Joint Location Influences Response to TNF Inhibitor in PsA

TOPLINE:

The response time to tumour necrosis factor (TNF) inhibitors in patients with psoriatic arthritis is influenced by the location of the affected joint. The shoulder and elbow joints exhibit higher swelling resolution, whereas the wrist, third-digit, and knee joints show lower resolution.

METHODOLOGY:

• Researchers conducted a retrospective observational cohort study using prospectively collected data from nine European registries within the European Spondyloarthritis network to evaluate the response to a first TNF inhibitor across different joint locations in patients with psoriatic arthritis.
• A total of 1729 bionaive patients with psoriatic arthritis (mean age, 49.4 years; 54% women) who had at least one swollen joint (8397 swollen joints) at the start of their first TNF inhibitor — either as monotherapy or combined with methotrexate — were included.
• Information on swollen and tender joints at baseline was on the basis of the 28-joint count, with data on the proportion of patients with involvement of small joints (finger joints or wrists) and large joints (shoulder, elbow, or knee joints).
• Clinical assessments were performed at follow-up visits at 6-, 12-, 18-, and 24 months after starting the first TNF inhibitor.
• The primary outcome was the time to the first resolution of clinical synovitis, defined as the first documented absence of clinical joint swelling after treatment initiation in the initially swollen joints.

TAKEAWAY:

• Resolution of synovitis was noted for 67% of swollen joints, with a duration to resolution of 189 days. Clinical synovitis resolved in more than 75% of the joints evaluated at all sites within the first 6 months.
• In the upper limb, the rates of resolution of joint swelling were higher for the shoulder (adjusted hazard ratio [aHR], 1.65; 95% CI, 1.16-2.35) and elbow (aHR, 1.90; 95% CI, 1.38-2.61) but lower for the wrist (aHR, 0.72; 95% CI, 0.62-0.83) than for the joints of digit 3.
• Within the fingers, significantly higher rates of resolution were noted for the joints of digits 1, 2, 4, and 5 than for the joints of digit 3, with the highest estimates of resolution observed in digits 4 (aHR, 1.77; 95% CI, 1.49-2.11) and 5 (aHR, 1.88; 95% CI, 1.53-2.31).
• The knee showed a lower rate of resolution of joint swelling than the elbow (aHR, 0.56; 95% CI, 0.40-0.78).

IN PRACTICE:

“The observation that the rate of synovitis resolution was lower for the knee, the sole weight-bearing joint in the 28-joint count, compared to the elbow, could suggest that joints more susceptible to mechanical stress respond less effectively to TNFi [TNF inhibitors],” the authors wrote. “Our analysis suggests that the clinical response to TNFi treatment in PsA with regards to peripheral arthritis is influenced by the specific location of the affected joint,” they added.

SOURCE:

The study was led by Adrian Ciurea, University Hospital Zurich, University of Zurich, Zurich, Switzerland. It was published online on January 31, 2025, in Arthritis Research & Therapy.

LIMITATIONS:

Data on individual joints were available only for a subgroup of patients in the EuroSpA research network. The Disease Activity Score 28 response criteria, validated for psoriatic arthritis, might not have been suitable for patients with oligoarticular disease. The study did not provide details on the use of local steroid injections at specific joints or systemic glucocorticoids before and after starting TNF inhibitor treatment.

DISCLOSURES:

This study and the EuroSpA Research Collaboration Network were supported by Novartis. Several authors reported receiving grants, speaking fees, or consulting fees, serving on advisory boards, or having other financial ties with several organisations and pharmaceutical companies, including Novartis.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.