P014 Treatment response in psoriatic arthritis: a comparison between the disease activity scores psoriatic arthritis response criteria and disease activity score-28

Abstract Background/Aims Despite NICE guidelines recommending the use of the PsA response criteria (PsARC), to assess response to biologic therapies in patients with psoriatic arthritis (PsA), some clinicians use the Disease Activity Score (DAS-28) criteria, developed for rheumatoid arthritis. However, whether the two scores are interchangeable and/or capture similar information has not yet been explored. Here, we investigate the differences and overlap between these two disease activity scores, in identifying good/poor responders, in PsA. Methods Utilising treatment response data from the OUTPASS cohort; a UK based multi-centre observational study, PsA patients assessed with PsARC and DAS-28 scores were calculated at baseline (pre-treatment), 3-months and 6-months (3M),(6M), following treatment, where available. EULAR good/moderate response was combined and compared with PsARC responder status. Subgroup analysis of patients with both PsARC and DAS-28 scores at either 3M or 6M, were tested for agreement using the Cohen’s Kappa test. Statistical tests were also used, as appropriate, to investigate differences between the baseline subcomponents, in the observed concordant and discordant data. Results Response data from 418 patients was available. An average of 76% were classified as responders according to PsARC, and 80% according to the EULAR response criteria, for both 3M and 6M, with 12% discordance. A subgroup analysis of 218 patients assessed with both scores, (up to 6M), revealed 17.9% responder discordance between PSARC and DAS-28, and 82.1% concordance. The Cohen’s Kappa test defined the assessment of responder/non-responder outcome, as an ‘almost perfect agreement’ (0.82) between the two criteria. Further statistical analyses, of baseline subcomponents, of both response criteria, between these discordant/concordant subsets, showed no significant difference, except for PsARC Physician’s and Patient’s Global Assessments (PhGA), (PGA), (P = 0.01, P = 0.02, Table 1). Conclusion PsARC and EULAR response criteria show ‘almost perfect agreement’, strongly supporting clinical use for either score. PhGA, (not a subcomponent of DAS-28) and PsARC PGA were the only significantly different (P < 0.05) components between the discordant and concordant groups, highlighting the importance of considering psychosocial factors which may affect pain tolerance and treatment response. Comparative analyses with other widely used scores, such as DAPSA, would also be informative for future work. Disclosure K. Patel: Grants/research support; This project has received support from the Innovative Medicines Initiative 2 Joint Undertaking (JU) under grant agreement No 101007757 (HIPPOCRATES), the JU receives support from the European Union’s Horizon 2020 research and innovation programme and EFPIA, the results reflect only the author's view and the JU are not responsible for any use that may be made of the information it contains.. N. Nair: None. M. Jani: None. H. Chinoy: Consultancies; H.C. has received Consulting for PTC Therapeutics. Member of speakers’ bureau; H.C. has received fees as a speaker for GSK, UCB. Other; H.C. for Advisory Board member for Astra Zeneca, Pfizer, Argenx, Galapagos; Data and Science Monitoring Board chair for Horizon Therapeutics. J. Bluett: Grants/research support; J.B. has received a research grant award from Pfizer and travel/conference fees from UCB, Fresenius Kabi, Pfizer and Eli Lilly. (Pfizer: WI239449). A. Barton: Grants/research support; A.B. has received research grants from Bristol Myers Squibb and Pfizer and speaker fees from Galapagos.. P. Curry: None.