POISE

Introduction

Psoriatic arthritis (PsA) is a type of arthritis that develops in around 15% of people with the skin condition psoriasis, causing swollen and painful joints.  It affects around 150,000 people in the UK but there is little research on the best way to treat them.  We currently use a ‘step-up’ approach for all patients, whether they have mild or severe disease. This means at first one standard arthritis drug is used, then two standard drugs together and finally newer stronger biologic drugs for patients not responding to the other drugs. It is possible that patients with mild disease may not need any of these treatments, suffering unnecessary side effects such as sickness, stomach upsets, infections and liver problems.

Aims

To see if it would be possible to run a trial looking at whether patients with mild disease can be treated successfully without being put onto more powerful arthritis drugs.

Design and Methods

This trial was embedded within an existing cohort study monitoring patients with a new diagnosis of PsA.   Patients are regularly monitored with treatment increased using the ‘step-up’ approach described above until the target is achieved.  The POISE study used a Trials Within Cohorts (TWiCs) design.

Patients with newly diagnosed mild psoriatic arthritis were included in the study.  To be classified as mild, patients had to have <5 joint that were inflamed, low disease activity score and an absence of poor prognostic factors (CRP<5mg/dL, HAQ <1, no radiographic erosions). Participants were randomised open-label to either standard care with ‘step up’ DMARD therapy or to symptomatic therapy with non-steroidal anti-inflammatory drugs (NSAIDs) and local corticosteroid injections to inflamed joints.  As this was a feasibility study, to see if a big study could be successful, the key outcomes to be studied were the proportion of eligible cohort patients, consent and study completion rate.

Results

Over the 15-month study period, only 1 eligible patient was randomised. Although oligoarthritis (<5 active joints) patients represented 45% of patients in this early PsA cohort, the majority did not have mild disease (24% raised CRP, 51% moderate disease activity, 13% radiographic damage and/or poor function).  Of those meeting trial inclusion criteria, many patients refused treatment in the observational cohort prior to an invitation into the trial as they did not wish to be treated with DMARDs.

Conclusion

The study was not feasible as designed. Oligoarthritis represents around half of initial PsA presentations, but the majority starting therapy have high impact disease.  A small proportion have mild oligoarticular disease but many are not keen on treatment with DMARDs, given the potential side effects of these medications.  Further research is needed to support evidence-based treatment in this subgroup.

Trial registration number - ClinicalTrials.gov (NCT03797872) and EudraCT (2018-001085-42).

Funding

This study was funded by the National Institute of Health Research (CS-2016-16-016) and supported by the NIHR Oxford Biomedical Research Centre.