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Axial spondyloarthritis

Last updated 28 Mar 2026

Introduction

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease affecting the spine and sacroiliac joints, with strong association to HLA-B27 positivity. The condition encompasses both radiographic (ankylosing spondylitis) and non-radiographic presentations. Early diagnosis and treatment initiation are critical to prevent structural damage and maintain function.

Epidemiology and Genetics

HLA-B27 positivity is present in 90% of axSpA patients. Disease typically presents in the third to fourth decade. Male predominance noted (3:1 ratio). Environmental triggers and bacterial infections may precipitate disease in genetically susceptible individuals.

Pathophysiology

Inflammatory Cascade

TNF-alpha plays a central role in the inflammatory process, driving immune cell recruitment to the enthesis and spinal ligaments. IL-17 signalling promotes osteoblast activation and new bone formation (syndesmophytes), leading to spinal fusion. HLA-B27 presentation of bacterial peptides is thought to cross-react with self-antigens, perpetuating autoimmunity.

Structural Changes

Characteristic lesions occur at the enthesis. Inflammation leads to bone erosion, followed by new bone formation and syndesmophyte bridging of vertebrae, causing progressive ankylosis and spinal rigidity.

Clinical Presentation

Axial Symptoms

Chronic back pain starting in sacroiliac region, typically worse in early morning (>30 minutes). Stiffness and restricted spinal mobility progressive over months to years. Pain improves with activity and exercise, worsens with rest.

Extra-Articular Manifestations

  • Acute anterior uveitis (25-30% of patients)
  • Inflammatory bowel disease (10-15%)
  • Skin manifestations (psoriasis, pustulosis)
  • Cardiac conduction abnormalities
  • Pulmonary fibrosis (rare, late disease)

Investigations

  • Essential
    HLA-B27 Testing
    Positive in ~90% of patients. Diagnostic support only; not required for diagnosis.
  • Essential
    Inflammatory Markers (ESR/CRP)
    Assess disease activity. May be normal in 20-30% of patients.
  • Essential
    Pelvic Radiographs
    Bilateral sacroiliitis on plain X-ray diagnostic of radiographic disease. Grade 2 or higher bilaterally required.
  • Essential
    Spinal MRI
    Superior to X-ray for early detection of inflammation (STIR sequences). Osteitis and syndesmophytes visible.
  • Available
    BASDAI / ASDAS Scores
    Validated composite disease activity scores. ASDAS incorporates CRP/ESR, back pain, morning stiffness, function. More sensitive to change.

Disease Severity Assessment

MILD
Low Disease Activity
BASDAI <4, ASDAS <1.3. Isolated back pain, normal function.
NSAIDs; exercise; monitoring
MODERATE
Moderate Activity
BASDAI 4–6, ASDAS 1.3–2.1. Progressive symptoms, functional limitation.
Optimise NSAIDs; consider biologic referral
SEVERE
High Disease Activity
BASDAI >6, ASDAS >2.1. Significant impairment, radiographic damage.
Biologic therapy essential; specialist rheumatology

Treatment Strategy

Non-Pharmacological Management

Physiotherapy and exercise are essential and should be core to all treatment. Regular spinal mobility exercises, posture education, and stretching reduce stiffness. Aquatic therapy often preferred. Smoking cessation strongly advised as it increases inflammation and radiographic progression risk.

First-Line Pharmacotherapy: NSAIDs

NSAIDs are first-line agents for symptomatic relief and may slow radiographic progression. Continuous use more effective than on-demand. At least 2–3 weeks trial required to assess efficacy.

💊
Indomethacin
Indocid® · NSAID
Adult Dose50–150 mg daily in divided doses
RouteOral
DurationContinuous; ongoing
NotesCaution if eGFR <30; use with gastroprotection (PPI).
PBS Status✓ PBS Listed

Biologic Therapy

TNF Inhibitors

Indicated for inadequate response to NSAIDs or for severe/active disease. Adalimumab and etanercept are first-line biologic agents with strong efficacy in axSpA. Slow radiographic progression and improve ASDAS/BASDAI scores. Requires TB screening and vaccination prior to initiation.

💉
Adalimumab
Humira®, Idacio® · TNF-α Inhibitor
Adult Dose40 mg SC every 2 weeks
RouteSubcutaneous injection
MonitoringTB screen before initiation; FBC, LFTs 6-weekly for first 3 months
PBS Status✓ PBS Listed
💉
Secukinumab
Cosentyx® · IL-17A Inhibitor
Adult Dose300 mg loading (weekly × 4), then 300 mg monthly
RouteSubcutaneous injection
NotesPreferred if concomitant psoriasis or TNF-i intolerance. Monitor for candida infections.
PBS Status✓ PBS Listed

Switching Biologics

If inadequate response after 12 weeks of TNF-i at optimal dose, switch to IL-17i or second TNF-i agent. Some patients respond better to different agent classes. Washout period generally not required between biologics.

