Multicentre ObservatioNal Initiative in Treat to Target Outcomes in Psoriatic Arthritis

Psoriatic Arthritis (PsA) is an inflammatory arthritis estimated to occur in 15% of people with psoriasis, affecting around 150,000 people in the United Kingdom (UK). The 2015 European League Against Rheumatism (EULAR) Treatment recommendations for PsA incorporating as its first recommendation that "treatment should be aimed at reaching the target of remission or, alternatively, minimal/low disease activity, by regular monitoring and appropriate adjustment of therapy". Despite the evidence and the EULAR recommendations supporting 'treat to target' in PsA, it has not been widely implemented due to concerns about feasibility and cost-effectiveness. This cohort will establish a pragmatic feasible 'treat to target' approach in a real-life clinic population which we believe can provide similar clinical and health-related quality of life outcomes.

The primary outcome will be the proportion of patients achieving a good response measured by the PsA Disease Activity Score (PASDAS) at 48 weeks. Additional domains including participation, fatigue and emotional wellbeing will be assessed for the first time. Finally the costs of this pragmatic intervention will be established using health economic analysis.All patients will receive treatment as usual following the current British Society of Rheumatology (BSR) and EULAR guidance as standard of care.

As a cohort for a "Trials within Cohorts" or TWiCs design, the patients consenting to participate will also be asked if they consent to be approached for future interventional trials linked to the cohort and whether they consent for their data to be used as a comparator in these future interventional studies.

Inclusion criteria

• Participant is willing and able to give informed consent for participation in the study.
• Male or Female
• Aged 18 years or above.
• Clinical diagnosis of PsA based upon the Classification of PsA (CASPAR) criteria(23))
• Active PsA defined by ≥1 tender or ≥1 swollen joint or ≥1 enthesis (site of attachment of tendon to bone)
• Not previously received treatment with synthetic or biologic disease-modifying anti-rheumatic drugs (DMARDs) for their articular disease.
• In the Investigator's opinion, is able and willing to comply with all study requirements.

Exclusion criteria

• Current or previous treatment of arthritis with synthetic DMARDs (including methotrexate, leflunomide or sulfasalazine) or biologic DMARDs (including tumour necrosis factor (TNF), interleukin (IL)12/23 or IL17 inhibitor therapies) or targeted synthetic DMARDs (phosphodiesterase (PDE) 4 or Janus kinase (JAK) inhibitor therapies).
• Use of investigational therapies within 1 month or 5 biological half-lives of the baseline study visit(whichever is longer)
• Women who are pregnant, nursing or planning pregnancy during the following 12 months.