) were more common in people with rheumatic diseases than in those without disease.
According to the authors, anti-CCP may be a more specific sign of rheumatoid arthritis in American Indian patients.
More research is needed to understand the role of anticardiolipin antibodies in rheumatic diseases, the authors concluded.
For their research, Dr. James and colleagues studied 110 Oklahoma tribal members with rheumatic disease and 110 without disease. Blood samples were taken from the participants and tested for common antibodies in rheumatic diseases. These antibodies included antinuclear antibody (ANA), anti-cyclic citrullinated peptide antibodies (anti-CCP), rheumatoid factor (RF) anti-Ro, anti-La, anti-Sm, anti-nRNP, anti-ribosomal P, anti-dsDNA and anticardiolipins.
Of those suspected of having disease, 72 percent were diagnosed with rheumatic disease: 40 (36 percent) had rheumatoid arthritis, 16 (15 percent) had lupus, eight (7 percent) had sclerdoma, eight (7 percent) had osteoarthritis, four (4 percent) had fibromyalgia, two (2 percent) had seronegative spondyloarthropathy, one had Sjögren’s syndrome and one had sarcoidosis.
The study was supported by grants from Native American Research Centers for Health, the Center of Biomedical Research Excellence, the Oklahoma Rheumatic Disease Research Core Center and the Oklahoma Autoimmunity Center of Excellence.
The research was published August 15 in the Journal of Rheumatology.