Objectives: To identify (a)whether TNFi-drug levels/anti-drug antibodies (ADAbs) are associated with treatment response and disability in psoriatic arthritis (PsA) patients (b)factors associated with TNFi-drug levels.
Methods: Patients were recruited from a national multi-centre prospective cohort with longitudinal serum samples and disease-activity scores/Health assessment Questionnaire(HAQ) measurement over 12-months.
Results: Adalimumab-drug levels were significantly associated with ΔDAS28 [β=0.055 (95%CI: 0.011, 0.099) p=0.014] and inversely with HAQ over 12-months [β=-0.022 (95%CI: -0.043, -0.00063]. Factors significantly associated with adalimumab drug levels were ADAb levels and body mass index.
Conclusions: Drug-level testing in adalimumab-initiated PsA patients may be useful in determining treatment response/disability over 12-months.