BASDAI and ASDAS Compared in Assessing Axial Involvement in Patients With PsA

In patients with psoriatic arthritis (PsA) receiving treatment with guselkumab, the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Ankylosing Spondylitis Disease Activity Score (ASDAS) performed similarly in evaluating symptoms of axial involvement, according to results of a post hoc analysis presented at the American College of Rheumatology (ACR) Convergence 2022, held between November 10 and 14, in Philadelphia, Pennsylvania.

It is well known that only 1 of the questions on the BASDAI is specific to axial symptoms, whereas the ASDAS excludes the evaluation of enthesitis, gives less preference to peripheral activity, and is considered more objective than the BASDAI.

Participants, enrolled in the DISCOVER-1 and -2 trials, included adults with active PsA despite the use of standard therapies. Participants enrolled in DISCOVER-1 had at least 3 swollen joints (SJC), at least 3 tender joints (TJC), and C-reactive protein (CRP) levels of at least 0.3 mg/dL, whereas those in DISCOVER-2 had SJC of at least 5, TJC of at least 5, and CRP levels of at least 0.6 mg/dL.

Axial PsA was identified by the presence of sacroiliitis based on radiographic or magnetic resonance imaging (MRI) scans. Additional measurement tools included the Functional Assessment of Chronic Illness Therapy (FACIT)-fatigue, the Leeds Enthesitis Index (LEI), patient pain, patient global, and physician global.

Participants were randomly assigned 1:1:1 to receive guselkumab 100 mg every 4 weeks, guselkumab 100 mg at week 0, at week 4, and then every 8 weeks; or placebo, with crossover to guselkumab every 4 weeks at week 24.

A total of 436 patients (312 with axial PsA and 124 without axial PsA) with available baseline BASDAI information were enrolled in the study. Overall, 31% of the participants in DISCOVER-1 received treatment with 1 to 2 tumor necrosis factor (TNF) inhibitors; participants in DISCOVER-2 were biologic-naive.

Among participants with axial PsA, BASDAI demonstrated a weak association with SJC, TJC, LEI, and physician global; a moderate correlation with fatigue; and a strong association with patient global and patient pain (P <.05). Similar results were reported with ASDAS, as well as with modified versions of the BASDAI and the ASDAS.

Among individuals without axial PsA, associations of the BASDAI and the ASDAS with SJC, TJC, and LEI remained weak, whereas correlations with patient global and patient pain remained strong pain (P <.05). Longitudinally, among patients with and without baseline enthesitis, LEI and SJC, respectively, demonstrated significant but not clinically important associations with each outcome.

Further, the presence of axial disease was associated with significantly greater BASDAI and ASDAS scores at baseline and longitudinally, with no differences in the incremental effect on BASDAI, normalized ASDAS, or the modified versions.

The researchers concluded that the BASDAI and ASDAS performed similarly, with both showing weak correlations with peripheral arthritis and moderate/strong associations with fatigue and pain.

“These results suggest that both BASDAI and ASDAS are valid, and perform comparably in assessing activity of axial disease in [patients with PsA],” they added.

Disclosure: Some of the study authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.