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Diagnosing PsA in a Patient with Oligoarticular Arthritis
Diagnosing PsA in a Patient with Oligoarticular Arthritis
Diagnosing PsA in a Patient with Oligoarticular Arthritis
Announcer:
You’re listening to ReachMD. This episode of Living Rheum, titled “Diagnosing PsA in a Patient with Oligoarticular Arthritis” is sponsored by Novartis US Clinical Development and Medical Affairs. The host and speaker have been compensated for their time. This program is intended for health care professionals. Here’s your host, Dr Ethan Craig.
Dr Craig:
The theme you're likely to get through our podcast series focusing on psoriatic arthritis, or PsA for short, is one of a complicated clinical endeavor. Because of its heterogeneous presentations and the absence of biomarkers, diagnosing PsA can be quite a challenge in clinical practice. So that's why in this episode, we're going to focus on a particularly vexing challenge: Diagnosing PsA in patients with oligoarticular arthritis. And we'll be honing in on some imaging features that may helped to differentiate this from other inflammatory processes.
This is ReachMD, and I’m Dr Ethan Craig. Joining me to discuss diagnosing PsA in an oligoarticular patient is Dr Alexis Ogdie. Dr Ogdie is an Associate Professor of Medicine and Epidemiology in the Perelman School of Medicine and is the director of the Penn Psoriatic Arthritis and Spondyloarthritis Program at the University of Pennsylvania. Dr Ogdie, thank you so much for being here today.
Dr Ogdie:
Thanks so much for having me.
Dr Craig:
So, I guess a good starting point to speak to the challenge of patients with oligoarticular diseases is to ask this, what do you see as the typical patterns of presentation that we may encounter in psoriatic arthritis? And how common are they?
Dr Ogdie:
Great question. So, among patients with psoriatic arthritis, and in a cross-sectional study, so taking one point in time, about half of patients have polyarticular disease and about half have oligoarticular disease, if you're looking at just the peripheral arthritis in general. So, you know, a good portion of our patients have less than 4 or 5 joints swollen or tender, which makes sense. I think if you can think about your average clinical practice, you have a couple patient - you have patients who have, you know, a couple of fingers and a toe or something like that.
In addition, there are other features that have kind of different variants, we know that all these variants kind of lay on top of each other. And instead of thinking about the original Moll and Wright subclasses, which we all learned in fellowship, we really think about the different features in addition to the inflammatory or peripheral arthritis. So, these include enthesitis so approximately half of patients will have enthesitis, at some point - on presentation or at some point - in the course of their disease. Dactylitis varies a lot more by study, but we see in general around 10% at any one point in time, but it can be up to 40 or 50% over the course of their illness. Axial disease is even more difficult to quantify, and the range differs even more greatly, be - depending on how you classify, axial disease. So, if we're looking at, x-ray changes, it's somewhere around the 20% mark among patients with PsA over the course of their illness. So that, you know, it's a relatively large amount. And then if we start thinking about non-radiographic disease, it's probably even higher, so 20 to 40%, maybe.
So, there's still a lot to learn about the actual prevalence of these different features, but we just need to keep an eye out because they do impact how we treat patients.
Dr Craig:
So then, let's start to zoom in on this particular oligoarticular subgroup. Let's take an example of a 35-year-old patient who comes into your clinic with a history of inflammatory arthritis of the left knee and right elbow. He has no current psoriasis, but previously, maybe was told that he had this red patch on his elbow with a bit of scale and was told it might be psoriasis. This is now resolved completely. He doesn't have anything present on exam. And he's wondering if this joint pain could be due to psoriatic arthritis. So, you know, Dr Ogdie, how do you approach diagnosing a patient like this, which can be a real challenge in our clinics?
Dr Ogdie:
It can. So, a diagnosis of PsA is still very difficult because there's not any one thing that clinches the diagnosis. There are classification criteria, the CASPAR criteria, which are used for studies but can be helpful just to kind of guide the diagnosis as well.
