Axial spondyloarthritis

Looking for the plain-language version? See the patient version of this page.

Understanding this condition

What it is

Chronic inflammatory arthritis of the axial skeleton spanning non-radiographic axSpA and radiographic axSpA (ankylosing spondylitis). It is associated with HLA-B27 and with uveitis, psoriasis, and inflammatory bowel disease.^[1]

Symptoms

Inflammatory back pain of insidious onset before age 45, with prolonged morning stiffness, improvement with exercise rather than rest, and night pain. Peripheral arthritis, enthesitis, dactylitis, and extra-musculoskeletal features may accompany it. The formal ASAS inflammatory-back-pain and classification criteria are described in the classification callout and are not transcribed here pending their primary sources.

Who gets it

Onset is typically before age 45 and affects both sexes. There is a strong HLA-B27 association and familial clustering. Adult prevalence is approximately 0.1 to 0.5 percent. axSpA can also begin in childhood or adolescence (juvenile axSpA), which has its own separate 2026 guidance.^[1]

How it is diagnosed

Diagnosis is clinical, supported by inflammatory back pain, HLA-B27, elevated CRP or ESR, and imaging. In adults, an AP pelvis radiograph is the preferred initial imaging test; where radiography is non-diagnostic, MRI of the sacroiliac joints without contrast is conditionally recommended (over MRI lumbar spine, low-dose CT, bone scan, or PET), with standardized reporting and an experienced reader favored. Classification uses the ASAS criteria and, for radiographic disease, the modified New York criteria (see the classification callout). Historically there has been a long diagnostic delay (an average of roughly 8 to 11 years from symptom onset), which the emphasis on inflammatory back pain, HLA-B27, and SIJ MRI aims to shorten.^{[2, 3]}

When diagnosis takes time, and being believed

Diagnostic delay is common and well recognised in axSpA, and patients frequently report feeling disbelieved before diagnosis. A patient-centred approach, taking the history seriously, maintaining a low threshold to investigate inflammatory back pain including in those with normal radiographs, and following the patient until the picture is clear, matters both diagnostically and for the therapeutic relationship.

What to expect over time

The course varies from mild to progressive spinal ankylosis, with radiographic progression in a minority over years; in research cohorts, a change in the extent of spinal damage was detectable in about 20 to 35 percent of patients with ankylosing spondylitis over a 2-year interval. Early and sustained inflammation control and exercise are the mainstays.^[1]

Living with and treating it

Goals of treatment

Goals are to control symptoms and inflammation, preserve function and spinal mobility, and manage extra-musculoskeletal manifestations. Disease activity is monitored at regular intervals with a validated axSpA measure (ASDAS or BASDAI) and CRP or ESR. A formal treat-to-target strategy is conditionally recommended against; the 2026 update conditionally recommends a goal of low disease activity.^{[1, 2]}

Treatment options

See the treatment ladder. NSAIDs and physical therapy come first (both strongly recommended); then a TNF inhibitor or an IL-17 inhibitor (equal in 2026) or a JAK inhibitor; conventional synthetic DMARDs are reserved for peripheral or extra-musculoskeletal disease; systemic glucocorticoids are recommended against, while a local glucocorticoid injection may be used for isolated sacroiliitis or peripheral arthritis.^{[1, 2]}

Tests and monitoring

Monitor with a validated axSpA disease-activity measure (ASDAS or BASDAI) and CRP or ESR at regular intervals. Routine repeat spine radiographs at scheduled intervals are recommended against. Spine or SIJ MRI is suggested when activity is unclear on a b/tsDMARD, and MRI is recommended against to confirm inactivity. Drug-specific laboratory monitoring is on each medicine's guide.^{[1, 2]}

Flares

Flares are managed by optimizing NSAIDs and confirming adherence and exercise; frequent or severe flares prompt escalation per the ladder. New or recurrent extra-musculoskeletal manifestations (uveitis, IBD, psoriasis) should be assessed and may redirect therapy.^[2]

Living well

Exercise and physical therapy are central (physical therapy is strongly recommended), with supervised active exercise favored and both aquatic and land-based approaches supported. Counsel on weight, cardiovascular risk screening, depression, and bone health (fall evaluation is strongly recommended and DXA screening is conditionally recommended). Spinal manipulation is strongly recommended against in axial spondyloarthritis (2026 ACR/SAA/SPARTAN update, recommendation 47.1: strong recommendation against, very low quality evidence); the fracture risk is heightened with spinal fusion or advanced osteoporosis.^{[1, 2]}

