Diagnosing Psoriatic Arthritis


Anthony M. Turkiewicz, MD, leads the discussion on diagnosing psoriatic arthritis (PsA), including differentiating PsA from axial spondyloarthritis, and comments on the role of CASPAR criteria in clinical practice.

Anthony M. Turkiewicz, MD: Discussing psoriatic arthritis [PsA] as part of the spondyloarthropathy family, it’s one of the main players in it. There were some discussion points about how we differentiate psoriatic arthritis from, say axSpA [axial spondyloarthritis], whether it be nonradiographic axSpA or radiographic axSpA. I’ll field this one. It’s a question that it does come up from time to time, particularly with those patients where you’ll have a psoriatic spondylitis, which we know can occur, the numbers say about 30%. We’re not sure we see it that often, and we see a lot of patients with psoriatic arthritis. How their inflammatory back pain manifests may come down the line, and sometimes it is their presenting symptom.

For differentiating this, it’s easy when it’s established, so we learn from the phenotypic expressions of psoriatic spondylitis vs true ankylosing spondylitis, or radiographic axSpA, that there are some features. PsA is typically asymmetrical. If you get to the syndesmophyte formations, which again is more chronic, you’re lucky, not lucky for the patient, but lucky enough for the doctor to see it. Typically, you’ll have the thin or sealed lines in a patient with axSpA or radiographic axSpA vs say the water jug, thicker handle and get asymmetric involvement in PsA.

Clinically, psoriatic arthritis, the reason we put it in the peripheral SpA category, it typically is more focal. You can get enthesitis in both psoriatic arthritis and axial SpA. Dactylitis is slim to none in a patient with PsA. There are some physical manifestations that can be different between the two. For the most part axial spondyloarthritis, whether it’s nonradiographic or radiographic, the patients’ complaints are primarily typically of some type of inflammatory back pain. They can get peripheral involvement, but again the focus is on their axial complaints.

There’s a question about CASPAR [classification criteria for psoriatic arthritis] criteria, what role that plays, and in the clinical setting, not much. We all do clinical trials. CASPAR criteria were, I wouldn’t say a welcome change from the Moll and Wright criteria, but they did make enrollment into psoriatic clinical trials easier. Particularly with the boom of biologics and small molecules, the CASPAR criteria probably made it a little more homogenous, a little easier to identify these patients for clinical trials. In my personal experience in the clinic, I’m not typically going by CASPAR criteria. We know they are a classification criteria by definition. They can form a framework from which we can start getting some clues to think this is going down a PsA pathway.

Any thoughts on that from you all in general? Whether there’s a certain diagnostic...do you use CASPAR criteria? Len, in your clinic, what are your thoughts?

Leonard H. Calabrese, DO: I generally do not use them, but my diagnostic reasoning follows it. Rheumatologists are good at recognizing plaque psoriasis, psoriasis vulgaris. I don’t feel as confident with inverse psoriasis, guttate psoriasis, etc. When it’s on the line or it’s atypical, I get my dermatologist buddies to throw down on that. Once you have that, then being seronegative and documenting the presence of objective joint disease is easy. We’ll probably come back to this, that rheumatologist/dermatologist cooperation. But in the presence of clear psoriasis, we recognize arthritis, enthesitis, dactylitis, spondylitis, etc. That forms the basis of what I’m thinking.

Sheetal Desai, MD: I agree, and I feel like these criteria definitely help our PCPs [primary care providers], our dermatologists. They help the fellows. I feel like the fellows refer to a lot of these criteria when they’re still in training and trying to feel comfortable. I agree with Len, we’re so comfortable with these conditions that we do follow them for the most part without actually having to say patients meet a certain amount of CASPAR criteria.

Transcript Edited for Clarity

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