Azathioprine in severe adult atopic dermatitis: a double-blind, placebo-controlled, crossover trial

Background There is a limited range of treatments for severe atopic dermatitis (AD). Azathioprine has often been used but there has been no randomized controlled trial of this drug to confirm its efficacy in AD. Objectives To establish or refute the efficacy of azathioprine in severe AD. To investigate the safety and tolerability of azathioprine in this patient population. Methods We performed a double-blind, randomized, placebo-controlled, crossover trial of azathioprine in adult patients with severe AD. Each treatment period was of 3 months' duration. Treatments were azathioprine 2.5 mg kg(-1) day(-1) and matched placebo. Disease activity was monitored using the SASSAD sign score. In addition, severity of pruritus, sleep disturbance and disruption of work/daytime activity were monitored using visual analogue scales. Adverse events were recorded and haematological and biochemical monitoring was performed. Results Thirty-seven subjects were enrolled, mean age 38 years (range 17-73). Sixteen were withdrawn, 12 during azathioprine treatment and four during placebo treatment. The SASSAD score fell by 26% during treatment with azathioprine vs. 3% on placebo (P < 0.01). Pruritus, sleep disturbance and disruption of work/daytime activity all improved significantly on active treatment but not on placebo. The difference in mean improvement between azathioprine and placebo was significant for disruption of work/daytime activity (P < 0.02) but not for pruritus or sleep disturbance. Gastrointestinal disturbances were reported by 14 patients during azathioprine treatment and four were withdrawn as a result of severe nausea and vomiting. Leukopenia was observed in two patients and deranged liver enzymes in eight during treatment with azathioprine. Conclusions Azathioprine is an effective and useful drug in severe AD although it is not always well-tolerated. Monitoring of the full blood count and liver enzymes is advisable during treatment.