OA31 Investigating treatment response heterogeneity in psoriatic arthritis patients from the OUTPASS study

Abstract Background/Aims To investigate the heterogeneity of treatment response in patients with psoriatic arthritis (PsA) who are commencing a biologic (b) or targeted synthetic (ts) DMARD and identify associations between different responses and clinical features at drug initiation. Methods Patients from the UK prospective observational cohort study, Outcomes of Treatment in Psoriatic Arthritis Study Syndicate (OUTPASS) had demographic and clinical data collected at 0, 3, 6, and 12 month follow-up time points after initiating b/tsDMARD therapy. Clusters of patients were identified based on their DAS28 composite and PsARC subcomponent scores over time via Group Based Trajectory Modelling. Only patients with at least 1 data point recorded in each component over the 12-month follow-up were included. Associations between identified clusters, demographic and clinical factors at treatment initiation were characterised through univariable and multivariable logistic regressions. Univariable models were corrected for multiple testing with 5% false discovery rate threshold correction. Missing risk factor data were imputed for regression analyses. Results Of the 569 patients, two clusters were uncovered following b/tsDMARD therapy: responders (55%) and non-responders (45%). The non-responder group was characterised by higher DAS28 and PsARC component scores across all time points and worsening of the patient global assessment component of the PsARC score after 3 months. Univariable models identified asthma, older age, higher baseline DAPSA, and initiating ustekinumab as significantly associated with non-response after multiple testing correction (Table 1). While depression, angina, myocardial infarction, and female gender were significantly associated with non-response using univariable analysis, the association was not maintained following correction for multiple testing. Multivariable logistic regression identified asthma, higher baseline DAPSA , lower baseline CRP, and ustekinumab therapy as significantly associated with non-response. Conclusion Our data identified two patterns of response in PsA patients commencing an advanced therapeutic. Associations found in previous PsA cohorts such as lower CRP and higher DAPSA correlating with non-response were replicated in this study, but presence of depression, older age, and female gender were not. Asthma has not previously been reported to be associated with non-response in PsA cohorts and may be confounded by presence of concurrent psoriasis or IL-17 dysregulation. Disclosure D. Chong: None. M. Khasru: None. S. Shoop-Worrall: None. A. Barton: None. H. Chinoy: None. M. Jani: None. J. Bluett: Grants/research support; JB has received a research grant award from Pfizer and travel/conference fees in the last 3 years from Fresenius Kabi and Novartis.