ObjectiveTo identify a core set of domains (outcomes) to be measured in psoriatic arthritis (PsA) clinical trials that represent both patients' and physicians' priorities.MethodsWe conducted (1) a systematic literature review (SLR) of domains assessed in PsA; (2) international focus groups to identify domains important to people with PsA; (3) two international surveys with patients and physicians to prioritise domains; (4) an international face-to-face meeting with patients and physicians using the nominal group technique method to agree on the most important domains; and (5) presentation and votes at the Outcome Measures in Rheumatology (OMERACT) conference in May 2016. All phases were performed in collaboration with patient research partners.ResultsWe identified 39 unique domains through the SLR (24 domains) and international focus groups (34 domains). 50 patients and 75 physicians rated domain importance. During the March 2016 consensus meeting, 12 patients and 12 physicians agreed on 10 candidate domains. Then, 49 patients and 71 physicians rated these domains' importance. Five were important to >70% of both groups: musculoskeletal disease activity, skin disease activity, structural damage, pain and physical function. Fatigue and participation were important to >70% of patients. Patient global and systemic inflammation were important to >70% of physicians. The updated PsA core domain set endorsed by 90% of OMERACT 2016 participants includes musculoskeletal disease activity, skin disease activity, pain, patient global, physical function, health-related quality of life, fatigue and systemic inflammation.ConclusionsThe updated PsA core domain set incorporates patients' and physicians' priorities and evolving PsA research. Next steps include identifying outcome measures that adequately assess these domains.

Objectives The current psoriatic arthritis (PsA) Core Domain Set defines core domains to be measured in randomized controlled trials (RCTs) and longitudinal observational studies (LOS) and was published in 2006. At the Outcome Measures in Rheumatology (OMERACT) meeting in 2014, researchers, clinicians and patients unanimously voted for updating the PsA Core Domain Set to include the patient perspective in accordance with OMERACT Filter 2.0. Herein we report the proceedings of the PsA Workshop at the OMERACT meeting in 2016 including studies presented in the plenary, results of breakout group discussions, and final voting and endorsement of the 2016 updated PsA Core Domain Set. Methods We conducted research to develop the updated PsA Core Domain Set. At OMERACT 2016 this work was presented, discussed in breakout groups and the updated PsA core domain set was voted on and endorsed by OMERACT participants. Results The updated PsA Core Domain Set includes: musculoskeletal disease activity, skin disease activity, fatigue, pain, patient global, physical function, health related quality of life and systemic inflammation which are recommended for all RCTs and LOS). Economic cost, emotional well-being, participation and structural damage are important but not required in all RCTs and LOS. Independence, sleep, stiffness and treatment burden on the research agenda. Conclusion The updated PsA Core Domain Set was endorsed at OMERACT 2016. Next steps for the PsA working group include evaluation of available outcome measures for each of the core domains and development of a PsA core outcome measurement set.

The Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA)- Outcome Measures in Rheumatology (OMERACT) PsA Core Set working group recently published the updated 2016 psoriatic arthritis (PsA) core domain set, a set of disease features that should be measured in all clinical trials. At the GRAPPA annual meeting in July 2016, the PsA working group presented the updated PsA core domain set endorsed by 90% of participants at OMERACT in May 2016 and held a working group meeting where the working group drafted a roadmap for the development of the PsA core outcome measurement set. In this manuscript, we review the development process of the PsA core domain set and the ongoing and proposed workstreams for development of a PsA core measurement set.

BackgroundThe aim was to study changes in immunohistochemical expression markers of synovial and skin inflammation, clinical outcomes and magnetic resonance imaging (MRI) scores with abatacept treatment in patients with psoriatic arthritis (PsA).MethodsBiological-treatment-naïve PsA patients with active disease including synovitis of a knee were enrolled in this single-centre, crossover study. Patients were randomised to receive intravenous abatacept 3 mg/kg of body weight or placebo infusion on day 1, 15 and 29; thereafter abatacept 10 mg/kg of body weight was administered every 28 days for 5 months. Clinical data were collected at each visit. Synovial biopsy of the involved knee was obtained at baseline and 2 and 6 months. MRI of the same knee and skin biopsy was performed prior to arthroscopy.ResultsFifteen patients were recruited. Significant improvements in the joint-related measures were observed; 90% were European League Against Rheumatism criteria responders and 30% achieved psoriasis area severity index (PASI)50 at 6 months. Reduction in synovitis (P = 0.016) and vascularity (P = 0.039) macroscopic scores consistent with decrease in total MRI score (P = 0.016) were noticed. Abatacept decreased the immunohistological expression of FOXP3+ cells (P = 0.027), specifically the expression of CD4+FOXP3+ regulatory T cells (Tregs) (P = 0.008) in the synovium over 6 months. There was no significant clinical or immunohistological change in any of the skin measures.ConclusionThis is the first study assessing synovial and psoriatic skin immunpathological changes following abatacept treatment in PsA. Reduction in Treg expression in the synovium but not in the psoriatic lesion suggests abnormal Treg function in PsA with differential suppressive capacity in the synovium compared to the lesional skin. The results of this study demonstrate that abatacept 10 mg/kg of body weight might be an effective treatment option for joint disease in patients with PsA.Trial registrationIrish Health Products Regulatory Authority. Trial registration number: CT 900/489/1 – Abatacept (case number: 2077284, EudraCT Number: 2009-017525-19, Protocol number: 77777). Registered on 12 March 2010.