aMedical College of Wisconsin, Milwaukee, WisconsinbAnalysis Group Inc, Boston, MassachusettscAbbVie Inc, North Chicago, IllinoisdFort HealthCare, Fort Atkinson, Wisconsin
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BackgroundMost methotrexate-treated psoriasis patients do not achieve a long-term PASI75 (75% reduction from baseline Psoriasis Area and Severity Index score) response. Indications of nonresponse can be apparent after only 4 weeks of treatment.ObjectiveTo develop a prediction rule to identify patients unlikely to respond adequately to methotrexate.MethodsPatient-level data from CHAMPION (NCT00235820, N = 110) was used to construct a prediction model for week 16 PASI75 by using patient baseline characteristics and week 4 PASI25. A prediction rule was determined on the basis of the sensitivity and specificity and validated in terms of week 16 PASI75 response in an independent validation sample from trial M10-255 (NCT00679731, N = 163).ResultsPASI25 achievement at week 4 (odds ratio = 8.917) was highly predictive of response with methotrexate at week 16. Patients with a predicted response probability <30% were recommended to discontinue methotrexate. The rates of week 16 PASI75 response were 65.8% and 21.1% (P < .001) for patients recommended to continue and discontinue methotrexate, respectively.LimitationsThe CHAMPION trial excluded patients previously treated with biologics, and the M10-255 trial had no restrictions.ConclusionA prediction rule was developed and validated to identify patients unlikely to respond adequately to methotrexate. The rule indicates that 4 weeks of methotrexate might be sufficient to predict long-term response with limited safety risk.