To evaluate toxicity profiles in patients with rheumatoid arthritis (RA) treated either according to an intensive or a conventional treatment strategy approach with methotrexate (MTX) and to study factors associated with MTX-related toxicity.
Data were used from the Computer-Assisted Management in Early Rheumatoid Arthritis (CAMERA) study, in which clinical efficacy of an intensive treatment strategy with MTX was more beneficial than a conventional treatment strategy approach. In this study, data on adverse events (AEs) were compared between the two strategy groups. Logistic regression analyses were used to identify possible associations between factors assessed at baseline and withdrawal due to MTX-related AEs or liver toxicity at follow-up.
Although significantly more patients in the intensive strategy group experienced MTX-related AEs than in the conventional strategy group, all recorded AEs were relatively mild. A higher body mass index (BMI) was significantly associated with withdrawal due to MTX-related AEs in the multiple regression analyses (odds ratio=1.207, 95% confidence interval 1.02 to 1.44, p=0.033). There was a trend towards an association between diminished creatinine clearance and MTX withdrawal. For liver toxicity, increased serum liver enzymes at baseline were associated with liver toxicity during follow-up.
Although the occurrence of AEs in the intensive strategy group was higher than in the conventional strategy group, the previously observed clinical efficacy of an intensive treatment strategy seems to outweigh the observed toxicity profiles. When starting MTX, attention should be given to patients with a high BMI and those with increased levels of liver enzymes and decreased renal function.