Objective: to assess cost-effectiveness of three different initial treatments in seronegative DMARD-naïve RA patients, defined as patients from the tREACH trial with an intermediate probability of developing persistent arthritis who fulfilled RA 2010 criteria and were RF and ACPA negative at baselineStudy design: cost–utility study in the context of clinical trial of 1 year duration.Study setting: patients recruited from eight rheumatology centres. This evidence concerns the gene PRTN3 and rheumatoid arthritis.