Summary Background This study was part of a large national cost‐effectiveness analysis, and was funded by the National Fund for Investigational Medicine of the Health Care Insurance Board. Objectives To compare the costs of treatment of moderate to severe psoriasis by dithranol short contact therapy in a care instruction programme (short contact therapy) with ultraviolet B phototherapy (UVB) and inpatient dithranol treatment (inpatient treatment), and relate these costs to treatment effectiveness. Methods An open randomized controlled multicentre study was performed. The costs (both medical and non‐medical) were calculated for the following periods: during treatment, per month during remission, after a relapse, and following an unsuccessful treatment. The effectiveness measures were the clinical response rate and the number of clearance days during follow‐up. Results The data from 216 patients were analysed. The mean overall costs per patient during treatment were €1641, €1258 and €7706 for short contact treatment, UVB and inpatient treatment, respectively. During the clearance period the mean costs per month per patient were €19, €5 and €25, respectively. The clinical response rates were 57%, 57% and 85%, respectively. The mean number of clearance‐days after short contact treatment was 160 [median 119; interquartile range (0–357)], which was not significantly different from the other two strategies: 211 clearance‐days after inpatienttreatment [241 (99–350)] and 136 clearance‐days after UVB [81 (0–266)]. Conclusion Short contact treatment is an attractive alternative for patients with moderate to severe psoriasis currently treated by inpatient treatment, as the costs of short contact treatment were significantly lower and the number of clearance days was comparable. Considering the higher costs, short contact treatment is not a first choice treatment when compared with UVB.

The hypothesis that calcipotriol ointment might be at least as effective as dithranol cream in the day-care setting could not be proven in the present study. Whereas calcipotriol has become a mainstay in the routine outpatient treatment of psoriasis not requiring a day-care setting, dithranol treatment, being difficult as a routine outpatient therapy, has increased efficacy and improved tolerability if the treatment is carried out in a day-care setting.