GPAtlas🧭 When to suspect
Spondyloarthritis (SpA) is a family of chronic inflammatory conditions that share a genetic and clinical overlap. It is usefully split into axial disease – ankylosing spondylitis (radiographic axial SpA) and non-radiographic axial SpA (nr-axSpA) – and peripheral disease – psoriatic arthritis (PsA), reactive arthritis, and enteropathic arthritis (associated with inflammatory bowel disease). Many patients have a mix of both, alongside extra-articular links such as uveitis, psoriasis and inflammatory bowel disease (IBD).
The recognition challenge is real: axial SpA is repeatedly mislabelled as “mechanical” back pain and peripheral disease as unrelated joint problems, so the average delay to diagnosis in the UK is around 8 to 9 years – time in which avoidable structural damage accrues. The condition is not rare (roughly 1 in 200 UK adults) and, importantly, affects women as often as men. The core primary care skill is to spot inflammatory back pain and the peripheral / extra-articular cluster, and to refer.
The single most useful distinction is inflammatory versus mechanical back pain:
| Feature | Inflammatory (suspect SpA) | Mechanical (less concerning) |
|---|---|---|
| Onset | Insidious, before age 45 | Often acute, any age, after activity or injury |
| Duration | > 3 months (chronic) | Frequently self-limiting |
| Morning stiffness | > 30 minutes | Brief, usually minutes |
| Effect of rest | Worse with rest / inactivity | Relieved by rest |
| Effect of movement | Improves with exercise | Worse with activity |
| Night pain | Wakes in the second half of the night | Less typical |
| NSAID response | Often marked, within 48 hours | Variable |
For axial SpA, refer to rheumatology if low back pain started before age 45 and has lasted longer than 3 months, with 4 or more of the following nine criteria; if exactly 3 are present, perform an HLA-B27 (human leukocyte antigen B27) test and refer if positive:
• Low back pain that started before age 35
• Waking in the second half of the night because of symptoms
• Buttock pain
• Improvement with movement
• Improvement within 48 hours of taking a non-steroidal anti-inflammatory drug (NSAID)
• A first-degree relative with spondyloarthritis
• Current or past arthritis
• Current or past enthesitis (inflammation where tendon or ligament meets bone)
• Current or past psoriasis
For peripheral SpA, suspect the diagnosis with new-onset inflammatory arthritis, dactylitis (diffuse “sausage” swelling of a whole digit), unexplained enthesitis (classically heel pain), or peripheral joint symptoms in someone with psoriasis, IBD, uveitis, or a recent gastrointestinal or genitourinary infection.
Source: NICE NG65
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