Defining Cut-off Values for Widely-used Composite Scores and Patient-reported Outcome Measures in Psoriatic Arthritis Corresponding to Remission and Flare Assessed by the Physician and the Patient

Introduction: Psoriatic arthritis (PsA) is a heterogeneous chronic disease with a significant patient-perceived impact leading to pain, fatigue, impaired function and quality of life and psychological distress. Remission is the announced treatment target in PsA. Several definitions of remission have been proposed including definitions on composite scores such as the Disease Activity in Psoriatic Arthritis (DAPSA) and Minimal Disease Activity (MDA), however their translation into the patient's perspective is lacking. Flares are frequent in PsA and are important for patients but are not well-defined from the physician's perspective. Although some work is ongoing regarding remission and flare from the patient's perspective, currently no information allows to cross-tabulate and compare the patient and physician perspectives regarding remission and flare in PsA .

The objective is to define cutoffs of the most widely used composite scores and PROs, for levels corresponding to remission/low disease activity and for changes in levels corresponding to flares, in PsA, when remission/low disease activity and flare are defined from the patient and physician perspective.

Methods Design: the ReFlaP (Remission/Flare in PsA) study is a prospective, multicentric international, longitudinal, observational study. It will take place in 2017-18 in 25 centers across Europe, North and South America and Asia. Investigators plan to include a total of 450 patients. The inclusion period will last 6 months; each center will include around 20 patients. Each patient is seen twice at baseline and at 1-6 months (follow-up visit) in the context of usual care.

Patients: Consecutive adult patients with definite PsA (according to ClASsification of Psoriatic ARthritis (CASPAR) criteria and confirmation by a rheumatologist), more than 2 years of disease duration, and will be included after signed informed consent.

Data collection: During each visit, physicians will collect data on the disease and on disease activity: 66 swollen joint counts, 68 tender joint counts, tender entheseal points (Leeds Enthesitis Index) and body surface area of psoriasis. This will allow calculation of most of the usual composite scores of PsA: Arythmetic Mean of Desirability Functions modified (AMDF modified), Disease Activity in PSoriatic Arthritis (DAPSA), clinical DAPSA (c-DAPSA), Minimal Disease Activity (MDA) and Psoriatic Arthritis Disease Activity Score (PASDAS). Well-validated Patient Reported Outcomes will be collected from patients: Patient Global Assessment (PGA), Pain, Health Assessment Quality (HAQ), PSoriatic Arthritis Impact of Disease (PSAID), Psoriatic Arthritis Quality of Life (PsAQoL), 12-Item Short Form Health Survey (SF-12), Patient Acceptable Symptom State (PASS) and Minimal clinically important differences (MCID) as well as the recent Flare questionnaire proposed by GRAPPA. Assessment of disease activity status (i.e. remission or flare) will be performed by both physician and patient using global questions.