Psoriatic Arthritis - PROMPT

Patient and public involvement Our programme directly stems from key areas identified as major priorities for research by NICE guidelines on assessment and management of psoriasis, focus groups of people with PsA, and our own patient research partners. Patient research partners will have an active role in all aspects of the programme. Background and Rationale Psoriatic arthritis (PsA) affects approximately 1 in 3 people with pre-existing psoriasis. However, screening patients with psoriasis for PsA in primary care/dermatology clinics has revealed a high prevalence (14-29%) of undiagnosed disease. Preliminary studies, including our own, have identified a significant need for the earlier diagnosis of PsA. There is indirect evidence that delay in diagnosis results in unfavourable outcome with increased health costs and work disability. There is solid evidence that early treatment lessens long-term disease burden in rheumatoid arthritis but this has not yet been shown for PsA. As psoriasis precedes PsA in ~70% of cases, this provides a unique opportunity to develop an optimal screening strategy to apply to people with psoriasis and determine whether early diagnosis of PsA is clinically and cost effective. From studies we have led on we know that outcome measures for PsA need to be refined to encompass domains that people with PsA have identified as important, particularly fatigue pain, skin disease and work disability. Aims and objectives We aim to provide an evidence-based framework for recommendations on an effective and acceptable screening strategy for the early identification of PsA in people with psoriasis in primary care and their subsequent management by: Theme One: Screening and Early Diagnosis investigating the clinical effectiveness (1A) and cost-effectiveness (1C) of detecting undiagnosed PsA determining an effective screening strategy for early detection of PsA by using patient questionnaires (1B) investigating the role of modifiable risk factors in the development of PsA in people with psoriasis ( 1D) identifying current barriers to diagnosis of PsA (1E) Theme Two: Outcome Measurement in Early Disease ensuring outcome measures encompass aspects of early disease that are important to people with psoriatic arthritis (2A, 2B) Research Plan Theme one: Screening and Early diagnosis Study 1A. We will undertake a two-arm parallel-group cluster randomised controlled trial of enhanced surveillance for PsA versus standard care to determine whether identifying undiagnosed PsA in primary care leads to improved outcomes. The primary outcome will be physical function measured by the Health Assessment Questionnaire (HAQ) at two years. Secondary outcomes will include quality of life assessments, health resource utilisation and work productivity. A total of 138 patients with PsA (69 per arm) are required to be diagnosed to have 80% power for detecting a difference in HAQ scores of 0.35 units at 5% significance level. After adjustment for the cluster design and anticipated 20% withdrawal we require a sample size of 2000 patients across 80 general practices (40 practices per arm). Study 1B. Participants from practices randomised to the enhanced surveillance arm of 1A will be included in a diagnostic accuracy study of the CONTEST and PEST screening questionnaires. A diagnosis of PsA will be made according to the CASPAR criteria by a rheumatologist who is blinded to the questionnaire responses. With 1000 participants the precision of sensitivity is estimated at ±11.5% and specificity ±4.8% taking into account practice clustering. Study 1C. A decision analytic model will be developed to estimate the clinical outcomes and cost-effectiveness of the detection of undiagnosed PsA using data from 1A and to compare the cost-effectiveness of PEST and CONTEST. Study 1D. We will use the Clinical Practice Research Datalink to describe the evolut