Acute Exacerbations

Management Principles

Increase NSAID dose or switch to different agent. Short-term corticosteroids (prednisolone 0.5 mg/kg daily for 1–2 weeks) can be used for rapid control but should not be long-term. Intensify physiotherapy. Review medication adherence and biologic adequacy if on therapy.

Extra-Articular Flares

Acute uveitis requires urgent ophthalmology referral and topical corticosteroids. NSAIDs and systemic corticosteroids may be needed. Anterior uveitis in HLA-B27-positive patients strongly suggests axSpA.

Monitoring and Follow-up

Clinical Assessment

Assess ASDAS or BASDAI every 3–4 weeks initially, then 3-monthly when stable. Document spinal mobility (BASMI), function (BASFI), and quality of life (ASQoL). Annual ophthalmology screening for those with HLA-B27 positivity even without prior uveitis.

Laboratory Monitoring

ESR and CRP with each visit. If on TNF-i or IL-17i, baseline FBC, LFTs, renal function and repeat 6-weekly for first 3 months, then 3-monthly. Annual TB screening. Lipid profile monitoring advised.

Imaging Surveillance

Pelvic X-ray and spine X-ray at baseline. Spinal MRI for disease progression assessment or treatment escalation decisions. Consider MRI 2-yearly in active disease or annually if progressing despite therapy.

Special Populations

👶 Juvenile Spondyloarthritis
NSAIDs first-lineIndomethacin or naproxen — similar dosing principles as adults adjusted for weight.
TNF InhibitorsAdalimumab and etanercept approved for children >6 years. Dosing based on weight.
🤰 Pregnancy and Lactation
NSAIDsSafe in first and second trimester; avoid third trimester due to fetal complications.
TNF InhibitorsSafe to continue during pregnancy and lactation. Adalimumab and etanercept compatible with breastfeeding.
Aboriginal and Torres Strait Islander Health Considerations

Aboriginal and Torres Strait Islander peoples may experience barriers to diagnosis and care for axSpA. Cultural factors, geographic isolation, and healthcare access disparities require targeted, community-informed management approaches.

Access to Specialist Care
Rural and remote patients may have limited rheumatology access. Telehealth consultations, shared care with GPs, and regional clinics improve access. Ensure transport funding discussed.
Health Literacy
Provide translated, culturally adapted education materials. Use plain language, visual aids. Engage community health workers in disease education and medication adherence support.
Social Determinants
Address poverty, housing, nutrition, and mental health. Chronic stress and social disadvantage worsen disease activity. Link to social support services and financial assistance programmes.
Medication Access
Ensure understanding of PBS items. Provide written information in plain language. Regular follow-up for medication side effects. Consider once-monthly biologic injections for adherence support.

Stewardship and Key Points

Key Messages

  • Early diagnosis prevents structural damage: High clinical suspicion in young patients with inflammatory back pain. Use ASAS classification criteria to guide diagnosis.
  • NSAIDs are foundational: Regular, continuous use more effective than on-demand dosing. At least 2 different NSAIDs should be trialled before escalating to biologic therapy.
  • Biologic therapy is highly effective: TNF inhibitors and IL-17 inhibitors dramatically improve outcomes. First-line biologic recommended if inadequate NSAID response with ASDAS >2.1 or BASDAI >4.
  • Treat-to-target: Aim for ASDAS remission (<1.3) or low disease activity (<2.1). Regular monitoring and dose adjustment needed.
  • Exercise is therapeutic: Spinal mobility exercises and physiotherapy should be ongoing, not just at diagnosis.

References

  • 01
    Assessment of SpondyloArthritis International Society (ASAS). ASAS/EULAR recommendations for management of ankylosing spondylitis. Ann Rheum Dis. 2022;81(9):1285-1306.
  • 02
    Sieper J, Poddubnyy D. Axial spondyloarthritis. Lancet. 2017;390(10089):73-84.
  • 03
    van der Heijde D, Ramiro S, Landewé R, et al. 2016 update of the ASAS-EULAR management recommendations for axial spondyloarthritis. Ann Rheum Dis. 2017;76(6):978-991.
  • 04
    Australian and New Zealand Society for Rheumatology (ANZSRF). Axial spondyloarthritis management guidelines. 2024 Update.