Figure 1Terms Used in Evaluating Plaque Psoriasis

BSA = body surface area; DLQI = Dermatology Life Quality Index; PASI = Psoriasis Area Severity Index; QoL = quality of life.

TermDefinitions used in clinical trialsDefinition for clinical practice, as applied in these Guidelines
Measures of disease severity
Mild plaque psoriasisNot commonly defined; the US National Psoriasis Foundation suggests BSA = 5% as an upper limit for mild disease12Disease with a minimal impact on the patient’s QoL; patient can achieve an acceptable level of symptomatic control by routine skin care measures and/or topical therapy
Moderate plaque psoriasis

The lower limit of moderate to severe psoriasis may be set at PASI = 813,14 or, in trials of biologics, typically higher

Several biologics trials have used criteria as stringent as PASI ≥ 12 and BSA ≥ 10% to define the lower limit of “moderate to severe” psoriasis,15,16 although the same limits have also been used to define “severe” psoriasis17

Disease that cannot be, or would not be expected to be, controlled to an acceptable degree by routine skin care measures and/or disease that significantly affects the patient’s QoL, either because of the extent of the disease, the physical discomfort it causes (pain or pruritus), or the location where the disease manifests (e.g., the face, hands, feet, or genitals)
Severe plaque psoriasis

The Rule of Tens requires PASI ≥ 10 or DLQI ≥ 10 or BSA ≥ 10%18

In some phototherapy trials, BSA ≥ 20% is the lower limit of severe disease19,20

Disease that cannot be, or would not be expected to be, satisfactorily controlled by topical therapy and that causes severe degradation of the patient’s QoL

Source: Papp K, Gulliver W, Lynde C, Poulin Y, Ashkenas J, Canadian Psoriasis Guidelines Committee. Canadian Guidelines for the Management of Plaque Psoriasis: Overview. J Cutan Med Surg. 2011;15(4):210–219 [PubMed: 21781627].

Reprinted with a permission of the author. Source: Canadian Guidelines for the Management of Plaque Psoriasis.4.

From: Introduction

Cover of Clinical Review Report: Halobetasol Propionate and Tazarotene (Duobrii)
Clinical Review Report: Halobetasol Propionate and Tazarotene (Duobrii): (Bausch Health, Canada Inc.): Indication: Psoriasis, moderate-to-severe plaque [Internet].
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