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New Test Detects Osteoarthritis Faster

Marker for joint disease found in blood and urine

FRIDAY, Oct. 4, 2002 (HealthDayNews) -- An international team of researchers has discovered that telltale signs of the painful joint disease osteoarthritis can be found in samples of blood and urine.

The study, published in the current issue of Arthritis and Rheumatism, found that osteoarthritis causes changes in the levels of two markers of collagen production and metabolism. Collagen is a component of cartilage.

"What this study clearly shows is that there are biological markers for cartilage synthesis and degradation, and that they are present in osteoarthritis," says Dr. John Klippel, medical director of the Arthritis Foundation. Klippel was not involved in the current research.

Osteoarthritis is a disorder caused by the destruction of the cartilage that cushions the joints. As cartilage wears away, bones begin to rub together. The condition can cause pain, swelling, stiffness, and loss of motion. More than 20 million Americans suffer from osteoarthritis, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Half of all Americans have osteoarthritis in at least one joint by the age of 65. There is no treatment to halt the progression of osteoarthritis, only to manage its symptoms.

Currently, the only way to diagnose osteoarthritis is through X-rays, CT scans or MRIs, Klippel says. The problem with relying on these methods is that it takes a lot of time before any changes in cartilage become evident, and by that time the damage is already done. Also, researchers cannot quickly assess whether new treatments are effective or not.

For the current study, researchers from France, Denmark and the United States recruited 75 men and women with osteoarthritis of the knee and 58 people without the disorder to act as a control group. The average age of the participants was 63.

Blood and urine samples were taken at the start of the study and one year later. The researchers also took X-rays and surgically examined the knee using arthroscopy.

The researchers found that people with osteoarthritis had lower levels of a substance that helps with cartilage production and higher levels of a substance that causes cartilage degradation.

"It's nice to finally have a marker," says Dr. Robert Quinet, head of rheumatology at Ochsner Clinic Foundation in New Orleans. "People have been interested in finding markers for many years. This is the best study so far, but there's no therapy to use. We don't yet have a drug that will impact on these findings."

A more immediate use of these tests would likely be in clinical trials, Quinet and Klippel say. With current diagnostic techniques, months or years have to pass before any changes in the disease progression can be noticed, says Klippel. So, if these biological markers of osteoarthritis are confirmed in larger trials, they could help researchers more quickly assess if a particular treatment is working or not.

The authors of the study acknowledge that their sample size was relatively small, and since they only studied osteoarthritis of the knee, they don't know if these markers would be present in other forms of the disease. They also conclude that larger studies need to be done to confirm their findings.

Those limitations don't dampen Klippel's enthusiasm for the work, however. "This has the potential to become important in the evaluation and care of people with [osteoarthritis] and similarly will be important in the conduct of clinical trials," he says.

What To Do

For more information on osteoarthritis, visit the National Institute of Arthritis and Musculoskeletal and Skin Diseases or the American College of Rheumatology.

SOURCES: John Klippel, M.D., medical director, Arthritis Foundation, Atlanta; Robert Quinet, M.D., head, rheumatology, Ochsner Clinic Foundation, New Orleans; October 2002 Arthritis and Rheumatism
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