4-week methotrexate predicts long-term response in patients with psoriasis
Researchers have recently developed and validated a prediction rule to identify patients with moderate-to-severe psoriasis who are not likely to respond adequately to methotrexate, reports a study. The rule indicates that 4 weeks of methotrexate may be enough to predict long-term response with limited safety risk.
Patient-level data from the CHAMPION trial (n=100) were obtained to develop a prediction model for week 16 PASI75 (75-percent reduction from baseline Psoriasis Area and Severity Index score), with the use of patient baseline characteristics and week 4 PASI25.
Researchers developed the prediction rule based on sensitivity and specificity, and validated this in terms of week 16 PASI75 response in an independent validation sample from the M10-255 trial (n=163).
Patient response with methotrexate at week 16 was strongly predicted by PASI25 achievement at week 4 (odds ratio, 8.917). Patients were recommended to stop taking methotrexate when they have a predicted response probability <30 percent.
The rate of week 16 PASI75 response was 65.8 percent for patients recommended to continue methotrexate and 21.1 percent for those recommended to discontinue the medication.
The study was limited by the exclusion of patients previously treated with biologics in the CHAMPION trial and the absence of restrictions in the M10-255 trial.
“Most methotrexate-treated psoriasis patients do not achieve a long-term PASI75 response,” researchers said. “Indications of nonresponse can be apparent after only 4 weeks of treatment.”
In a subanalysis of the CHAMPION trial, nearly all week-16 PASI75 responders achieved a PASI50 response at week 8 or 12, with maximum methotrexate dosages of 15 or 20 mg per week, respectively. Researchers said that week 12 might be a suitable time to discontinue methotrexate treatment in patients who were not achieving good responses. [Br J Dermatol 2011;165:399-406]