Patients with severe psoriatic arthritis and extensive psoriasis (Cluster 3) showed the largest improvements in treatment response, according to a recent study.

In the real-world longitudinal study from the Psoriatic Arthritis Research Consortium, published in Annals of the Rheumatic Diseases, investigators identified three distinct phenotype clusters of psoriatic arthritis (PsA) based on disease severity and psoriasis involvement. Among 627 participants, Cluster 1 (47.4%) was characterized by mild PsA and psoriasis, Cluster 2 (34.3%) by severe PsA with mild psoriasis, and Cluster 3 (18.3%) by severe PsA with extensive psoriasis. Treatment response was assessed in 339 patients initiating or changing therapy, with Cluster 3 showing the greatest improvements in disease activity (clinical Disease Activity in Psoriatic Arthritis [cDAPSA]) and impact (Psoriatic Arthritis Impact of Disease [PsAID]) scores.

Patients in Cluster 3 demonstrated a median reduction of −6.5 in cDAPSA and −1.3 in PsAID, with 14.5% achieving cDAPSA remission and 27.4% reaching a PsAID score of 4 or lower. In comparison, Clusters 1 and 2 showed smaller improvements. Although patients in all clusters received tumor necrosis factor (TNF) inhibitors, there were no statistically significant differences in treatment outcomes among the clusters when TNF inhibitors were initiated.

The findings emphasized the heterogeneity of PsA and the pivotal role of both psoriasis and musculoskeletal severity in treatment response. While the clusters were generally stable over time, transitions from Cluster 3 to milder clusters suggested that treatment may influence disease progression. The results highlighted the need for personalized treatment strategies and more sensitive outcome measures to better capture the full spectrum of PsA activity.

Full disclosures can be found in the published study.