Localization of Treatment-resistant Areas in Patients With Psoriasis on Biologics

K.F. Hjuler; L. Iversen; M.K. Rasmussen; K. Kofoed; L. Skov; C. Zachariae


The British Journal of Dermatology. 2019;181(2):332-337. 

In This Article

Abstract and Introduction


Background: Traditionally, psoriasis in certain body sites such as the scalp, nails, palms, soles and intertriginous areas has been acknowledged as difficult to treat.

Objectives: To investigate the body location of treatment-resistant psoriasis in patients treated with biologic agents in real-world clinical practice, and to study the association between localization and quality of life.

Methods: This was an observational, noninterventional, study. We investigated the skin and/or nail location of treatment-resistant psoriasis in patients with moderate-to-severe psoriasis treated for > 6 months with biologic agents. A partial or good response to treatment was defined as having a Psoriasis Area and Severity Index (PASI) score ≥ 1 and ≤ 5. Experienced PASI assessors used a uniform data collection form in which the body area was divided into 26 regions and 20 nails.

Results: We included 146 patients with chronic plaque-type psoriasis (109 men, 74·7%, mean ± SD age 49·8 ± 13·7 years), with a median PASI score of 2·4 (interquartile range 1·2–3·2). The median PASI reduction from treatment initiation was 86·1% (interquartile range 78·1–91·3). The most common site of recalcitrant psoriasis was the anterior lower leg [49·3%; 95% confidence interval (CI) 41·2–57·4]. Further common sites of recalcitrant psoriasis were the posterior lower leg (24·7%; 95% CI 17·7–31·6), elbow (35·6%; 95% CI 27·8–43·4) and the scalp (19·2%; 95% CI 12·8–25·6%). No association between Dermatology Life Quality Index and specific areas of recalcitrant psoriasis were observed.

Conclusions: In real-world clinical practice, the most common sites of recalcitrant psoriasis in patients treated with biologic agents are the anterior lower leg, posterior lower leg and elbows. Recalcitrant psoriasis in no specific area caused a greater impact on quality of life than any other area.


Psoriasis is a common, chronic skin disease affecting approximately 2–4% of the Western population. Plaque-type psoriasis (henceforth 'psoriasis') is the most common variant and accounts for 85–90% of cases.[1] The sites of predilection are the extensor sides of the forearms, shins, elbows, knees, buttocks, scalp and the periumbilical area. However, all areas of the skin can be affected. Involvement of the scalp is common and may affect up to 80% of patients to a variable extent.[2] Nail psoriasis is observed in about 50% of patients.[1] Other site-specific variants are inverse psoriasis localized to the flexural/intertriginous areas, and sebopsoriasis localized to the eyebrows, nasolabial folds, and postauricular and presternal areas. Traditionally, psoriasis at certain body sites has been acknowledged as difficult-to-treat variants. Such locations are the scalp, nails, palms, soles and intertriginous areas.[3,4]

During the last decade, several highly effective systemic agents have been approved for the treatment of psoriasis. Despite the availability of these novel agents, the same entities are still considered difficult-to-treat areas.[5,6] In the literature, we cannot find supporting evidence that these areas are difficult or recalcitrant to treat with the new biologic agents. To our knowledge, no published studies have examined the location of recalcitrant psoriasis in patients treated with biologic agents.

The aim of this study was to investigate the site of treatment-refractory psoriasis in patients treated with biologic agents or apremilast and thereby obtain evidence for true 'difficult-to-treat' areas in a real-life setting. Furthermore, we wanted to study whether these difficult-to-treat areas had an influence on the quality of life in patients with psoriasis. Therefore, the association between the Dermatology Life Quality Index (DLQI) levels and body locations of recalcitrant psoriasis in patients with low absolute Psoriasis Area and Severity Index (PASI) scores were studied.