← Questions/GETTING A DIAGNOSIS
Why did it take so long to get diagnosed?
The short answer
The delay between first symptoms and a diagnosis is typically several years, and in some countries over a decade, because back pain is common, the early signs are easy to put down to something mechanical, and the scans can be read either way. A third of local diagnoses were overturned when experts re-read the scans in one large study, in both directions. Referral rules built on the features that actually predict AS, and tighter definitions of what counts as a positive MRI, are the two changes aimed squarely at this.
6 papers behind this answer, best first
Clicking through to a study? How to read a paper is the ten-minute version.
Spondyloarthritis Research and Treatment Network Recommendations for the Referral of Adults With Chronic Back Pain and Suspected Axial Spondyloarthritis to a Rheumatologist.
ACR open rheumatology
US experts and patients built a points-based referral rule for adults under 45 with chronic back pain: features such as uveitis, raised inflammatory markers, a family history, HLA-B27, inflammatory bowel disease, imaging signs, psoriasis and a good response to anti-inflammatories each add to a score, and three or more points means see a rheumatologist. It targets a diagnostic delay that in the US runs up to 14 years.
Enhancing diagnostic accuracy in axial spondyloarthritis through centralised clinical and imaging evaluation: results from a prospective multicentre project.
Annals of the rheumatic diseases
When 969 suspected cases of axial spondyloarthritis were re-reviewed by a central expert panel, a third of the local diagnoses were overturned, usually because imaging had been over-read and the back pain was mechanical, while most local rulings-out were confirmed. Misdiagnosis in both directions is common enough that a second expert look at the scans is worth asking for when the diagnosis feels uncertain.
What Defines an MRI Considered Indicative of Axial Spondyloarthritis in the Sacroiliac Joints: A Systematic Literature Review.
The Journal of rheumatology
Reviewing 30 studies, the authors found the usual MRI sign of axial spondyloarthritis, bone marrow swelling in the sacroiliac joints, also shows up in healthy people and women after childbirth, while erosion and fat change next to that swelling are far more specific. MRI definitions are being tightened, which should mean fewer wrong diagnoses in both directions.
Biomarkers in axial spondyloarthritis diagnosis: from clinical signs to multi-omics integration.
Frontiers in immunology
This review maps every kind of marker used to diagnose axial spondyloarthritis, from HLA-B27 and CRP through genomics and metabolomics to MRI read by deep-learning models, and how combining them is starting to shorten the typical two-to-six-year wait for a diagnosis. For anyone who waited years, it explains why, and what is changing.
Lower HLA-B27 positivity and heterogeneous late-onset case proportions across axial spondyloarthritis cohorts: a systematic review and meta-analysis.
Rheumatology international
Pooling 42 studies, about one in eight people with axial spondyloarthritis first had symptoms after age 45, and those late starters were half as likely to carry the HLA-B27 gene. If you were diagnosed later in life and tested HLA-B27 negative, that is a recognised pattern, not an oddity.
Automated detection of active and structural MRI lesions in the sacroiliac joints in axial spondyloarthritis: training and validation across 3 phase III clinical trial datasets.
Annals of the rheumatic diseases
A deep-learning system trained on one secukinumab trial and tested on two others detected fusion, erosion and fat changes in sacroiliac joint MRIs about as well as expert readers agree with each other, with active inflammation the hardest to call. Automated reading of these scans is approaching clinical quality, which could shorten the queue for a confident diagnosis.
Plain-language guides on this from patient organisations
Reviewed sources written for patients. They cover the “what do I do” part that research papers can’t.
- SAA: Could I have spondyloarthritis? screening tool ↗
Spondylitis Association of America
- CreakyJoints Australia: 12 myths about axial spondyloarthritis ↗
CreakyJoints Australia, 2023
- NHS: How AS is diagnosed ↗
NHS (UK)
- healthdirect: Ankylosing spondylitis ↗
healthdirect (Australian Government), reviewed March 2025