So, the first part of that is the stem which has yet to identify inflammatory arthritis. So, either peripheral arthritis, clear enthesitis, you know, a lot of people have tender entheses, but if you have clear enthesitis on imaging, for example, then spondylitis, meaning x-ray or imaging feature of spondylitis as well. So, if you have one of those things, you enter the criteria.
So, for this guy, he has inflammatory arthritis in the knee and the elbow. And as an aside, you know, a lot of people end up with a knee effusion, that can be for a variety of different reasons. So, you definitely want to tap that knee and make sure that it's inflammatory. So, in this case, I might start with that. It's just making sure that this is actual inflammation in the knee. But he also has an elbow, so clearly something more systemic is going on. Now, so he has inflammatory arthritis. What other features does he have? Does he have psoriasis? So, he may have a personal history of psoriasis. And it seems like that's a little bit questioned here. So, he has this red scale on his elbow, and let me tell you, a lot of people have that red scale on their elbow. And a lot of it's not psoriasis, it can be eczema and other things. So, you have to - you can't necessarily just take that to mean that it was psoriasis. So, what you need to do then is a full good skin exam. So, some of the places that psoriasis likes to hide are in the scalp. So, you're going to look through all of their hair, ask about dandruff, for example. You'll look in their ears because that's another place it likes to hide it’s kind of right around the rim of the ear. With masks these days, you see a lot of scaling behind the ear that people just think is related to their mask. Look in the umbilicus and then also the gluteal fold. So that's another place that people aren't just going to tell you about and you actually have to kind of look there. So, a lot of times when someone's had that scale on the elbow that just disappeared or something like that, if I'm looking around, I can find some evidence of psoriasis somewhere. Or ask the patient to take a picture the next time it appears.
So, in the criteria, we want some evidence of psoriasis, ideally at least 90% of patients have psoriasis or have had psoriasis that’s been documented, when they have psoriatic arthritis. If we're going to call it PsA, we kind of need something that psoriasis or even the nail disease, nail pitting, for example.
So next we'll look at the nails. And we'll look for pitting or onycholysis, not ridges or brittle nails, those other things. It's really those two specific features.
Dr Craig:
So, let's take the same patient and maybe stipulate that he has psoriasis. If you're trying to hone in then on a diagnosis of psoriatic arthritis here, is there any specific imaging that you find helpful in a case like this?
Dr Ogdie:
Well, ultrasound can be very helpful. So, you can see if there's inflammation of the tendon insertion, you know, enthesitis. And maybe that's part of the reason for his swelling, if it was, for example, over the medial or the lateral epicondyle, and that - the ultrasound can really help you kind of clinch that diagnosis of enthesitis. It can also tell you, if there's fronds of tissue in the knee that are suggestive of synovitis. It’s not going to help you if there's a meniscal tear so much, because it's a little harder to see, although you can see it on ultrasound., I’d get an x-ray of the sacroiliac joints. This is a young guy with potential psoriasis. I would get a good history of inflammatory back pain, but I would probably get x-rays of his sacroiliac joints. I don't do that for everybody necessarily, but I would probably do that for a young guy or someone who has back pain, at some point in the course of their joint symptoms. Maybe MRI to look for if he had back pain and a normal SI joint film, I might do an MRI of the sacrum, to get a good view of those sacroiliac joints. Other than that, I think the imaging will be largely driven by the patient's symptoms or, say, or their history.
Dr Craig:
So, in a patient like this who has, possible inflammatory arthritis of the elbow, the knee, does MRI help you there? Or is ultrasound more helpful for you in those cases?
Dr Ogdie:
Well, it depends on what's most available to you. If ultrasound is available in your clinic, that's obviously great. And so, we, can get an ultrasound relatively quickly by one of our rheumatologists. So that's helpful to me, but – and the MRI takes a little longer and it can be a little more expensive. But if you don't have ultrasound easily accessible, then an MRI could be a good step too.
