Blood Test May Predict Rheumatoid Arthritis
Antibodies signal disease before symptoms appear, finds study
FRIDAY, Oct. 3, 2003 (HealthDayNews) -- The presence of certain antibodies in the blood may signal the development of rheumatoid arthritis years before symptoms begin.
That's the conclusion of a new study published in the October issue of Arthritis and Rheumatism, which found one-third of people with rheumatoid arthritis had antibodies, called anti-CCP antibodies, in their blood long before they ever felt the first symptoms of the disease.
Currently, doctors diagnose rheumatoid arthritis based on symptoms and the presence of rheumatoid factor in the blood. This means that most people aren't diagnosed with the disease until they've had the disorder for some time. Additionally, not everyone who has rheumatoid arthritis tests positive for rheumatoid factor.
"The anti-CCP test may help us detect patients who have early rheumatoid arthritis better than rheumatoid factor, and it may also predict patients who have more progressive disease," says Dr. Clifton O. Bingham III, director of the Seligman Center for Advanced Therapeutics at the NYU-Hospital for Joint Diseases in New York City.
More than 2 million Americans have rheumatoid arthritis, according to the Arthritis Foundation. Nearly three times as many women as men have the disease. The disease begins most often in middle age, but can be seen in children and young adults.
Common symptoms of rheumatoid arthritis are joint stiffness, particularly in the small joints like those in the fingers and wrists, joint pain and swelling. Bingham says if you have joint stiffness when you first wake up and it lasts for more than a half an hour, and this symptom has been occurring for more than six weeks, you should be evaluated by a doctor.
In the current study, researchers from University Hospital in Umea, Sweden, examined data from the Northern Sweden Health and Disease Study and the Maternity cohorts of Northern Sweden. They found 83 people who had donated blood several years before being diagnosed with rheumatoid arthritis.
The researchers analyzed samples of the blood taken from these 83 people before they had symptoms of rheumatoid arthritis. The average time between when the blood sample was taken and the diagnosis of rheumatoid arthritis was 2.5 years.
Thirty-four percent of the people who developed rheumatoid arthritis tested positive for anti-CCP antibodies. And the closer the blood samples were taken to the onset of symptoms, the more frequently the blood tested positive for anti-CCP antibodies.
When the researchers looked for the presence of anti-CCP antibodies in conjunction with rheumatoid factor, their ability to predict who would eventually develop rheumatoid arthritis was nearly 100 percent.
Finding rheumatoid arthritis early is very important, Bingham says.
"Joint damage and destruction occur early in the disease process," he says, adding that "a growing body of data is showing that early treatment will lead to a better long-term prognosis."
Not everyone believes an additional test is necessary, however.
Dr. Berj Nercessian, a rheumatologist at William Beaumont Hospital in Royal Oak, Mich., says he doesn't believe this test would help him diagnose rheumatoid arthritis more efficiently.
"The diagnosis of rheumatoid arthritis is based on a whole constellation of symptoms that are present and by blood tests," says Nercessian. "The blood test is just an additional test to confirm the diagnosis."
However, he does say it might be helpful in situations where a diagnosis is not clear. For example, he says that many times it's difficult to tell if someone has lupus or rheumatoid arthritis, since many of the symptoms and blood tests are similar. If anti-CCP antibodies are exclusive to rheumatoid arthritis, then Nercessian says it could help doctors distinguish between the two diseases.
But, he adds, whether these antibodies are exclusive to rheumatoid arthritis is a question that still needs to be answered.
Bingham says there are some limitations to this test because some people who have rheumatoid arthritis won't test positive for these antibodies and a few people who do test positive may never develop rheumatoid arthritis.
Still, Bingham says, "the anti-CCP antibodies test is going to be very useful as a diagnostic test."
To learn more about rheumatoid arthritis, visit the Arthritis Foundation or the National Institute of Arthritis and Musculoskeletal and Skin Diseases.