Finally, a cost-effectiveness study on the efficiency of early treatment with biologicals [65] found that for RA patients refractory to csDMARD, adding a biosimilar TNF-alpha inhibitor to MTX at 6 months increased the total treatment cost by only £70, compared to continuing MTX monotherapy and waiting until 12 months (price in pounds sterling for 2017) [65]. This evidence concerns the gene TNF and rheumatoid arthritis.