Responders Responders with shortened period of efficacy Non-responders with production of antibodies Non-responders without production of antibodies
IFX ≥ 1 0 – 0.5 0 ≥ 1
ATI negative negative positive negative
Clinical efficacy good response shortened period of efficacy shortened period of efficacy, later no response no response
Recommendation continue in the treatment without changes reduce maintenance interval to 6 weeks add MTX reduce maintenance interval to 6 weeks change biological ETA > ADA or UST change biological - UST
Table 3: Proposed therapeutic management based on clinical efficacy, trough levels of IFX and ATI. ADA–adalimumab, ETA–etanercept, UST–ustekinumab, MTX– methotrexate.