• Distinguishing different types of inflammatory arthritis, including psoriatic arthritis (PsA) and rheumatoid arthritis (RA), can be difficult in the early stages.
• A new study reports that PsA and RA each lead to different sets of serum biomarkers — proteins found in the blood that signal the presence of a particular disease.
• These biomarkers could be used in future tests to help detect PsA early.

When psoriatic arthritis is detected and treated early, people can have better outcomes. However, it can be hard to diagnose PsA before it becomes more severe, or to distinguish it from related conditions like rheumatoid arthritis.

In a recent study published in Arthritis & Rheumatology, researchers reported they discovered a set of proteins — or biomarkers — specific to PsA. They then developed a computer program that could tell whether people had PsA or RA, based on blood samples, with a high degree of accuracy.

The discovery could result in a more reliable means of determining what type of arthritis a person has before their condition worsens. “We believe that with further development it will be possible to establish a diagnostic test for PsA that will reduce diagnostic delay, inform treatment selection, and improve both short-term and long-term outcomes,” the authors wrote in the study.

Dr. Stephen Pennington, one of the senior authors of the study, elaborated further about future plans in an email to MyPsoriasisTeam. “As the next step in the process, we are planning and trying to secure funding for a multicenter clinical validation study,” wrote Dr. Pennington, who is a professor of proteomic at University College Dublin School of Medicine in Dublin, Ireland. “We are trying to develop a protein biomarker panel that may support an early diagnosis of PsA in individuals who have psoriasis.”

Sifting Through Hundreds of Proteins

In the first phase of the study, the researchers collected blood samples from dozens of people with PsA or RA. They used three different tests, each with its own methods for measuring protein levels. Altogether, the tests analyzed levels of more than 1,000 different proteins.

From these tests, the researchers made a list of proteins that were present at different levels in people with PsA versus RA. These proteins were biomarkers that could possibly be used to tell apart the two forms of arthritis.

Next, the researchers tested whether these biomarker candidates could be used in the clinic to identify people with the two disorders. In their final analysis, the study authors measured 173 proteins in the blood of 167 people with either PsA or RA.

All of the data from this large set of proteins were combined and analyzed with a computer program. The researchers’ test was able to predict whether each blood sample was from a person with PsA or RA with a high level of accuracy.

The researchers noted that additional studies are needed to test these and other biomarkers in larger groups of people before a clinical test is available. However, they remain optimistic that a biomarker test could be useful in the future.