Relationship between skin severity and PASDAS in PsA: A cross-sectional study in the BSR-PsA and GRACE cohorts

Psoriatic arthritis (PsA) is a heterogeneous inflammatory condition. Although several PsA-specific measures exist, there is a lack of consensus regarding an optimal measure for assessing PsA activity. The PASDAS includes a broad spectrum of PsA domains, including arthritis, enthesitis, dactylitis, CRP levels, physician and patient global VAS scores, and patient-reported physical function. Additionally, it is responsive to other PsA-specific measures. However, the extent to which PASDAS captures skin involvement is unknown.

A cross-sectional study exploring the relationship between skin severity and PASDAS in PsA with the aim of determining the utility of PASDAS as a comprehensive measure for assessing PsA disease activity was published by Mulder et al. in Rheumatology.¹ The study included data at baseline from patients with PsA in the British Society for Rheumatology PsA register (BSR-PsA; n = 1,126) and Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) Composite Exercise (GRACE; n = 588) cohorts.

Key learnings

PASDAS, and physician and patient global VAS scores as measured by BSA and DLQI increased with worsening skin disease severity in both the BSR-PsA and GRACE cohorts (p ≤ 0.001, each).

Severe skin disease was associated with higher PASDAS (p = 0.03), VAS physician (p = 0.001), VAS patient (p = 0.007), and DLQI scores (p = 0.005) vs less severe skin disease among propensity-matched patients in the BSR-PsA cohort (n = 30).

Age (p = 0.04), and higher VAS physician (p = 0.001), VAS patient (p = 0.01), and DLQI scores (p < 0.001) were associated with severe skin involvement vs less severe skin involvement among the propensity-matched patients in the GRACE cohort (n = 65).

Though there is a lack of formal skin domain, PASDAS captures skin disease activity in PsA, likely through physician and patient global VAS scores. The findings support PASDAS application as a composite measure in both routine clinical practice and clinical trials.