In our study, in terms of QALYs gained, certolizumab pegol was the most effective therapy in combination with methotrexate at the €30,000/QALY willingness-to-pay (WTP) threshold compared with other TNF inhibitors recommended in Spain in 2009 (adalimumab, etanercept and infliximab) for the treatment of patients with active RA who did not respond adequately to DMARDs. Here, TNF is linked to rheumatoid arthritis.