New Blood Test Can Predict Rheumatoid Arthritis 16 Years Early

Oxford University researchers have devised a blood test that can predict the chance of developing rheumatoid arthritis up to 16 years before its onset.

The blood test created by the team, writing in the journal Annals of Rheumatic Diseases, seeks antibodies recognizing the protein tenascin-C. It could then reliably predict who will eventually suffer from the condition.

Rheumatoid arthritis occurs when, during inflammation, some proteins become altered via a process known as citrullination. These modified proteins can induce an immune reaction from one's body, whose antibodies can turn on itself.

"We knew that tenascin-C is found at high levels in the joints of people with RA," said lead study researcher Dr. Anja Schwenzer, who worked with colleagues to see if tenascin-C could be citrullinated and whether it served as a target for the autoantibodies attacking the body during RA.

At present, tests that detect antibodies to citrullinated proteins are already being used to diagnose RA. Tests for individual proteins typically have a low sensitivity rate, but cyclic-citrullinated peptide (CCP) assays, a more general test potting a synthetic citrullinated peptide, finds a lot more cases of the illness.

When they studied data from over 2,000 patients, the researchers found that testing for antibodies targeting citrullinated tenascin-C (cTNC) can diagnose rheumatoid arthritis in about half of cases, comprising those that get past CCP.

Their blood test also appeared to have a very low false positives rate, standing at 98 percent accuracy in ruling out the existence of RA.

The results allowed the researchers to also properly diagnose RA up to 16 years before the condition develops, with an average detection time of seven years before it manifests.

For Professor Kim Midwood of the Kennedy Institute, this additional test can increase CCP assay's accuracy and can enable early disease diagnosis and monitoring. "This early detection is key because early treatment is more effective," Midwood said.

Arthritis Research UK research director Stephen Simpson also delved on early diagnosis of RA as key.

"There is often a narrow 'window of opportunity' following the onset of symptoms," he said, adding that current tests are limited in ably diagnosing the painful and debilitating condition that affects the joints of about 35,000 in Britain.

The U.S. Centers for Disease Control and Prevention stated that while the cause of RA is still unknown, it could result from a combination of genetic and environmental factors. Age and sex, genetics, smoking, oral contraception, and lack of exercise are some risk factors.