TNF and rheumatoid arthritis: In light of the aforementioned, the purpose of the present study was to conduct a systematic review of cost-effectiveness studies of abatacept in order to evaluate the role of this agent in the treatment of moderate to severe rheumatoid arthritis, specializing to treatment algorithms after previous inadequate response or intolerance to disease modifying antirheumatic drugs (DMARDs) and/or TNF inhibitors.