By Pat Anson, PNN Editor

An experimental blood test could give doctors and patients a leg up in diagnosing and treating knee osteoarthritis, years before joint damage occurs and becomes visible on X-rays.

"Currently, you've got to have an abnormal X-ray to show clear evidence of knee osteoarthritis, and by the time it shows up on X-ray, your disease has been progressing for some time," says senior author Virginia Byers Kraus, MD, a professor of Medicine, Pathology, and Orthopedic Surgery at Duke University School of Medicine.

Kraus and her colleagues have devised a test that looks for serum biomarkers in the blood that can predict – with a fair amount of accuracy – the development of knee osteoarthritis (OA) up to 8 years before joint damage occurs. Osteoarthritis is the most common form of arthritis, affecting about 10% of men and 18% of women over age 60.

In previous studies, the biomarker test demonstrated 74% accuracy in predicting knee OA progression and 85% accuracy in diagnosing knee OA. The current study further refined the test by narrowing down the number of biomarkers from a dozen to only six.

Using a UK patient database, researchers used the refined test to analyze the blood of 200 middle-aged women with no chronic knee pain; half of whom were later diagnosed with OA and the other half without the disease. The study findings, published in the journal Science Advances, show the test correctly predicted knee OA with 77% accuracy within 6 years.

"What our blood test demonstrates is that it's possible to detect this disease much earlier than our current diagnostics permit," Kraus said in a news release. "This is important because it provides more evidence that there are abnormalities in the joint that can be detected by blood biomarkers well before X-rays can detect OA.

"Early-stage osteoarthritis could provide a 'window of opportunity' in which to arrest the disease process and restore joint health."

There are currently no diagnostic blood tests for OA and there is no cure. Treatment is limited to pain relievers and anti-inflammatory drugs that slow progression of the disease.