London: A simple blood test for the most common form of arthritis that can detect the condition several years before the onset of physical symptoms may soon be available, UK researchers say.
The research by the University of Warwick identified a biomarker linked to osteoarthritis, the most common form of arthritis, and rheumatoid arthritis.
While there are established tests for rheumatoid arthritis (RA), the newly identified biomarker could lead to one which can diagnose both rheumatoid arthritis and osteoarthritis (OA).
The research's focus was citrullinated proteins (CPs), a biomarker suspected to be present in blood of people with early stage rheumatoid arthritis.
It had previously been established that patients with RA have antibodies to CPs, but it was not thought that this was the same for those with OA.
However, the Warwick researchers found for the first time increased CPs levels in both early-stage OA and RA.
They then produced an algorithm of three biomarkers, CPs, anti-CP antibodies along with, the bone-derived substance, hydroxyproline.
Using the algorithm the researchers found that with a single test they could potentially detect and discriminate between the major types of arthritis at the early stages, before joint damage has occurred.
"This is a remarkable and unexpected finding. It could help bring early-stage and appropriate treatment for arthritis which gives the best chance of effective treatment," said lead researcher, Dr Naila Rabbani.
"It has been long established that the autoimmunity of early-stage RA leads to antibodies to CPs, but the autoimmunity, and hence antibodies, are absent in early-stage OA.
"Using this knowledge and applying the algorithm of biomarkers we developed provides the basis to discriminate between these two major types of arthritis at an early stage," Rabbani said.
The ability to discriminate between RA and OA could provide a number of benefits to patients, including early diagnosis.
"Detection of early stage-OA made the study very promising and we would have been satisfied with this only ? but beyond this we also found we could detect and discriminate early-stage RA and other inflammatory joint diseases at the same," Rabbani said.
"This discovery raises the potential of a blood test that can help diagnose both RA and OA several years before the onset of physical symptoms," Rabbani added.
The research is published in the journal Nature Scientific Reports.