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In the past, psoriasis was largely categorized as mild, moderate, or severe, based on body surface area (BSA) alone, but there’s more to psoriasis than just BSA. Ignoring other aspects of the disease that affect quality of life, such as the involvement of special areas (scalp, palms and soles, genitals, and nails), may mean that many patients who could or should benefit from biologics in the clinic or clinical trial participation are not getting the care they need.

To improve access and update guidelines so that they are more in-line with what dermatologists who regularly treat psoriasis are seeing in the clinic, Bruce Strober, MD, PhD and colleagues, on behalf of International Psoriasis Council Board Members and Councilors, redefined the classification of psoriasis severity via a Delphi exercise.

Dr. Strober, co-founder of Central Connecticut Dermatology and Clinical Professor of Dermatology at Yale University School of Medicine in New Haven, spoke to Practical Dermatology® magazine about this new way of thinking about psoriasis severity.

Why did you feel it was imperative to recategorize psoriasis severity?

Bruce Strober MD: Psoriasis severity traditionally is defined as “mild,” “moderate,” “moderate-to-severe,” or “severe.” Severity classifications traditionally are guided by stringent cutoffs based on the BSA of psoriasis involvement with “moderate-to-severe” or “severe” generally held to be BSA greater than or equal to 10 percent—the minimum level to get into almost all clinical trials for pipeline psoriasis drugs. However, “mild” or “mild-to-moderate”—often defined as less than 10 percent BSA—underestimates disease severity if psoriasis involves “special areas” (e.g., scalp, genitals, palms/soles, nails, face), is refractory to prior treatment with topicals, is associated with psoriatic arthritis, or simply involves a greatly negative quality of life. The truth is most dermatologists often use biologic/systemic therapy for patients with lower severities (BSA<10%) than what would be allowable in a clinical trial for these drugs. This is evidence of a disconnect between trial criteria and clinical practice, i.e., patient- and study-defined severity often do not agree.

What do your findings change in terms of care decisions and trial criteria?

Dr. Strober: The upshot of the above is patients in need of systemic/biologic agents are not studied in clinical trials, and therefore safety and efficacy data from lower BSA populations are lacking. Further, national health systems and private payers deny reimbursement for patients in need. Ultimately, because of this environment, dermatology providers often undertreat patients. The criteria from our Delphi exercise are realistic, expanding the appropriateness of treating with systemic/biologic therapy if patients are less than 10 percent BSA if they either 1.) failed topical therapy or 2.) have psoriasis involving the “special areas.” This brings treatment more in line with the real-world paradigm. If payers (and companies studying newer drugs) would adopt these criteria, then stringent cutoff criteria would be rendered obsolete, and patients truly in need would gain greater access to medications that are both safe and very effective.

How are these being adopted?

Dr. Strober: As they are “real” or in line with real-world practice habits, the criteria are already adopted by many dermatologists. We are actually planning studies to prove this point. That said, not all dermatologists adhere to these criteria, primarily because payers currently don’t universally recognize them, and fighting payers is an expensive proposition.

Have you stopped using the terms mild, moderate, and severe in practice?

Dr. Strober: I have. It’s either topical- or systemic therapy-appropriate. Patients need no convincing, as to them it is not about BSA cutoffs, but the quality of life hit that their psoriasis creates. Patients are often in search of dermatologists looking to view their condition from the perspective of how the disease affects them, regardless of BSA. For example, someone whose entire scalp is covered with thick, topical treatment-resistant psoriasis might only have five percent of their BSA affected, but they need a systemic/biologic therapy, and they know it. The greater sell is to some reluctant providers and to payers and regulators.

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