Psoriasis: New disease severity classification

During a session organised by the International Psoriasis Council (IPC), Prof. Lone Skov (University of Copenhagen, Denmark), co-chair of the Psoriasis Severity Classification working group, presented the new disease classification [1]. The consensus document has recently been published [2].

Founded in 2004, the IPC (www.psoriasiscouncil.org/) is a dermatologist-led, voluntary, global, non-profit organisation with a network of >100 psoriasis experts, thought leaders, and professionals, dedicated to improving patient care around the globe. Their mission is to improve the care of people with psoriasis worldwide through research, education, and advocacy.

Previous classification

To define whether or not the patient needed systemic treatment, a group of dermatologists from Europe graded psoriasis into mild and moderate-to-severe disease in 2011 [3]. Mild disease was defined as BSA ≤10, Psoriasis Area and Severity Index (PASI) ≤10, and Dermatology Life Quality Index (DLQI) ≤10, while moderate-to-severe psoriasis was defined as BSA >10 or PASI >10 and DLQI >10. Special clinical situations may change mild psoriasis to moderate-to-severe, including involvement of visible areas or severe nail involvement. However, there is no consensus on this classification because it has some limitations. Firstly, PASI and DLQI are often not used in clinical practice because they are time-consuming to measure. Furthermore, this classification does not consider the presence of areas difficult to treat with topical or special areas.

New IPC classification

Because of these limitations of the 2011 classification, the IPC recently aimed to redefine disease severity classification using a Delphi process [2]. According to the new disease severity classification, patients with psoriasis should be classified as either candidates for topical therapy or candidates for systemic therapy. The latter are patients who meet ≥1 of the following criteria: BSA >10, disease involving special areas, specifically areas that are difficult to treat with topical therapy (e.g. face, palms, soles, genitals, scalp, and nails), and failure of topical therapy.

This new classification has some limitations. Firstly, no patient-reported outcomes and no definition of failure of topical therapy are incorporated [1]. Moreover, no general dermatologists nor patients were involved in the process. Strengths include that the recommendations were patient-oriented and developed by an international group of dermatologists with expertise in psoriasis from all over the world. In addition, the proposed disease classification is simple, practical, and easy to use in daily practice. Based on this definition, whether a patient is a candidate for topical or systemic treatment is easily decided.

Future aims include demonstrating the new classification in real-world practice. “We should focus on educating regulatory bodies, clinicians, and patients on the new classification,” concluded Prof. Skov.

1. Skov L. IPC’s disease severity classification: What it means in the clinic. 6^th World Psoriasis & Psoriatic Arthritis Conference, 30 June–3 July 2021.
2. Strober B, et al. J Am Acad Dermatol. 2020;82:117-–22.
3. Mrowietz U, et al. Arch Dermatol Res. 2011;303:1–10.

 

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Posted on 17 September 202120 September 2021