Seronegative Spondyloarthritides: Statement Analysis
Statements d) and e) are correct: reactive arthritis following extra-articular infection is included among seronegative spondyloarthritides, and HLA-B27 presence is strongly associated with ankylosing spondylitis.
Statement-by-Statement Analysis
a) Psoriatic arthritis is not included among them - FALSE
Psoriatic arthritis is definitively included in the seronegative spondyloarthritides 1. The guidelines explicitly list psoriasis as an extra-articular manifestation and diagnostic criterion for spondyloarthritis, and multiple sources confirm that the SpA family includes ankylosing spondylitis, psoriatic arthritis, reactive arthritis, enteropathic arthritis, and undifferentiated SpA 2, 3, 4, 5.
b) HLA-B27 is always negative in reactive arthritis - FALSE
This statement is categorically incorrect. The guidelines emphasize that spondyloarthritis should not be ruled out based only on negative HLA-B27 results 1. HLA-B27 can be positive in reactive arthritis patients—the term "seronegative" refers to the absence of rheumatoid factor, not HLA-B27 3, 5. While HLA-B27 positivity varies among SpA subtypes, it is not "always negative" in any form of spondyloarthritis.
c) Enthesitis is characteristic and resistant to treatment - FALSE
While enthesitis is indeed a characteristic musculoskeletal manifestation of spondyloarthritides 1, the claim that it is "resistant to treatment" is incorrect. The guidelines provide clear treatment pathways: NSAIDs as first-line therapy, followed by biologics (particularly TNF inhibitors) for persistent disease 1. The evidence does not support that enthesitis is inherently treatment-resistant—rather, it requires appropriate therapeutic escalation when initial treatments fail.
d) They include reactive arthritis following an extra-articular infection - TRUE
This statement is correct. The guidelines explicitly identify "recent genitourinary infection" as a risk factor for spondyloarthritis 1. Reactive arthritis is consistently listed as part of the SpA family, and its association with preceding gastrointestinal or genitourinary infections is well-established 2, 4. The guidelines note that infective antibody testing should not be routinely performed to confirm reactive arthritis in persons who have had gastrointestinal infection, acknowledging the established link 1.
e) The presence of HLA-B27 is strongly associated with ankylosing spondylitis - TRUE
This statement is definitively correct. Multiple sources confirm the strong association between HLA-B27 and ankylosing spondylitis 6, 7. The guidelines note that HLA-B27 positivity increases the likelihood of spondyloarthritis and is used as a diagnostic criterion—patients with only three clinical criteria should still be referred if HLA-B27 is positive 1. Research confirms that HLA-B27 positive individuals have significantly higher risk for disease development, particularly in ankylosing spondylitis 7.
Key Clinical Pitfalls
Do not exclude spondyloarthritis based on negative HLA-B27 alone 1. The disease can occur in HLA-B27 negative patients, and diagnosis requires clinical assessment combined with laboratory and imaging findings.
"Seronegative" refers to rheumatoid factor negativity, not HLA-B27 negativity 3, 5. This terminology confusion leads to misunderstanding about the role of HLA-B27 testing.
Psoriatic arthritis is a core member of the SpA family, not excluded from it 1, 2.