Validation of Methotrexate Intolerance Severity Score (MISS) Questionnaire to Measure Methotrexate Intolerance among Rheumatoid Arthritis Egyptian Patients

Abstract Background Rheumatoid arthritis (RA) is a systemic, autoimmune inflammatory disease whose manifestations occur in synovial joints and in different organs and systems, causing chronic pain, bone erosion and progressive disability. Methotrexate (MTX) is the most important disease modifying antirheumatic drug in the treatment of RA. Objective To validate MISS questionnaire in Egyptian RA patients as a tool for early detection of MTX intolerance and change of treatment at an early stage to prevent disease progression. Patients and Methods This study is a Cross Sectional Study Settled in Physical Medicine, Rheumatology and Rehabilitation (PRR) outpatient clinic of Ain Shams University hospital. The Arabic MISS was used in this survey. Statistical analyses were performed to understand associations between different MTX-intolerant and MTX-tolerant patients. Results A total of 80 patients were involved in this study. Of those, 67 (83.8%) were females with a mean disease duration of 6.9 ± 6.1 years. Intolerant patients had a higher patient global assessment (P = 0.036), Disease activity score 28 (P=.000) and Health assessment questionnaire score (P = 0.007) compared to those in tolerant patients. MISS questionnaire helps us to detect early MTX intolerance and actually we found high prevalence in Egyptian RA patients as MTX intolerance was observed in 48 (60%) patients, our finding revealed that behavioral intolerance is the predominant factor that directs MTX intolerance. In our study, the reliability of MISS questionnaire is measured by Cronbach’s alpha coefficient and it is 0.809 suggesting a good internal consistency of the survey items. Conclusion MISS questionnaire has good predictive ability to detect MTX intolerance.it gives great importance to anticipatory and associative symptoms. MTX intolerance is common; present in more than half of RA patients. Behavioral component is the main driver of intolerance.