Are there differences in HLA-B27 prevalence between axSpA and pSpA, and how does this affect classification?

HLA-B27 is a major genetic marker for SpA, but its prevalence differs significantly between axial and peripheral subtypes, influencing both diagnosis and classification (Table 1).

Table 1. Differences in HLA-B27 prevalence and clinical impact between axSpA and pSpA

 

Feature

axSpA

pSpA

HLA-B27

prevalence

Found in approximately 74–92% of patients with r-axSpA and nr-axSpA.

Lower prevalence, varies by subtype: PsA: ~50% Reactive and IBD-related arthritis: 60–80%

Clinical influence

Associated with earlier onset. More common in males. Linked to sacroiliitis and uveitis.

More heterogeneous presentation.

HLA-B27 status is less critical for diagnosis.

Role in classification

Central to ASAS criteria. Especially valuable in nr-axSpA.

Supportive but not essential. Greater emphasis on clinical and extra-articular features.

REFERENCE

  1. Zhang S, Wang Y, Peng L, Su J, Zeng X, Li M, Wu Z, Xu J, Yang M, Wu L, Zhao C, Duan X, Li Q, Zhu J, Fan W. Comparison of Clinical Features in HLA-B27 Positive and Negative Patients With Axial Spondyloarthritis: Results From a Cohort of 4,131 Patients. Front Med (Lausanne). 2020 Dec 23;7:609562.
  2. Londono, J., Pacheco-Tena, C., Santos, A.M. et al. Differences between radiographic and non- radiographic axial spondyloarthritis patients in a Mexican Sci Rep 14, 10342 (2024).
  3. Schwartzman S, Ruderman EM. A Road Map of the Axial Spondyloarthritis Continuum. Mayo Clinic 2022 Jan 1;97(1):134–45.

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