Topical Treatments for Chronic Plaque Psoriasis

Background: Chronic plaque psoriasis is the most common type of psoriasis and is characterized by redness, thickness, and scaling. First-line management of chronic plaque psoriasis is with topical treatments, including vitamin D analogues, topical corticosteroids, tar-based preparations, dithranol, salicylic acid, and topical retinoids. Objectives: To compare the effectiveness, tolerability, and safety of topical treatments for chronic plaque psoriasis with placebo; to compare vitamin D analogues with other topical treatments. Search Strategy: The Cochrane Skin Group's Trials Register was searched (December 2004). To update an unpublished 2002 review, the researchers also searched CENTRAL in the Cochrane Library (2005; Issue 1); Medline (to February 2005); EMBASE (to August 2005); Science Citation Index (to 2005); Biosis (to 2005); Dissertation Abstracts (all publication years); Inside Conferences (all publication years); SIGLE (to 2005); National Research Register (all projects with a start date of 2001 to 2005); and metaRegister of Current Controlled Trials. Selection Criteria: Randomized trials comparing treatments with placebo or with vitamin D analogues in persons with chronic plaque psoriasis. Data Collection and Analysis: One author extracted study data and assessed study quality. A second author checked these data. Researchers routinely contacted trial lists and companies for missing data. They extracted data on withdrawals and adverse effects. Main Results: The review included 131 randomized controlled trials with 21,448 participants. Vitamin D was significantly more effective than placebo, although there was a wide variation in effect size, with the standardized mean difference (SMD) ranging from -0.82 (95% confidence interval [CI], -1.34 to -0.29) to -1.90 (95% CI, -2.09 to -1.71). With one exception, all corticosteroids performed better than placebo, with potent corticosteroids (SMD = -0.95; 95% CI, -1.11 to -0.80; I(2) [heterogeneity statistic] = 61.1 percent; 17 studies; 2,386 participants) having smaller benefits than very potent corticosteroids (SMD=-1.29; 95% CI, -1.45 to -1.13; I(2) = 53.2 percent; 11 studies; 1,571 participants). Dithranol and tazarotene performed better than placebo. Head-to-head comparisons of vitamin D against potent or very potent corticosteroids found no significant differences. However, combined treatment with vitamin D/corticosteroid performed significantly better than either vitamin D or corticosteroid alone. Vitamin D performed better than coal tar, but findings relative to dithranol were mixed. Potent corticosteroids were less likely than vitamin D to cause local adverse effects. No comparison of topical agents found a significant difference in systemic adverse effects. Authors' Conclusions: Corticosteroids perform as well as vitamin D analogues and are associated with a lower incidence of local adverse effects. Further research is required to inform long-term maintenance treatment.