Observations of psoriasis in the absence of therapeutic intervention identifies two unappreciated morphologic variants, thin-plaque and thick-plaque psoriasis, and their associated phenotypes.

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.

Impact of obesity and smoking on psoriasis presentation and management.

OBJECTIVE: To study the impact of obesity and smoking on psoriasis. DESIGN: Cross-sectional study. SETTING: University of Utah Department of Dermatology clinics. PATIENTS: A case series of patients with psoriasis enrolled in the prospective Utah Psoriasis Initiative (UPI) (which carefully performs phenotyping of patients with psoriasis) was compared with 3 population databases: the Behavioral Risk Factor Surveillance System of the Utah population, the 1998 patient-member survey from the National Psoriasis Foundation, and 500 adult patients who attend our clinics and do not have psoriasis (non-psoriatic population). RESULTS: The prevalence of obesity in patients within the UPI population was higher than that in the general Utah population (34% vs 18%; P<.001) and higher than that in the non-psoriatic population attending our clinics. Assessment of body image perception with a standardized diagram in the UPI group resulted in the median body image score of normal weight at 18 years of age and the onset of psoriasis, but it changed to overweight at the time of enrollment in the UPI. Thus, obesity appears to be the consequence of psoriasis and not a risk factor for onset of disease. We did not observe an increased risk for psoriatic arthritis in patients with obesity; furthermore, obesity did not positively or negatively affect the response or the adverse effects of topical corticosteroids, light-based treatments, and systemic medications. The prevalence of smoking in the UPI population was higher than in the general Utah population (37% vs 13%; P<.001) and higher than in the non-psoriatic population (37% vs 25%; P<.001). We found a higher prevalence of smokers in the obese population within the UPI than in the obese population within the Utah population (25% vs 9%; P<.001). CONCLUSIONS: Patients with psoriasis attending the University of Utah Dermatology Clinics were more likely to be obese and to smoke compared with non-psoriatic patients and more likely to be obese compared with other large cohorts with psoriasis. Smoking appears to have a role in the onset of psoriasis, but obesity does not. The high prevalence of obesity and smoking in a psoriasis cohort has not been previously noted; if confirmed, it supports the prediction that a significant portion of patients with psoriasis will have the comorbid conditions and public health issues of those with obesity and smoke.