Related conditions

Screen for uveitis and inflammatory bowel disease by history (strong recommendations) and co-manage with ophthalmology, gastroenterology, or dermatology as relevant. For recurrent uveitis or IBD, TNF-inhibitor monoclonal antibodies are favored over other biologics; for psoriasis, IL-17 inhibitors are favored. Routine cardiac conduction (ECG) and valvular (echocardiogram) screening are recommended against without an indication. Osteoporosis is addressed with DXA screening and fall evaluation.^{[1, 2]}

What to expect at your appointment

First visit: characterize inflammatory back pain and extra-musculoskeletal history (uveitis, IBD, psoriasis) and family history; check HLA-B27 and CRP or ESR and obtain sacroiliac-joint imaging; establish a baseline disease-activity measure and an exercise or physical-therapy plan; and screen for extra-musculoskeletal manifestations and bone health.^[2]

SpA features and their ASAS definitions (each feature counts once)

The SpA-feature definitions above and the imaging anchors are transcribed from the primary ASAS publication (Rudwaleit et al, Ann Rheum Dis 2009;68:777 to 783; conflict-of-interest correction 2019;78:e59). Sacroiliitis on radiographs means bilateral grade 2 to 4 or unilateral grade 3 to 4 changes by the modified New York criteria; active sacroiliitis on MRI means definite bone marrow oedema or osteitis typical of SpA. Elevated CRP counts as a SpA feature only in the context of back pain. The full modified New York criteria (van der Linden 1984) and the ASAS peripheral SpA criteria (2011) are referenced but not transcribed here. These are classification, not diagnostic, criteria.

Treatment ladder

1. 1

   First step

   First-line: NSAIDs (strongly recommended), with continuous dosing preferred in active disease, plus physical therapy (strongly recommended). Systemic glucocorticoids are recommended against; a local glucocorticoid injection may be used for isolated sacroiliitis or peripheral arthritis.

   NSAID responsiveness is judged after adequate trials of at least two NSAIDs (2019).

2. 2

   If NSAIDs are not enough

   For active disease despite NSAIDs, add a biologic: a TNF inhibitor or an IL-17 inhibitor, each strongly recommended and considered equal in the 2026 update (the 2019 guideline conditionally preferred a TNF inhibitor first). Conventional synthetic DMARDs are not recommended for axial disease.

   Extra-musculoskeletal manifestations steer the choice: acute anterior uveitis or IBD favors a TNF-inhibitor monoclonal antibody; psoriasis favors an IL-17 inhibitor.

3. 3

   If the first biologic does not work

   If the first b/tsDMARD is ineffective, switch to an agent with a different mechanism of action; a JAK inhibitor is strongly recommended as an option, although TNF inhibitors and IL-17 inhibitors are each conditionally preferred over JAK inhibitors. After failure of two or more classes, re-evaluate for reasons for non-response (adherence, nociplastic pain, diagnosis).

   Primary versus secondary non-response guides whether to switch class or within class (2019).

4. 4

   Peripheral or resistant disease

   For persistent peripheral arthritis or uncontrolled extra-musculoskeletal manifestations, a conventional synthetic DMARD (for example sulfasalazine or methotrexate) may be added; in selected refractory cases, dose escalation or dual-targeted therapy can be considered.

   Sulfasalazine and methotrexate have a role for peripheral arthritis, not for axial disease (2019).

Guideline recommendations

Key points

Medication guides

Plain-language guides to the medicines used for this condition. Each has a patient and a clinician view.

• NSAIDs
• TNF inhibitors
• IL-17 inhibitors
• JAK inhibitors
• Sulfasalazine
• Methotrexate
• Glucocorticoids

References

1. Ward MM, Deodhar A, Gensler LS, et al. 2019 Update of the American College of Rheumatology/Spondylitis Association of America/Spondyloarthritis Research and Treatment Network Recommendations for the Treatment of Ankylosing Spondylitis and Nonradiographic Axial Spondyloarthritis. Arthritis Rheumatol. 2019;71(10):1599-1613. doi:10.1002/art.41042 https://doi.org/10.1002/art.41042
2. 2026 Update of the American College of Rheumatology/Spondylitis Association of America/Spondyloarthritis Research and Treatment Network Recommendations for the Treatment of Axial Spondyloarthritis in Adults and Children/Adolescents. American College of Rheumatology; guideline summary approved by the ACR Board of Directors 31 May 2026. Full manuscripts to be published in Arthritis & Rheumatology and Arthritis Care & Research. https://rheumatology.org/axial-spondyloarthritis-guideline
3. Rudwaleit M, van der Heijde D, Landewe R, et al. The development of Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis (part II): validation and final selection. Ann Rheum Dis 2009;68(6):777 to 783. doi:10.1136/ard.2009.108233 (correction Ann Rheum Dis 2019;78(6):e59, doi:10.1136/ard.2009.108233corr1) https://doi.org/10.1136/ard.2009.108233