The Long View of Diagnostic Delay in Axial Spondyloarthritis Save

Axial spondyloarthritis (axSpA) remains a diagnostic challenge, particularly in its early stages before structural sacroiliitis is visible on imaging. At ACR 2025, Abstract #1407 presented a cross-sectional analysis from the Brazilian Spondyloarthritis Registry (RBE), offering a unique perspective on how diagnostic patterns have evolved over six decades.

The study included 791 patients diagnosed with axSpA across 19 rheumatology centres in Brazil. All patients met the ASAS classification criteria and were grouped by the decade in which their first spondyloarthritis-related symptom occurred, spanning from 1961 to 2024.

One of the most striking findings was the dramatic reduction in diagnostic delay over time. In the 1960s, the mean delay from symptom onset to diagnosis was 41.7 years. By the 2020–2024 period, this had dropped to just 1.9 years. This improvement was consistent across sexes, with no significant difference in delay between men and women in any decade. While men remained the majority overall (69.2%), female representation increased steadily from 30% in the 1970s to 50 percent in the 2020s.

The study also highlighted a shift in disease subtype recognition. Before 2009, all cases were classified as radiographic axSpA (r-axSpA). By 2020–2024, non-radiographic axSpA (nr-axSpA) accounted for 16.7% of diagnoses. Both subtypes showed significant reductions in diagnostic delay, reflecting the impact of magnetic resonance imaging (MRI) and updated classification criteria.

Low back pain remained the dominant initial symptom across all decades, reported by 81 to 90% of patients. However, men were significantly more likely to report hip pain than women (23.2 vs. 8.6%). Other symptoms, including upper-limb arthritis, dactylitis, cervical pain, and buttock pain, were similar between sexes. Notably, hip pain was more common in nr-axSpA than in r-axSpA (23.2 vs. 8.2%), suggesting that early inflammatory changes may present differently depending on disease subtype.

These findings underscore the progress made in axSpA recognition, likely driven by increased awareness, broader use of MRI, and more inclusive classification criteria. The growing proportion of nr-axSpA diagnoses reflects a shift toward earlier detection, even in the absence of radiographic changes.

For clinicians, this study reinforces the importance of maintaining a high index of suspicion for axSpA in patients with chronic back pain, especially when symptoms improve with activity and worsen with rest. For health systems, it highlights the need for accessible imaging, timely referral pathways, and continued education to ensure early and equitable diagnosis.