Methotrexate and/or Etanercept Improves Dactylitis, Nail Disease in Early PsA

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The analysis determined improvement based on a variety of clinical assessments, including the Leeds Enthesitis Index (LEI), Leeds Dactylitis Index (LDI), and modified Nail Psoriasis Severity Index (mNAPSI) scores, at baseline and week 24.

The Study of Etanercept and Methotrexate in Combination or as Monotherapy in Subjects with Psoriatic Arthritis (SEAM-PsA) analyzed the impact of enthesitis, dactylitis, nail disease, and psoriasis on the treatment response in patients with early PsA. Results indicated that the presence of dactylitis and nail disease were associated with improved outcomes in this patient population, according to a study published in RMD Open.1

“PsA is associated with considerable disease burden as patients experience several symptoms, including peripheral and axial joint inflammation, enthesitis, dactylitis, nail disease, and psoriasis,” investigators stated. “The influence of these clinical domains on treatment response to methotrexate or tumor necrosis factor (TNF) inhibitors as monotherapy or in combination in PsA is not known.”
The post hoc analysis determined improvement based on assessments of the Enthesitis Index (EI), Leeds Enthesitis Index (LEI), Leeds Dactylitis Index (LDI), Spondyloarthritis Research Consortium of Canada (SPARCC), modified Nail Psoriasis Severity Index (mNAPSI) scores, and body surface area (BSA) using the pooled SEAM-PsA population data. Outcomes of minimal disease activity (MDA) responses, Psoriatic Arthritis Disease Activity Score (PASDAS) low disease activity (LDA), PASDAS changes, and Good Responses and Disease Activity Index for Psoriatic Arthritis (DAPSA) scores were collected at baseline and week 24. Eligible patients had active PsA with with ≥3 tender and ≥3 swollen joints, an active psoriatic skin lesion, and were naïve to methotrexate and biological therapies. Patients were randomized to receive oral methotrexate 20 mg, subcutaneous etanercept 50 mg, or combination therapy.

Ultimately, 851 patients (methotrexate monotherapy, n=284; etanercept monotherapy, n=284; combination therapy, n=283) were included in the phase 3, randomized controlled trial, SEAM-PsA (NCT02376790). The mean age was 48.4 years, mean disease duration was 3.2 years, 90.7% of patients were White, and 50,8% were women.

Dactylitis at baseline (LDI>0 vs LDI=0) was associated with improved MDA (OR: 1.4, p=0.0457), PASDAS LDA (OR: 1.8, p=0.0014), and Good Responses (OR: 1.6, p=0.0101), as well as reductions in PASDAS (estimate: –0.9, p<0.0001) and DAPSA scores (estimate: –3.8, p=0.0155) at the end of the week 24. Further, improvements in baseline nail disease (mNAPSI >1 vs mNAPSI≤1) were reported in MDA (OR: 1.8, p=0.0233) and PASDAS LDA (OR: 1.8, p=0.0168) responses, and a reduction in PASDAS (estimate: –0.7, p=0.0005). However, improvements in enthesitis (SPARCC EI>0 vs SPARCC EI=0 or LEI>0 vs LEI=0) were not reported.

Utilizing the large data set from the SEAM-PsA trial to address disease activity and outcomes in patients with PsA strengthened the study. However, the lack of generalizability is a potential limitation, as patients enrolled were treatment-naïve and may not be an accurate representation of the experience of patients with moderate-to-severe PsA. Lastly, the impact of individual treatment on predictors of response were not accounted for as the analysis was based on pooled data from patients receiving methotrexate and/or etanercept.

“Further research is needed to confirm the preliminary findings that presence of dactylitis and to some extent nail disease but not enthesitis or psoriasis-affected BSA, may be predictive of improved outcomes in patients with early PsA treated with methotrexate and/or etanercept,” investigators concluded.


Helliwell PS, Mease PJ, Kavanaugh A, et al. Impact of clinical domains other than arthritis on composite outcomes in psoriatic arthritis: comparison of treatment effects in the SEAM-PsA trial. RMD Open. 2022;8(2):e002366. doi:10.1136/rmdopen-2022-002366