Comparison of Characteristics of Methotrexate Tolerant and Intolerant Patients Having Rheumatoid Arthritis

Objectives: To compare the characteristics of methotrexate-tolerant and intolerant patients having rheumatoid arthritis. To determine the association of methotrexate intolerance with the patient and disease-related factors. Method: This cross-sectional study was carried out at the rheumatology department of Combined Military Hospital Lahore from 31st April to 30th June 2022. It included 181 rheumatoid arthritis (RA) patients using methotrexate (MTX) for > 3 months. Patient demographic variables, disease duration and activity, and information regarding MTX intake were recorded. English methotrexate intolerance severity score (MISS) questionnaire was used to calculate MTX intolerance. Different variables were compared between methotrexate-tolerant and intolerant patients. Association of age, disease duration, and activity, MTX route/dose with MTX intolerance was determined. Results: The majority of patients were females 140(77%). The median disease duration was 6(1-40) years. MTX intolerance was found in 48(26.5%) of RA patients. Intolerant patients had a higher disease activity score (DAS 28>5.1 in 20.8 vs 3.8%; P = 0.002) and longer duration of MTX intake in months (23.5 vs 12; p=0.018) compared to tolerant patients. Additionally, MTX intolerance was associated with younger age, longer disease duration and higher MTX dose>10mg/wk (P=0.007, P=0.025, P=0.050). There was no significant difference between the two groups in gender, marital status, education, and use of other DMARDs or steroids. (P >0.05). Conclusion: There was a significant association between age, disease duration, and MTX dose with MTX intolerance. We also noted a significant association between disease activity and route of intake with MTX intolerance but this was lost when adjusted for multiple confounders.