Factors predicting the response to low-dose methotrexate therapy in patients with rheumatoid arthritis: A better response in male patients

Methotrexate (MTX) is the most commonly used disease-modifying antirheumatic drug (DMARD) throughout the world. In Japan, MTX is recommended by the Japanese Ministry of Health, Labour, and Welfare to be given as the second or third DMARD and at a dosage of no more than 8 mg/week. We analyzed the efficacy of MTX in Japanese patients with RA in order to determine whether it is comparable to that in Western countries, where 15-20 mg/week of MTX is used, as well as to elucidate the factors associated with the favorable response to MTX. Around 8 mg/week of MTX was effective in half of the RA patients in the current study, and male sex was the only factor associated with a good response to MTX from a multivariate regression model analysis. Some of the patients who had a poor response to MTX showed an improvement with the addition of bucillamine or prednisolone. For the remaining patients, an increase in the MTX dosage to more than 8 mg/week or the use of biologics such as the anti-tumor necrosis factor (TNF)-α monoclonal antibody may be required.