ASAS Recommendations on Reporting Axial Spondyloarthritis Clinical Trials


The Assessment of SpondyloArthritis international Society–Outcomes Measures in Rheumatology (ASAS-OMERACT) Core Outcome Set for ankylosing spondylitis (AS) was developed almost three decades ago and, reflecting the progress made in the field, this original COS was updated into a COS for the entire axial spondyloarthritis (axSpA) spectrum. For the new ASAS COS, first the domain set was updated which tells what to measure and thereafter the instrument set was updated which informs how to measure (1, 2). The current domain set includes seven mandatory domains for all studies and three additional mandatory domains for studies evaluating disease-modifying antirheumatic drugs (DMARDs). In the instrument set, seven mandatory instruments were selected for all trials, nine additional mandatory instruments for DMARD trials. Furthermore, eleven extra instruments were also endorsed and can be used in addition to those included in the COS (2).

While the update ASAS COS provides axSpA trialists guidance on which instruments to use in axSpA clinical trials, recommendations on how to report the outcomes of axSpA clinical trials and which baseline features should be reported to adequately describe the study population and interpret results are not available.


The aim of this ASAS project is to create expert recommendations for axSpA clinical trials on which baseline features to collect and how to report them, which instrument outcomes to present, and how to present the COS data in text, tables and graphs.


After project approval in September 2023, the steering group established a working group consisting of seven additional ASAS members all senior SpA clinicians and researchers. The working group was complemented by two Young ASAS members.

Recommendations on which and how to report axSpA trials baseline features and outcomes were developed in three steps: i) using key axSpA clinical trials the project steering group identified those baseline features and outcomes (related to the instruments in the ASAS COS) that should be presented and how to do this; ii) The steering group proposal was presented, discussed and modified in a working group meetings iii) The workgroup proposal were  discussed and voted on by ASAS full members during the 2024 annual ASAS workshop and at the time of this writing a manuscript is being drafted.

Timelines: 2023-2024

Steering committee

Floris A. van Gaalen, Victoria Navarro-Compán, Désirée van der Heijde

Working group

Xenofon Baraliakos, Filip van den Bosch, Ihsane Hmamouchi (Y-ASAS), , Robert Landewé, Pedro Machado, Helena Marzo-Ortega, Denis Poddubnyy, Sofia Ramiro, Valeria Rios Rodriguez (Y-ASAS)


  1. Navarro-Compán V, Boel A, Boonen A, Mease P, Landewé R, Kiltz U, et al. The ASAS-OMERACT core domain set for axial spondyloarthritis. Semin Arthritis Rheum. 2021;51(6):1342-9.
  2. Navarro-Compán V, Boel A, Boonen A, Mease PJ, Dougados M, Kiltz U, et al. Instrument selection for the ASAS core outcome set for axial spondyloarthritis. Ann Rheum Dis. 2022.