Selection of relevant domains and instruments for the ASAS core set to assess axial spondyloarthritis in clinical practice: a Delphi survey of stakeholders

Objectives The Assessment of SpondyloArthritis international Society (ASAS) aims to develop a core set for the assessment of axial spondyloarthritis (axSpA) in clinical practice to improve standardisation. The first step is to explore stakeholder preferences regarding candidate domains and instruments used for their assessment. Methods A scoping literature review was conducted to inform the development of a Delphi survey comprising 3 planned rounds, with provision for additional rounds. Three stakeholder groups (ASAS members, non-ASAS rheumatologists, and patients with axSpA) participated. The first and second rounds aimed to select domains for the core set, the third round aimed to select instruments, and an additional (fourth) round re-evaluated the inclusion of 1 domain. The selection of domains and instruments considered 2 assessment scenarios: ‘routine' and ‘extended' outpatient visits. Results The literature review identified heterogeneous candidate domains. Overall, 156 of 201 (78%) ASAS members, 173 non-ASAS rheumatologists, and 167 patients participated in the first Delphi round. Following 4 rounds, 5 domains were selected for routine visits (‘disease activity', ‘pain', ‘peripheral manifestations', ‘extra-musculoskeletal manifestations', and ‘treatment aspects') and 4 supplementary domains for extended visits (‘structural damage', ‘overall functioning and health', ‘comorbidities', and ‘mobility'). One recommended instrument was selected for each routine visit domain, alongside several optional instruments. At least 1 recommended or optional instrument was selected for each extended visit domain. Conclusions Five domains for routine visits and 4 supplementary domains for extended visits, with corresponding instruments, were selected based on stakeholder preferences to be considered for the ASAS core set to assess axSpA in clinical practice.