PASDAS Sensitive at Detecting Changes in Psoriatic Disease Activity

Laura Coates, MBChB, MRCP, PhD

Among measures examined to detect changes in psoriatic disease activity, the Psoriatic Disease Activity Score (PASDAS) is the most sensitive and has the highest ability, according to new study findings presented at the Congress of Clinical Rheumatology 2020 meeting.

The findings could inform the planning of future studies that use composite measures to evaluate psoriatic arthritis therapies.

Laura Coates, MBChB, MRCP, PhD, and investigators examined the relative performance of 5 continuous composite measures— Disease Activity Score 28 (DAS28), Clinical Disease Activity Index (CDAI), Simplified Disease Activity Index (SDAI), Disease Activity Index in PsA (DAPSA), and PASDAS—used in a phase 3, randomized trial in patients with psoriatic arthritis that compared methotrexate monotherapy with etanercept monotherapy and with a combination of the 2.

The phase 3 trial, “The Study of Etanercept And Methotrexate in Combination or as Monotherapy in Subjects with Psoriatic Arthritis,” was a 48-week, double-blind, randomized, multicenter, international, controlled trial. Eligible patients were at least 18 years old with active psoriatic who were naïve to etanercept and other biologic agents. The patients had at least 3 tender and at least 3 swollen joints.

Patients were randomized 1:1:1 to weekly treatments of either oral methotrexate monotherapy plus subcutaneous placebo, subcutaneous etanercept monotherapy plus oral placebo, or combination therapy of subcutaneous etanercept plus oral methotrexate. Methotrexate doses were initiated at 10 mg/week and titrated up to 20 mg/week over 4 weeks. Etanercept was administered at 50 mg/week.

There were mean improvements from baseline to week 24 in DAS28-CRP, CDAI, and SDAI. Of the patients enrolled, 691 completed the trial. More patients achieved ACR, Minimal Disease Activity, and Very Low Disease Activity responses at week 24 in the etanercept-containing groups compared with methotrexate alone. There were greater mean changes in DAS28-CRP and PASDAS continuous composite measures from baseline to week 24 in the etanercept groups compared with methotrexate monotherapy. The mean changes from baseline to week 24 for CDAI, SDAI, and DAPSA were similar among all groups but slightly higher in the etanercept groups.

For all 5 continuous composite measures, the etanercept groups had numerically larger effect sizes and standardized responses than methotrexate monotherapy. PASDAS had the most pronounced difference between the etanercept groups and methotrexate monotherapy.

Changes in tender and swollen joint counts were the main drivers of changes in composite scores for DAPSA, DAS28-CRP, CDAI, and SDAI. The main driver of changes in the PASDAS score was in the Physician Global Assessment and the Patient Global Assessment.

Coates and the team noted measures that covered multiple domains, like PASDAS, might be optimal for quantifying psoriatic arthritis disease burden as they showed the greatest sensitivity to change and better represented the breadth of disease manifestations.

The study, “The Performance Characteristics of Composite Measures Used in a Randomized Trial Examining Etanercept and Methotrexate as Monotherapy or in Combination in Patients With Psoriatic Arthritis,” was published as part of the Congress of Clinical Rheumatology 2020 meeting.