This video discusses the overlapping pathogenesis of psoriasis (PsO) and psoriatic arthritis (PsA), highlighting the importance of interdisciplinary care in managing these conditions.

Transcript: 

Hello, and thank you for joining us today. My name is Dr Saakshi Khattri. I'm a board-certified dermatologist and rheumatologist at the Icahn School of Medicine at Mount Sinai in New York City.

In this video, we will focus our discussion on psoriasis and psoriatic arthritis, the overlapping pathogenesis involved, shared comorbidities between these diseases. We will also highlight the importance of collaboration between specialties when treating patients with psoriasis and psoriatic arthritis. Let's get started first with psoriasis.

Psoriasis is a chronic inflammatory skin disease that affects about 3% of adults in the United States. The most common type is plaque psoriasis, and clinically it looks like erythematous, scaly, well-defined plaques, often on the elbows and knees, scalp. But really, anywhere you have skin, you can have psoriasis. Psoriatic arthritis, on the other hand, is an inflammatory arthritis.

It is with, you know, when you have inflammatory arthritis, there's joint swelling, there's joint tenderness, and eventually there could be irreparable damage in the form of erosions and joint space narrowing, which all ultimately leads to joint destruction. Psoriatic arthritis is seen in about 30% of patients that have psoriasis, and generally, in 90% of cases, you have psoriasis that precedes the development of psoriatic arthritis. And, you know, the transition from psoriasis to psoriatic arthritis can take as long as 10 years.

So, this highlights the importance of close monitoring for earlier detection, hopefully, of psoriatic arthritis or earlier referral to rheumatology when you suspect psoriatic arthritis in a patient that has psoriasis that you're seeing in your practice. In terms of the overlapping pathogenesis associated with diseases, we have many cytokines that are involved in the pathogenesis of both psoriasis and psoriatic arthritis, and that's why we have targeted therapies such as biologics and small molecules for treatment of both these diseases. TNF-alpha, or tumor necrosis factor alpha, was long considered the main immunological mediator in this inflammatory cascade, and the first class of biologic therapies were approved for both psoriasis and psoriatic arthritis that blocked TNF-alpha.

Since then, we've had other cytokines that have come into play. IL-17, again, is a predominant cytokine as well. And then you have IL-23, which is a cytokine that regulates the production of IL-17 by activating TH-17 helper cells.

In terms of a diagnosis for both these diseases, generally, psoriasis is a clinical diagnosis to make. Now, diagnosing psoriatic arthritis, now, that's a challenge. Certainly, as a rheumatologist, I will say that because we don't have a blood test or a biomarker for psoriatic arthritis, psoriatic arthritis really, at the end of the day, still is a clinical diagnosis.

And I can only imagine, for my non-rheumatologist colleagues, my dermatologists, diagnosing psoriatic arthritis is even a greater challenge just because of the knowledge gap that exists. So, I tell all my derm colleagues that just asking questions, if there's a new onset joint pain that a patient with psoriasis reports, it should clue you in that it's time to consider psoriatic arthritis as a possibility. An early referral is helpful because even a 6-month delay in diagnosing psoriatic arthritis does irreparable damage to joints.

There is a PEST questionnaire, which is a validated screening questionnaire, which we can hand out to our psoriasis patients while they're waiting to be seen. A score of 3 or higher, we can certainly siphon those patients to a rheumatologist earlier, as opposed to those that don't have a 3 or higher score. So, that can be one way of, you know, an earlier detection, hopefully, of psoriatic arthritis.

And then secondly, just asking for joint pain, morning stiffness, and generally, the cutoff is 30 minutes or longer. So, this is this is stiffness in the morning when you wake up or stiffness after periods of inexertion, and if a patient says that, you know, they're stiff for 30 minutes or longer, or even hours or the whole day, then you should start thinking of an inflammatory arthritis and certainly send those patients to a rheumatologist sooner rather than later.

Now, you know, we've talked about the challenges associated with diagnosis of psoriatic arthritis, and you know, we've sort of talked about psoriatic arthritis being this main comorbidity that's seen in patients that have psoriasis. But let us not forget that we also have other associations with psoriasis, namely that span the metabolic syndrome umbrella. Cardiovascular disease, dyslipidemia, diabetes, and even malignancy are some things you consider when you're seeing patients that have psoriasis.

But another way to sort of navigate the challenge is to partner effectively with colleagues from different specialties. Certainly, interdisciplinary clinics that span both rheumatology and dermatology are being seen more and more in certain academic institutions. And, you know, having rheums and derms work closely when they see patients that have psoriasis and psoriatic arthritis can certainly improve outcomes for our patients.

Patients are certainly happier to see both a rheum and a derm under the same roof, and you know, that partnership is helpful because that earlier diagnosis of psoriatic arthritis can also be seen when you have these cross-specialty or cross-collaboration clinics. Thank you so much for listening in today to review this important topic.