O13 Which composite measure best reflects disease activity and predicts treatment change in psoriatic arthritis?

Abstract

Abstract Background/Aims Multiple composite measures of disease activity are available and used in psoriatic arthritis (PsA) research; however, poor agreement remains amongst clinicians on the optimal measure of disease activity. Research to date has focused on polyarticular PsA, despite oligoarticular disease accounting for around half of cases in clinical practice. We aim to compare the ability of Composite Psoriatic Disease Activity Index (CPDAI), Psoriatic ArthritiS Disease Activity Score (PASDAS), Disease Activity score for PSoriatic Arthritis (DAPSA), GRAppa Composite scorE (GRACE) and Disease Activity Score 28 CRP (DAS28-CRP) to assess disease activity and predict treatment change, amongst usual care patients with oligoarticular and polyarticular psoriatic disease. Methods The Group for Research and Assessment of Psoriasis and Psoriatic Arthritis Composite Exercise (GRACE) dataset was utilised. Oligoarthritis was defined as < 5 active joints. Reference measures were clinician and patient opinions on disease control and whether treatment was escalated. Patients with baseline data for all composite measures were included. The ability of each composite measure to predict treatment change and capture disease activity was compared using the Mann-Whitney U test. Results Data were available for 271 patients (152 oligoarthritis, 119 polyarthritis). The mean age, duration of PsA and psoriasis were similar for both groups. A higher proportion of oligoarticular patients were male. Patients with polyarticular disease had higher disease activity in skin, enthesitis and dactylitis. Using both patient and physician definitions of disease control, all composite measures were able to differentiate between patients with active and quiescent disease, regardless of disease subtype (p < 0.05). PASDAS demonstrated the largest differentiation in score. Differences between active and inactive disease scores were more pronounced in oligoarticular disease. PASDAS demonstrated the greatest ability to predict treatment change in both oligoarticular and polyarticular disease. Interestingly, DAPSA could not predict treatment change in polyarticular patients, p = 0.074 (Table 1). Conclusion This is the first study to compare composite measures, in oligoarticular and polyarticular PsA in a multinational cohort. All composite measures of disease activity were able to differentiate between active and inactive disease in both subtypes. PASDAS demonstrated the largest discrimination in both polyarticular and oligoarticular disease, suggesting greatest clinical and research utility. Disclosure L. Tucker: None. P. Helliwell: None. L. Coates: None.