The aim of this study was to evaluate the cost utility of certolizumab pegol compared with other standard first-line TNF-inhibitor therapies licensed and marketed in Spain in 2009 (etanercept, adalimumab, infliximab), administered with or without methotrexate for the treatment of patients with moderate-to-severe RA who have had an inadequate response to methotrexate alone. Here, TNF is linked to rheumatoid arthritis.