Reviewed on : 9 Nov 2022

Reviewed by : Dr Tim Blake Consultant Rheumatologist UHCW

Expires : 9 Nov 2024

Back Pain: Suspected Ankylosing Spondylitis / Spondyloarthritis

What is Ankylosing Spondylitis (AS) and Spondyloarthritis (SpA)?

Ankylosing Spondylitis (AS) is a rheumatic disease that causes arthritis of the spine and sacroiliac joints.

The term ‘Ankylosing’ means fusing together, while Spondylitis refers to the inflammation of vertebrae.

AS is typically a painful, progressive rheumatic disease. It primarily affects the spine, but can also affect other joints, tendons, and ligaments. Sometimes, other areas like the eyes, lungs, bowel, and heart can also become affected. AS is the prototype of Spondyloarthritis (SpA).

There are two main types, which can also co-exist:

• Axial Spondyloarthritis – involving SIJs/spine/costovertebral joint region
• Peripheral Spondyloarthritis – including dactylitis (whole digit inflammation and swelling), enthesitis, peripheral joint inflammation and tendonitis

Key points about Spondyloarthritis:

• If persisting back, tendon or joint pain – ask about psoriasis, inflammatory bowel disease, uveitis
• AxSpA affects women and men equally
• Inflammatory markers (ESR & CRP) can be normal
• Do not exclude possibility of SpA if HLA B27 –ve
• MRI for AxSpA differs from lumbar MRI protocol

Why is it important to screen for Spondyloarthritis?

• Average time to be diagnosed for many people is 8-9 years
• Spondyloarthritis is often mistaken as chronic back pain, or as unrelated tendonitis and joint problems
• Symptoms can move between areas, be asymmetrical, and can flare and settle
• This guidance links with NICE Guidance on Low Back Pain and Sciatica (2016) to ensure inflammatory back symptoms are not mistaken as chronic mechanical LBP

Diagnostic Tools
The diagnosis of Ankylosing Spondylitis is based on evaluating the patient’s symptoms, a physical examination, X-ray and MRI findings, and blood tests.

A physical examination might reveal limited spinal motion, chest expansion, or characteristic tender points termed enthesitis.

The condition can affect all age groups including children; however, the most common age group includes those in late teens or early adulthood (< 45 years).

The typical symptoms of AS include:

• Slow or gradual onset of back pain and stiffness
• Limited expansion of the chest
• Hip pain and stiffness
• Early morning stiffness and pain
• Persistent pain for more than three months
• Relief from pain after exercise and recurrence after rest.

Additional features:

• Heel pain (enthesitis)
• Dactylitis
• Uveitis
• Positive family history for SpA
• Inflammatory bowel disease
• Alternating buttock pain
• Psoriasis
• Asymmetrical arthritis
• Positive response to nonsteroidal anti-inflammatory drugs (NSAIDs)
• Elevated acute phase reactants (ESR or CRP).

The following tests should be carried out:

• Blood tests, which may show mild anaemia, or elevated ESR/CRP
• HLA-B27 antigen test (present in up to 95% of Caucasian patients with AS, but also in 8% of general Caucasian population)
• AP plain X-ray of the pelvis to include the sacroiliac joints (SIJs)

Referral if suspect Axial Spondyloarthritis (see Referral Form link right)

Consider referral to rheumatology if a person presents with Back pain > 3 mths with onset before 45 years of age and if 4 or more additional features below:

• Onset before 35 years of age (increases suspicion)
• Woken second half of night by symptoms
• Improves with movement
• Buttock pain
• Improves with NSAIDs (often within 48 hours)
• Close relative (parent, brother, sister, son or daughter) with spondyloarthritis
• Current or past psoriasis, or family history of psoriasis
• Other type of arthritis, enthesitis, or pain or swelling in tendon or joints not due to injury

If only 3 additional features, NICE recommends testing for HLA B27 – if positive – refer

Uveitis: ask people with back pain > 3months with onset before 45yrs if history of uveitis, and if HLA B27 positive or has a history of psoriasis – refer

SPADE Tool: Please tick all that apply – See www.spadetool.co.uk for online calculation

Please complete SPADE tool (see below) to assist with triage and prioritisation, and refer to Rheumatology AxSpA (AS) clinic. The SPADE tool has been designed to assist medical professionals define the probability of axial spondyloarthritis in a patient with chronic back pain, below the age of 45 with no definitive changes on X-ray

Inflammatory type of back pain

Heel pain (enthesitis)

Peripheral arthritis

Dactylitis

Iritis or anterior uveitis

Psoriasis

IBD (Crohn’s disease or ulcerative colitis)

Positive family history of axial SpA, reactive arthritis, psoriasis, IBD or anterior uveitis

Good response to NSAIDs

Raised acute-phase reactants (CRP/ESR)

HLAB27

Sacroiliitis shown by MRI

Referrals can be made to Rheumatology or directly to Dr Blake. If a patient has clear joint swelling, they should be referred to the Early Arthritis Clinic to avoid delay

The following tests should be carried out:

• Blood tests, which may show mild anaemia, or elevated ESR/CRP
• HLA-B27 antigen test (present in up to 95% of Caucasian patients with AS, but also in 8% of general Caucasian population)
• AP plain X-ray of the pelvis to include the sacroiliac joints (SIJs)
• Referral if suspect Peripheral Spondyloarthritis

Refer to rheumatology if a person presents with:

• Dactylitis (whole swollen digit- ‘sausage’ finger or toe) or
• Persistent or multiple-site enthesitis without apparent mechanical cause and with other features, including:
• Back pain without apparent mechanical cause
• Current/past psoriasis
• Inflammatory bowel disease (Crohn’s disease/ ulcerative colitis) or uveitis
• Close relative (parent, brother, sister, son or daughter) with SpA or psoriasis
• Symptom onset following GIT or genitourinary infection

Further resources

National Axial Spondyloarthritis Society: https://nass.co.uk/

AStretch: www.astretch.co.uk

RCGP -free eLearning module: http://elearning.rcgp.org.uk/course/info.php?id=229