Psoriatic Arthritis: Assessing Disease Severity

Lana Dykes: What are the clinical manifestations of psoriatic arthritis, and how is disease severity assessed?

Christopher Parker, DO: In terms of the different types of psoriatic arthritis, or other manifestations, again, this is one of the fun parts of rheumatology. You can’t just talk to somebody and not touch them. We really need to hear, see, touch, and use imaging modalities and laboratory tests and stuff like that.

Many patients will come to me with skin issues and joint issues, and it’s up to me to understand if the joint issues, for example, are truly an articular problem, a joint problem. So I’m looking for swelling, and I’m looking for warmth. I might look for changes in range of motion. One of the interesting things about musculoskeletal problems associated with psoriasis is they really like to get enthesitis. That’s inflammation at the junction of the tendon to bone or ligament to bone. Patients are going to say the joint hurts either way, but it takes an examiner to understand, for example, is it in the actual elbow joint, or is it where these forearm extenders attach—what someone might call tennis elbow or lateral epicondylitis? That’d be more of an enthesitis situation. Or, you could have both. Some dogs have ticks and fleas, and that certainly applies here. You could have a joint problem and an enthesitis or tendon problem all at the same time. So, I think of those things.

Psoriatic arthritis likes to cause something called dactylitis inflammation of an entire dactyl, meaning a toe or finger. This makes the toe or finger look like a sausage. Sometimes we call it sausage digit. I alluded earlier to damage, and some people, unfortunately, get such destructive psoriatic arthritis that it’s called arthritis mutilans because it’s really destroyed and deformed. And so, that’s a possibility. But happily, this is uncommon. Those are the types of things I think about.

Let me also say a word about the difference between axial disease, meaning of the spine, and peripheral disease, meaning outside the spine—the smaller joints. A patient with psoriatic arthritis may have only axial disease, meaning back pain issues, or they could have only peripheral disease, or they may have both. It’s up to me to help understand where all of the spots are. If it’s an older patient, the challenge becomes trying to understand if somebody’s back pain is degenerative, meaning just normal wear and tear, and/or concomitant inflammatory back pain. Because again, you can have both. It’s very important to figure that out because, naturally, the treatments are different. You don’t need to add more anti-inflammatory treatment if the problem is degenerative. So, there’s a lot going on in that regard.

Lana Dykes: How is the disease severity assessed?

Christopher Parker, DO: I’ll give some thoughts on this. I realize many academic rheumatologists have different numerical ways to determine disease activity, and I’m all for that. I don’t think there’s 1 right way. Certainly, we should count the joints with issues and measure them over time. I definitely don’t have a measuring strategy in my clinic for the skin. As I mentioned earlier, I let the patient try to help me understand how happy they are with the skin part, rather than me coming up with a number. I realize you can say, “Well, that’s about 1%...your hand.” Then I could see if they got 3%, or 5%, or however many percent, but ultimately, if they’re happy and they really want to focus on joins only, then that’s what I’m going to do.

I want to talk about a couple of other things I think are very important. I’m a big believer in doing patient-associated outcomes, or patient-described outcomes, and measuring those. Since 1997, I do a modified health assessment questionnaire on every patient during every visit. They know they’re going to get asked, and they fill it out quickly. It’s a semiquantitative way to assess common activities of daily living. How easy is it for you to dress yourself, tie your shoelaces, do buttons, and walk outdoors on flat ground? I want to explore all of those things. Hopefully, if they come in pretty sick, as I start getting them better, those should improve over time. And then all of it, together, everything the patient describes and everything I can see on examination should ultimately, in my simple mind, result in a physician global assessment. To me, that’s a super valuable thing—to say, “Yeah, my patient’s definitely better.” Or, “My patient’s in remission or has low disease activity.” That is super important, and I think we sometimes forget about that.

Transcript edited for clarity.