Imaging Treat-to-target Strategy vs Conventional Treat-to-target Strategy in Psoriatic Arthritis

The main objective is to assess if a treat-to-target strategy implementing structured imaging assessments leads to better patient outcome in terms of sustained remission compared to a conventional treat-to-target strategy in psoriatic arthritis. Main inclusion criteria are: \>18 years of age, Clinical diagnosis of psoriatic arthritis (PsA), Fulfillment of ClASsification of Psoriatic Arthritis (CASPAR) criteria, Indication for treatment with disease modifying anti-rheumatic drugs according to treating physician Primary endpoint: Sustained remission, defined as Very Low Disease Activity (VLDA) at 16, 20 and 24 months Secondary endpoints: Individual and composite disease activity measures and remission criteria, inflammation assessed by ultrasound, health related quality of life and adverse events. Study design: A two-arm, parallel-group, single-blind, treatment strategy study where patients are randomized 1:1 to a conventional treat-to-target follow-up strategy with structured clinical assessment of disease activity or an imaging informed treat-to-target follow-up strategy with both structured clinical assessment of disease activity and structured imaging assessment of disease activity. Duration of follow-up is 24 months. All patients are treated according to an algorithm based on current European recommendations. The conventional treatment target, applicable to both arms and the sole target in the conventional arm, is all of: Disease Activity index in Psoriatic Arthritis (DAPSA) remission (≤3), Enthesitis ≤1, Psoriasis Body Surface Area ≤3% Intervention: A treat-to-target treatment strategy incorporating information from ultrasound assessment of joints, tendons and entheses (at every visit), and magnetic resonance imaging (MRI) of spine and sacroiliac (SI)-joints at baseline and 1 year, in addition to clinical information. Specifically, this means that these additional measures will be added to conventional treat to target: * If evidence of enthesitis or axial inflammation on imaging the patient will progress directly to biological disease modifying antirheumatic drug in the treatment algorithm * If evidence of ongoing inflammation (power Doppler\>0) on ultrasound assessment of joints, tendons or enthesis, the patient will be classified as not having reached their treatment target