Cost-effectiveness analysis of topical calcipotriol versus short-contact dithranol - In the treatment of mild to moderate plaque psoriasis

Objective: To examine the relative cost effectiveness of topical calcipotri ol and short-contact dithranol in the treatment of mild to moderate plaque psoriasis. Design and setting: This was a modelling study from the perspective of the UK National Wealth Service as payer. Methods: The interventions were compared using 2 decision-analytic models: one using a short term horizon (12 weeks) and the other using a longer term horizon (up to 1 year). Clinical success of treatment and relapse rates we re obtained from the results of randomised controlled trials. Main outcome measures and results: The outcome measure used was the degree of improvement in psoriasis as judged by the patient. In the short term com parison, calcipotriol was the most effective treatment (60.8% success), but it was also the most expensive (pound 96.03; 2000 values). The incremental cost per success was pound 77.50 using a 12-week course of calcipotriol co mpared with short-contact dithranol. Over the long term horizon, first-line treatment with calcipotriol still had the highest expected cost per succes sful treatment (pound 164.91), but the incremental cost using this strategy was pound 38.66 compared with short-contact dithranol. In terms of cost pe r successful day's treatment (i.e. the cost for a day in which the patient reported a marked improvement or cleared lesions), the cost of each additio nal successful day's treatment was pound 19.93 when using calcipotriol as f irst-line treatment rather than short-contact dithranol. Conclusion: The combination of differences in drug acquisition costs and re lapse rates can lead to large differences in the comparative cost effective ness of topical treatments for plaque psoriasis. From the perspective of th e prescriber, the results of this analysis suggest that selecting short-con tact dithranol as first-line treatment was the most cost-effective strategy .