Assessment of oral methotrexate intolerance in Japanese adult patients with rheumatoid arthritis

AimThe objective of this study was to assess the gastrointestinal side (GI) effects of oral methotrexate (MTX) in Japanese adult patients with rheumatoid arthritis (RA). MethodsIn this single-center retrospective study, 112 Japanese adult patients (over 18 years old) with RA were examined by Methotrexate Intolerance and Severity assessment in Adults (MISA) questionnaire. ResultsForty-five (40.2%) of patients were MTX intolerant (MISA score >= 1). Twelve patients (11.2%) were moderate-to-severe MTX intolerant (MISA cross-product score >= 4). The most common GI side effects of MTX were gastric discomfort (26.8%), followed by loss of appetite or dysgeusia (14.3%), fatigue and lethargy (12.5%), and nausea (10.7%). ConclusionsJapanese adult patients with RA showed a high prevalence of MTX intolerance even in low-dose oral MTX. The MISA questionnaire was practical for finding patients with MTX intolerance.