Dr Craig:
So now we've spoken about some of the basics of oligoarthritis and PsA, but now let's shift over to some specific clinical topics. So, something that's not uncommon to encounter in this context, are some, possibly enthesophytes on x-ray, even in patients with osteoarthritis, so what helps to distinguish the enthesophytes you may see in osteoarthritis or diffuse idiopathic skeletal hyperostosis, DISH for short, from those that we see in PsA patients? Is there anything unique about the PsA appearance?
Dr Ogdie:
This is really challenging to kind of know what the enthesophytes on x-ray means. So, really, we want to define, enthesitis by inflammation at the tendon ligament or joint capsule insertion. And so that's where we see ultrasound or MRI being much more helpful because you can see, inflammation. In some cases, you do get that new bone formation that then is kind of bridging the joint for example. And that's, you know, ankylosing spondylitis, we see those bridging syndesmophytes, which are essentially enthesophytes. In DISH, it's a little bit different because they're very bulky, and so they tend to be a little larger and a little bit - that candle wax, drippy stuff on the spine, but you can get those over the trochanteric bursa as well. So, they're going to have trochanteric bursa pain and you look and you see those little, osteophytes hanging over the side of the pelvis there. It's really difficult.
One of the other things you often see in just many people is, enthesophytes at the calcaneus. And you see them both on the plantar fascia side as well as, near the Achilles there. And again, those are so common in the general population that you can't really use that to diagnose PsA. So, it may be suspicious in the patient with the right history, but really, I would still rely on ultrasound over x-ray enthesophytes when I'm thinking about diagnosis.
Dr Craig:
Now I think a question that often arises is how is this group of patients with oligoarthritis different? Do you see any differential patterns of disease presentation or response to therapy in the groups with oligoarticular disease as opposed to say polyarticular disease?
Dr Ogdie:
Well, there's a few things to think about. One is that polyarticular disease in general is associated with more aggressive disease, so you tend to get more erosions for example, in that group. And you know, it's harder when you have lots of joints to get their swelling down, it just takes longer because that's - it's just a numbers thing in some ways, but it may be a more aggressive form of the disease too. Oligoarticular patients, they - it doesn't - it may or may not affect their response and make them more responsive to therapy. It may be that they're just earlier in their course of the disease, and some portion of them will go on to develop polyarticular disease. So, the earlier we catch people in their disease course, the more easy to treat those patients are, or the easier to treat they are.
Some other things to think about are that when we do clinical trials, for example, we're enrolling polyarticular patients, because the outcome measures are really built for rheumatoid arthritis and polyarticular disease. And so, these oligoarticular disease patients, when you look at the outcome measures, it looks like they don't change as much. So, it actually looked like they are not as responsive to therapy. But in fact, they just have fewer joints, so they have few, you know, shorter distance to fall. So, it's something important to consider for how we study this patient population in the future.
But in general, you know, I think I would generalize and say that maybe that's a better prognostic sign to have lower joint count and that they may be, more responsive to therapy. But again, there could be multiple factors in that consideration.
Dr Craig:
Great. Well, with those final thoughts in mind, I want to thank my guest for helping us better understand oligoarthritis and PsA. Dr Ogdie, as always, it was great speaking with you today. Thank you.
Dr Ogdie:
Thanks so much for having me.
Announcer:
This industry podcast was sponsored by Novartis US Clinical Development and Medical Affairs. If you missed any part of this discussion or to find others in this series, visit reachmd.com/living-rheum. This is ReachMD. Be part of the knowledge.
How can imaging features can help us diagnose PsA in patients with oligoarticular arthritis?
Diagnosing PsA in a Patient with Oligoarticular Arthritis
Diagnosing PsA in a Patient with Oligoarticular Arthritis
For patients with oligoarticular arthritis, how can imaging features help us distinguish psoriatic arthritis from other inflammatory processes? Joining Dr. Ethan Craig to answer that question is Dr. Alexis Ogdie-Beatty from the Perelman School of Medicine at the University of Pennsylvania.
Dr. Craig and Dr. Ogdie-Beatty are Novartis consultants.
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