The Benefits and Limitations of the PASI Score

Maria Lopes, MD, MS, provides an overview of the PASI scoring system.

Ryan Haumschild, PharmD, MS, MBA: Let’s transition the discussion to treatment considerations. Let’s discuss the importance of treatment considerations and patient perspective when we’re selecting sequencing treatments. Dr Lopes, how does the PASI [Psoriasis Area and Severity Index] score measure the level of severity for psoriasis? What limitations exist with using this scoring system in darker-skin prototypes? Maybe there’s less diagnosis because fewer clinicians have been trained in it.

Maria Lopes, MD, MS: That’s a great question. PASI score is a measure of the level of severity. It stands for Psoriasis Area Severity Index. It looks at 3 dimensions, erythema, induration, and scaling or discrimination. Each area is graded under the 0-to-4 scale. The higher the score, the higher the severity. It’s also scored based on the 4 body parts: the head, the arms, the trunk, and the extremities, like legs. It’s usually used as a measure of severity. It’s also used to look at improvement, especially across different treatment options. In real-world practice, I don’t think it’s used often, but it’s something payers rely on to look at the level of improvement as we look at different treatment options.

It’s also used to define mild, moderate, and severe, and hence the appropriate treatment approach for each indication. One element that it does not capture is itching. And that’s becoming, I think more recognized. With data usually comes the recognition of how important itching is to patients and what it means for things like sleep, quality of life, and managing stress overall. It doesn’t capture all symptoms, but what Dr McMichael stated is absolutely correct. In people of darker skin color, how do you appreciate erythema? That may go unnoticed, and therefore it may be scored at a lower level because you’re missing a big dimension and a big component as well as other elements that are critically important to the management of these patients.

Ryan Haumschild, PharmD, MS, MBA: Excellent. It sounds like there’s a lot of opportunity when we’re selecting treatment and making sure that we’re following up with these patients. Dr McMichael, I want to come back to you because you talked a lot about great things, like how to diagnose these patients and what we should be looking for. From your perspective, what are the goals of therapies for patients with psoriasis? How do you assess if treatment is successful or if we need to pivot to another therapy?

Amy McMichael, MD: Great question. I speak with the patient and find out what their goals are. I have patients who come in and have [psoriasis on] 5% to 10% [of their] total body surface area, in areas typically covered by clothing. They’re not particularly itchy, and they demand to have a biologic. They may not have tried topical agents. They may not have tried anything systemic by that time, but they’ve seen the biologic commercials, so they think, “This is for me. I want to do that.” We have to talk about what makes the most sense. What are our goals? If you’re not particularly worried about it, but it's worrisome to have this disease, perhaps they have other reasons why they’re concerned. Leaving lots of scales and those sorts of things can be very embarrassing, both at home and at work. How can we take what we have in our armamentarium of drugs and fit it to what your needs are, with the idea that we can always move to the next more aggressive, more systemic treatment? It’s about the first conversation that you have with a patient when you’re introduced to them.

On the other hand, I have patients who have [psoriasis on] 50%, 60%, or 80% [of their] total body surface area. They say, “Doc, if you can get me to stop itching, I’m good.” It has to be a decision between the physician and their patient about where their goals need to be. Once you’ve decided those things, you have to be a little more likely to use systemic agents and patients of color, particularly because of the thickness, the extent, and the visibility of the lesions when they’re on the scalp. The pigmentation can be hypopigmented as well as hyperpigmented. Having significant hypopigmentation extending onto the forehead and behind the neck and places that are quite visible for individuals is really distressing. For some patients, even if they don’t have a large disease burden, aggressively treating those visible areas of disease is very important. It’s very tailored to the patient. When patients are comfortable, they’re not itching, they’re not having pain in their lesions, and they’re not breeding scale everywhere—that’s how we measure if they’re better.

For a number of patients we treat, we get their skin lesions quite flat. They don’t have active scaling, they don’t have erythema, and they don’t have symptoms, but they have postinflammatory hyperpigmentation. A post-treatment pigment that’s remaining in areas that can be quite visible. Those patients are some of the hardest to address because the disease is under control. But the aftereffect is lingering. In those patients, you have to say, “What can we do for postinflammatory hyperpigmentation?” That’s why it’s so important to see a board-certified dermatologist who can handle not just getting you on the right medication but also all the things that come afterward, in terms of your skin findings.

It’s also important to involve the patient in the national organizations that support patients. That makes them feel more comfortable about the fact that they’re not the only ones affected. That’s a big part of my treatment, letting patients know that there’s an organization that can help. They talk about all the things that you have, that you’re not in this alone. They talk about all the new and important treatments coming along, the trials that are still in play, and all that. That helps patients as well.

Ryan Haumschild, PharmD, MS, MBA: You said so many good things in that answer, but 1 that stood out was patient-centered care. You’re meeting with that patient, you’re understanding what their goals are for care along with you as the provider, and then coming up with shared decision-making on what the outcome is going to be. What should our therapy be? You also made a really good comment about using systemic therapy, especially in unique patient populations, and how we need to be thoughtful of health equity and considerate of the patient’s background, not just treating every patient differently. Thank you for going through that with us. I appreciate that.

Transcript edited for clarity.

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