Background/Purpose: Peripheral manifestations (peripheral arthritis, enthesitis, dactylitis) of axial spondyloarthritis (axSpA) and peripheral spondyloarthritis (pSpA) represent a significant burden for patients, but are understudied. Our aim was to evaluate the frequency of 1) assessment and reporting of peripheral manifestations in clinical trials of axSpA and pSpA (psoriatic arthritis excluded) 2) use of specific instruments for each peripheral manifestation.

Methods: A systematic literature review (SLR) was carried out, starting from available SLRs conducted for the 2016/2022 updates of the ASAS-EULAR axSpA management recommendations (≤2021).1-3 The search was updated to March 2024 (PROSPERO CRD42024532666). The research question followed the PICOT framework: Population: adult patients with axSpA or pSpA;

Intervention: biological and targeted synthetic DMARDs; Comparator: active comparator, placebo; Outcomes: Frequency of assessment of each peripheral manifestation, and of use of various specific instruments (e.g swollen joint count [SJC] for arthritis); Type of studies: randomised controlled trials (RCTs), controlled clinical trials. Study protocols, if available, or trial descriptions from ClinicalTrials.gov were checked for information on peripheral manifestations assessment. Risk of bias (RoB) was assessed by the Cochrane tool. For synthesis, descriptive statistics were used.

Results: In total, 100 trials were included for axSpA and 4 for pSpA (55 and 2 at low RoB, respectively). In axSpA, n=54 trials assessed peripheral arthritis, n=64 enthesitis and n=10 dactylitis. Not all of the studies actually reported these results, and only few addressed the subpopulation with the peripheral manifestation at baseline (Fig 1). The most frequently used instruments for peripheral arthritis (out of n=54) were SJC based on 44 (50%), 66 (11%) and 64 (9%) joints, and tender joint counts (TJC) based on 44 (24%), 46 (15%) and 68 (11%) joints. No studies assessed composite scores involving joint counts (e.g. DAS). For enthesitis (n=64 trials), the majority of studies used the MASES (87%), followed by the SPARCC enthesitis index (11%), question 4 of the BASDAI (8%) and the LEI (3%). The main instrument used for dactylitis was digit count (4/10, 10%); in 3/10 trials dactylitis was collected as adverse event. There was a tendency towards a higher frequency of reporting, and reporting in subpopulations with peripheral manifestations, in RCTs at lower RoB (Fig 2). In pSpA, all 4 trials assessed (and reported on) peripheral arthritis; 2 also assessed enthesitis and dactylitis.

Conclusion: In axSpA, peripheral manifestations were assessed as outcome in less than 2/3 of trials. The most frequently used instruments were SJC and TJC for peripheral arthritis, MASES for enthesitis and digit count for dactylitis. Outcomes were typically not reported in the subpopulation with known peripheral arthritis/enthesitis/dactylitis at baseline.

Fig 1. Frequency of assesment and reporting, including reporting in subpopulations, of each peripheral manifestations

Fig 2. Frequency of assesment and reporting, including reporting in subpopulations, according to Risk of Bias

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/peripheral-manifestations-in-axial-and-peripheral-spondyloarthritis-a-systematic-literature-review-on-their-assessment-in-clinical-trials/