How can we tell who will get psoriatic arthritis? Science.

| Melissa Leavitt

Wouldn’t it be great if you could know for certain whether you are going to develop psoriatic arthritis?

Research has shown that if psoriatic arthritis is left untreated, it can lead to severe bone and joint damage, and even disability. Waiting to begin treatment as little as six months after symptoms first appear could make your health outcomes significantly worse.

Unfortunately, there are still no definitive tests to diagnose PsA. Dermatologists may not always check for joint symptoms in their psoriasis patients. Even when they do, those early signs might take a variety of different forms, from pitting in the fingernails to an oversized pinky toe.

There’s no great big neon sign with flashing lights saying “psoriatic arthritis.” Scientists are working to build that sign by identifying biomarkers for the disease. Biomarkers are biological signs that signal the presence of a disease in the body.

For psoriatic arthritis, these biomarkers could show up in the skin, blood or joints. Eventually, these biomarkers could serve as a scientific crystal ball, allowing doctors to test their psoriasis patients for these biological signs to predict whether someone will develop psoriatic arthritis—even before the patient notices any symptoms.

Predicting the future of PsA

A group of researchers from the University of Toronto published a study identifying proteins in the synovial fluid—fluid found in the synovial joints, the most common joint in the body—that may point to psoriatic arthritis.

The researchers compared the synovial fluid of psoriatic arthritis patients with the synovial fluid of patients with a different kind of arthritis, osteoarthritis. According to the results, published in the journal Clinical Proteomics in 2014, they found 12 proteins that seemed to be unique to psoriatic arthritis.

These proteins could one day be used as biomarkers to differentiate psoriatic arthritis from a different form of arthritis. But what about diagnosing psoriatic arthritis in the people most likely to get it—psoriasis patients?

The same group of researchers published another study in Clinical Proteomics in January 2015 identifying eight proteins that are in the skin of people with psoriatic arthritis—but not in the skin of people who only have skin psoriasis. In time, a doctor might search for these proteins in your skin to tell you whether you should be on the lookout for arthritis symptoms.

But wait, there's more.

Biomarkers might be used for more than diagnosing a disease—they could also tell you how to treat it. Researchers at the Mayo Institute have begun work identifying biomarkers that might predict how a patient will respond to a certain kind of treatment.

Led by Dr. Timothy Niewold, the team tested the blood of about 140 patients and found that levels of a certain protein, known as a type 1 interferon, could indicate whether a patient will respond to treatment with a kind of biologic medication, such as Humira (adalimumab) or Enbrel (etanercept), known as a tumor necrosis factor-alpha blocker, Niewold said.

“It’s exciting because it’s one of the grails that everyone’s been chasing,” Niewold said. “If you could measure something beforehand, maybe that would make you smarter about which medication to choose at the outset.”

Currently, Niewold said doctors have to wait until time has passed to know whether a treatment is working. “It’s like getting a weather forecast when you’re already standing outside,” he explained.

His team tested rheumatoid arthritis patients, not patients with psoriatic disease. But the next steps are seeing whether this test might also be useful for other conditions, including psoriasis, psoriatic arthritis and inflammatory bowel disease, Niewold said.

The blood test is fairly complicated, he explained, and for that reason, it could be a while before it comes to the clinic. As with the diagnostic biomarker tests, the treatment response biomarker test isn’t something patients can benefit from just yet.

One day, these tests could help doctors better understand the causes and mechanisms of psoriatic disease—and deliver even better care to patients. Until then, keep watching for the signs and symptoms of disease progression, and let your doctor know what’s going on.

Driving discovery, creating community

For more than 50 years, we’ve been driving efforts to cure psoriatic disease and improve the lives of those affected. But there’s still plenty to do! Learn how you can help our advocacy team shape the laws and policies that affect people with psoriasis and psoriatic arthritis – in your state and across the country. Help us raise funds to support research by joining Team NPF, where you can walk, run, cycle, play bingo or create your own fundraising event. If you or someone you love needs free, personalized support for living a healthier life with psoriatic disease, contact our Patient Navigation Center. And keep the National Psoriasis Foundation going strong by making a donation today. Together, we will find a cure.

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