Objective To evaluate the efficacy, safety and side-effects of methotrexate (MTX) in psoriasis.
Design A 26-year retrospective study.
Setting Department of Dermatology, Leipzig University, Leipzig, Germany.
Patients One hundred and fifty-seven patients with extensive plaque psoriasis, erythrodermic, pustular and arthropathic forms, were treated with low-dose methotrexate (15–20 mg maximum weekly dosage [Weinstein schedule]), the majority for long-term periods. The mean cumulative dose was 3394 mg, the mean duration 237 weeks.
Results The effect of MTX treatment was good in 76%, moderate in 18% and poor in 6% of subjects; 61% experienced side-effects, most frequently due to liver function abnormalities, bone marrow suppression, nausea, gastric complaints and hair loss. In 20% of cases the subjects were forced to discontinue therapy; 9% refused therapy due to physical and psychological discomfort, 2% wanted to become pregnant, 16% were lost to follow-up, 6% died from multimorbidity and old age. Three subjects (2%) developed cancer of the lung, breast or cervix uteri, possibly in relation to long-term MTX treatment. Altogether there were no deaths or life-threatening side-effects attributable to MTX treatment, and no cases of progressive liver cirrhosis apart from two extensive skin necroses due to overdosage (misunderstanding, suicidal attempt) that were treated successfully with citrovorum factor.
Conclusion Low-dose MTX (<15–20 mg/week) is an effective therapy for extensive and severe forms of psoriasis if patients are selected carefully and monitored regularly, particularly with respect to liver and bone marrow toxicity. This helps to reduce severe side-effects even during long-term treatment. Drug interactions must be avoided. MTX therapy according to the guidelines is relatively safe and still has a place in the systemic treatment of psoriasis with 40 years of experience and an acceptable safety record.