Measurement properties of instruments assessing peripheral arthritis disease activity in spondyloarthritis: a systematic literature review

Objectives: The Assessment of SpondyloArthritis International Society-Spondyloarthritis and Peripheral Arthritis Disease Activity Instrument Selection and Evaluation (ASAS-SPARADISE) project aims to identify instruments to assess disease activity due to peripheral arthritis in axial (axSpA) and peripheral spondyloarthritis (pSpA). We aimed to summarise and compare the measurement properties of instruments used for this purpose as part of the ASAS-SPARADISE.

Methods: A systematic literature review (Medline/EMBASE/Cochrane; until February 2025) was conducted following the Population-Instrument-Measurement framework. Eligible studies included adults with axSpA or pSpA and peripheral arthritis. Instruments retained from a previous review, after domain-match and feasibility assessment, included: Patient Global Assessment (PGA), swollen joint count (66/44), tender joint count (68/44), C reactive protein (CRP), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Axial Spondyloarthritis Disease Activity Score (ASDAS), Disease Activity Index for Psoriatic Arthritis (DAPSA) and Disease Activity Score using 44 joints. Measurement properties evaluated were construct validity (correlation hypotheses; known-groups discrimination) and discrimination (test-retest reliability, responsiveness; clinical trial discrimination; thresholds of meaning). Risk of bias was assessed using the Outcome Measures on Rheumatology (OMERACT) Good Methods Checklist and evidence was synthesised following OMERACT rules (GREEN—good; AMBER—adequate; RED—poor performance).

Results: Of 4,364 records screened, eight studies were eligible. Evidence in axSpA was limited to PGA, CRP and BASDAI, rating mostly AMBER for construct validity, longitudinal construct validity and discrimination in clinical trials. In pSpA, composite instruments showed better results, with BASDAI, ASDAS and DAPSA rating mostly GREEN. No study provided test-retest reliability or thresholds of meaning.

Conclusions: Evidence supporting instruments to assess peripheral arthritis in spondyloarthritis remains scarce, especially in axSpA. Composite instruments in pSpA performed better, but evidence gaps persist, highlighting the need for validated, domain-specific instruments.

PROSPERO registration number: CRD420251177596.