¹Department of Dermatology, University of Utah School of Medicine, Salt Lake City, Utah, USA

Correspondence: Dr Gerald G. Krueger, Department of Dermatology, University of Utah Health Sciences Center, 4B454 School of Medicine, 30 North 1900 East, Salt Lake City, Utah 84132-2409, USA. E-mail: krueger@derm.med.utah.edu

²Current address: Department of Dermatology, Medical University of South Carolina, Charleston, South Carolina, USA.

³Current address: Department of Dermatology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.

Received 31 August 2005; Revised 10 April 2006; Accepted 9 May 2006; Published online 20 July 2006.

Abstract

Psoriatic plaque thickness is a clinical measure of psoriasis severity. We have observed that patients tend to revert to a baseline thickness of psoriatic plaques when in an untreated state, and hypothesized that other features of psoriasis could associate with this trait. Data prospectively collected on 500 participants in the Utah Psoriasis Initiative were used for the study. In response to a question assessing plaque thickness when disease was at its worst, 144 (28.8%) reported thick plaques, 123 (24.6%) reported thin plaques, and 233 (46.6%) reported intermediate thickness. For patients with "worst-ever" disease at enrollment (n=122), there was significant correlation of thickness between assessment by the patient and the physician (r=0.448, P-value 0.01). Thick plaques associated with male gender, increased body mass index, nail disease, psoriatic arthritis, larger plaques, more body sites, and greater total body surface area affected. Thin plaques associated with eczema, guttate psoriasis, and skin cancer. We suggest that this is preliminary evidence that plaque thickness is an easily measured trait that associates with other clinical features of psoriasis, and that stratification on this phenotype may be useful in further defining the genetic basis of this disease.