Blood test finds knee osteoarthritis up to 8 years before it appears on X-rays

NEW YORK< April 26 (UPI) -- The ability to detect knee osteoarthritis with a blood test up to eight years before it appears on X-rays -- as researchers have done -- could lead to therapies that delay disease progression and restore joint health, a new study finds.

Results of the study, conducted by Duke University School of Medicine in Durham, N.C., were published Friday in Science Advances.

Researchers confirmed the blood test's validity in identifying key biomarkers of osteoarthritis. They established they could foretell the disease's development, as well as its progression, which they noted in earlier work.

Such a scientific advance would be of higher caliber than current diagnostic tools, which often don't identify osteoarthritis until it has led to structural joint damage, the researchers said.

"These findings demonstrate that the disease process of osteoarthritis can precede symptoms and X-ray changes that we typically associate with a diagnosis," said the study's senior author, Dr. Virginia Byers Kraus.

"This represents a shift from current thinking that osteoarthritis begins when an X-ray shows abnormalities," such as loss of cartilage, formation of spurs and thickening of bone beneath the cartilage layer," said Kraus, a professor of medicine and adjunct professor of orthopedics and pathology at Duke University School of Medicine.

As the most common form of arthritis, osteoarthritis affects 32.5 million U.S. adults, most frequently occurring in their hands, hips and knees, according to the Centers for Disease Control and Prevention.

Pain, stiffness and swelling could limit function and lead to disability, the CDC says.

The study proved what the researchers expected -- that "very early osteoarthritis is silent and hiding in plain sight," Kraus said. That's because cartilage tissue doesn't have nerves and can deteriorate early "without giving off pain-related danger signals."

Once an X-ray displays signs of osteoarthritis, "these changes are irreversible," she said. "Current treatments can only control symptoms."

Kraus stressed that it will be easier to slow or halt the disease process if doctors can encourage patients to take preventive measures.

The molecular biomarkers that Kraus and her colleagues focused on investigating are useful for clinical diagnostic purposes and as a research tool to aid in the development of effective drugs, the researchers said.

In previous studies, the blood biomarker test was 74% accurate in predicting progression of knee osteoarthritis and 85% accurate in diagnosing knee osteoarthritis.

The current study fine-tuned the test's predictive capabilities. Researchers analyzed serum of 200 White women from a United Kingdom database. Half of them had a diagnosis of osteoarthritis. The groups were matched by body mass index and age.

Researchers discovered that a small number of biomarkers in the blood test correctly distinguished women with knee osteoarthritis from those free of the disease up to eight years later. As a result, the test caught molecular signals of osteoarthritis well before X-rays detected the disease in many of them.

"Because osteoarthritis is a complex disease, we were surprised that we could robustly predict early osteoarthritis risk with as few as two to six blood biomarkers," Kraus said.

"We are hoping that in five or so years, we could have enough validation and experience with the [blood test] panel to make the test available to the general public for predicting risk of developing osteoarthritis X-ray changes," she added.

Jason Kim, vice president of osteoarthritis research at the Arthritis Foundation in Atlanta, told UPI via email that "this is an important study performed by one of the top clinician-researchers in osteoarthritis biomarkers with implications for the future treatment of osteoarthritis." He was not involved in the new study.

Kim said "early detection of knee osteoarthritis could help clinicians intervene sooner and reduce the pain and loss of function of patients before joint replacement surgery is necessitated."

The new discovery is "really at the forefront of moving beyond our current simple diagnostic tools looking at knee osteoarthritis and moving into the era of biomarkers and genetic understanding of arthritis," said Dr. Jonathan Vigdorchik, a hip and knee surgeon at the Hospital for Special Surgery in New York City.

"We used to think knee osteoarthritis was just wear and tear of the knee joint over time," Vigdorchik said. "However, there may be more to the story."

In addition, an overactivated immune response can result in joint inflammation, said Dr. Kimberly Templeton, vice chair of orthopaedic surgery at the University of Kansas Health System in Kansas City, Kan.

"Osteoarthritis has a significant inflammatory component," said Templeton, a past president of the American Medical Women's Association.

She added that low-grade inflammation in people who are overweight or obese may augment the risk of developing osteoarthritis. This should be even more concerning for women with osteoarthritis, as they are more likely to have other health conditions related to inflammation, including cardiovascular disease.

"There is currently no cure for osteoarthritis or ways to help cartilage heal and replace damaged areas," Templeton said. "However, if we can predict patients at risk early in the course of osteoarthritis, we can focus on areas such as weight loss and exercise to help halt or slow the process."

Patients who are overweight may be more inclined to lose weight when informed of their elevated risk of developing knee osteoarthritis due to their weight and the presence of biomarkers, said Dr. C. Lowry Barnes, chair of the Department of Orthopedic Surgery at the University of Arkansas for Medical Sciences in Little Rock.

Even patients of normal weight with the biomarkers "might be more diligent in quadriceps strengthening, which may decrease the symptoms of arthritis of the knee," Barnes said.

The biomarkers ultimately could clue researchers into the "mechanisms responsible for the occurrence and progression of osteoarthritis of the knee," said Dr. Joseph Huffstutter, a rheumatologist who is a partner and lab director at Arthritis Associates PLLC in Hixson, Tenn.

"If we can understand what causes these elevations, then it may be possible to develop true disease-modifying medications that will act to slow or stop the progression of osteoarthritis," Huffstutter said.

While the study was well designed, it analyzed a total of only 200 White women from London, said Dr. Jason Koh, director of Endeavor Health Orthopaedic & Spine Institute in Chicago's northern suburbs.

"There may some limitations in generalizing these findings to a more diverse population," said Koh, who also is a clinical professor of orthopaedic surgery at the University of Chicago Pritzker School of Medicine.

"But, " he added, it's "a very interesting and provocative study."