Dermatologists’ Perspectives on Defining Moderate Psoriasis: The Canadian Moderate Psoriasis Survey

February 2021 | Volume 20 | Issue 2 | Original Article | 126 | Copyright © February 2021

Published online January 8, 2021

Melinda Gooderham MD MSc,a-c Kim Papp MD PhD,b Lorne Albrecht MD,b,d,e Parbeer Grewal MDb,f,g Anne-Julie Gaudreau, MSch

aSKiN Centre for Dermatology, ON, Canada
bProbity Medical Research, Inc.,Waterloo, ON, Canada
cQueen’s University, Peterborough, ON, Canada
dEnverus Medical, Surrey, BC, Canada
eUniversity of British Columbia,Vancouver, BC, Canada
fStratica Medical, Edmonton, AB, Canada
gUniversity of Alberta, Edmonton, AB, Canada
hAmgen Inc., Mississauga, ON, Canada

Background: Psoriasis is commonly classified as either mild or moderate to severe, without specific parameters to differentiate moderate versus severe disease. This may lead to patients with moderate psoriasis being underrecognized and undertreated.
Objective: An online survey was conducted to assess Canadian dermatologists’ perspectives on the definition and treatment of psoriasis.
Method: Dermatologists included in the survey were regional and national leaders with expertise in psoriasis. Questions were developed based on feedback from a steering committee of Canadian dermatologists.
Results: Of 88 dermatologists contacted, 69 responded; 42.0% were in practice for >20 years. Most dermatologists reported using the percentage of psoriasis-affected body surface area (BSA) to describe disease severity (90.8% for moderate and 87.5% for severe psoriasis). The lower and upper median cutoffs for moderate psoriasis were reported as 5.0% and 10.0% for BSA and 7.0 and 11.5 for the Dermatology Life Quality Index. Most dermatologists also consider psoriasis location (eg, palms, scalp, genital area, face) as an important indicator of disease severity. The majority of Canadian dermatologists (87.5%) identified access to treatment as one of the biggest challenges for patients with moderate psoriasis. Most dermatologists estimated that ≤40% of their patients with moderate plaque psoriasis were being treated with traditional oral systemics, targeted oral systemics, or biologics.
Conclusions: This is the first survey of Canadian dermatologists on moderate psoriasis. Efforts are needed to implement a clinically useful definition of moderate plaque psoriasis to improve patient care and to raise awareness of the definition among regulatory agencies and reimbursement authorities.

J Drugs Dermatol. 20(2):126-132. doi:10.36849/JDD.2021.5531


Psoriasis is a chronic inflammatory skin disorder that impairs physical and psychosocial functioning.1-3 In addition to work impairment, patients with psoriasis report that they experience frequent negative emotions and difficulties with social interactions due to this highly visible disease.2 Psoriasis is estimated to affect 1% to 3% of Canadians, although its prevalence has been reported to be as high as 4.7% in some instances.4

Psoriasis Assessment Tools
The severity of psoriasis varies depending on the patient and location of the affected area, which commonly includes the scalp, elbows and knees, and peri-umbilical and peri-anal regions.3,5 Several assessment tools exist to quantify the impact of psoriasis, including the Psoriasis Area and Severity Index (PASI), psoriasis-involved body surface area (BSA), Dermatology Life Quality Index (DLQI), and Physician Global Assessment (PGA).6 According to Finlay’s “rule of tens,” a practical concept used to guide decision-making in clinical practice settings, severe psoriasis refers to patients with a BSA >10%, PASI score >10, or DLQI score >10.7 Finlay’s proposal is comparable with that of the National Psoriasis Foundation, which defines mild psoriasis as BSA <3%, moderate psoriasis as BSA 3% to 10%, and severe psoriasis as BSA >10%.8

Defining Moderate Psoriasis
Despite these efforts to classify psoriasis disease severity, psoriasis categories are often combined or collapsed for