Methotrexate in psoriasis: 26 years' experience with low-dose long-term treatment

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 psorias is, erythrodermic, pustular and arthropathic forms, were treated with low-d ose 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 po or in 6% of subjects; 61% experienced side-effects, most frequently due to liver function abnormalities, bone marrow suppression, nausea, gastric comp laints and hair loss. In 20% of cases the subjects were forced to discontin ue therapy; 9% refused therapy due to physical and psychological discomfort , 2% wanted to become pregnant, 16% were lost to follow-up, 6% died from mu ltimorbidity and old age. Three subjects (2%) developed cancer of the lung, breast or cervix uteri, possibly in relation to long-term MTX treatment. A ltogether there were no deaths or life-threatening side-effects attributabl e to MTX treatment, and no cases of progressive liver cirrhosis apart from two extensive skin necroses due to overdosage (misunderstanding, suicidal a ttempt) that were treated successfully with citrovorum factor. Conclusion Low-dose MTX (<15-20 mg/week) is an effective therapy for extens ive and severe forms of psoriasis if patients are selected carefully and mo nitored regularly, particularly with respect to liver and bone marrow toxic ity. This helps to reduce severe side-effects even during long-term treatme nt. Drug interactions must be avoided. MTX therapy according to the guideli nes is relatively safe and still has a place in the systemic treatment of p soriasis with 40 years of experience and an acceptable safety record.