PURPOSE: Psoriasis is a chronic inflammatory skin disease that is associated with considerable psychosocial morbidity and affects approximately 2% of the general population. The purpose of this study was to characterise patient preferences towards the attributes of treatments for psoriasis and examine trade-offs between the risks and benefits of treatments.

METHODS: Psoriasis patients were recruited from three hospital dermatology clinics in England. Preferences for the attributes of time to moderate improvement of psoriasis, relapse of symptoms and treatment-related risks of experiencing skin irritation, high blood pressure, liver damage and skin cancer were collected using a self-completed questionnaire containing a stated preference discrete choice experiment (DCE). Experimental design theory was used to identify 16 pair-wise treatment choices in which levels of attributes were varied independently. For each choice set, the participants were asked to select which treatment scenario they would prefer for the management of their psoriasis. Data was analysed using a linear additive random effects probit model using STATA v8.0.

RESULTS: 126 psoriasis patients completed the DCE. Sixty-four (51%) were female and the mean age of all participants was 47 years. The coefficients for all six treatment attributes were statistically significant (p<0.01), indicating that they were all important factors influencing patients' choice of treatment. Comparing the coefficients of the different side-effects indicated that the patients considered the long-term risks of experiencing skin cancer and liver damage to be the most important adverse events influencing their choice of treatment, followed by the risk of experiencing high blood pressure. The risk of skin cancer was considered to be least important. The patients also prioritised time to moderate improvement in their condition over time to relapse.

CONCLUSIONS: This study provides novel insights into the trade-offs that patients undertake when using treatments to manage their psoriasis. Given the well recognised problems with adherence to treatment, it is important to understand the preferences of patients with psoriasis in relation to treatment options.