Hidden Late-Onset SpA in PMR: Who Are These Patients?

TOPLINE:

Patients initially diagnosed with polymyalgia rheumatica (PMR) but later reclassified as having spondyloarthritis (SpA) showed bone marrow edema of the spine and sacroiliac joints on MRI. They also responded poorly to glucocorticoid therapy or were unable to taper off steroids and were more likely to benefit from treatment using TNF inhibitors or interleukin-17 (IL-17) inhibitors.

METHODOLOGY:

• Researchers at a hospital in Leeds, England, screened patients with psoriatic arthritis or axial SpA to identify those who were initially diagnosed with PMR from 2002 to 2024.
• They analyzed the data of 31 patients (median age, 62 years; 17 women) who fulfilled standard diagnostic criteria for PMR and were subsequently diagnosed with SpA.
• Conventional radiography, MRI of the spine and sacroiliac joints, and FDG PET-CT were performed to confirm a diagnosis of SpA in patients with PMR and to exclude those with other conditions.

TAKEAWAY:

• Among the 31 patients, 12 (38.7%) were diagnosed with SpA within 3 months of initial presentation, whereas the remaining 19 (61.3%) received their diagnosis after a median follow-up duration of 3 years due to persistent musculoskeletal symptoms and failure to taper glucocorticoids. The presence of psoriasis and a family history of SpA were associated with an early diagnosis of SpA.
• On MRI, bone marrow edema — a hallmark of SpA — was evident in the sacroiliac joints of 17 patients, the spine of 15 patients, and both sites in 20 patients.
• Symptoms of PMR completely resolved in 21 of 31 patients following initial glucocorticoid therapy, whereas 10 patients showed a clinically partial response to glucocorticoid therapy. Additionally, seven of the 21 initial responders experienced disease flares during follow-up (median duration, 5 years).
• During follow-up, one third of the patients were started on biologics such as anti-TNF-alpha and anti-IL-17 agents, both of which are recommended first-line treatments for axial SpA; at the last visit, eight patients were receiving conventional disease-modifying antirheumatic drugs, and 11 were receiving biologics.

IN PRACTICE:

“In PMR cases with refractory symptoms or difficult GC [glucocorticoid] reduction, these findings raise the possibility that MRI may have a role in more accurate identification of a subset of PMR/SpA overlap, with potential treatment implications,” the authors wrote.

SOURCE:

The study was led by Kerem Abacar, MD, Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Chapel Allerton Hospital, Leeds. It was published online on July 22, 2025, in Arthritis & Rheumatology.

LIMITATIONS:

This study did not discuss any limitations.

DISCLOSURES:

No financial support was received for this study. Some authors declared receiving grants, contracts, consulting fees, payments or honoraria, and support for attending meetings or having other ties with various pharmaceutical companies.

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