Table 4

Sensitivity and specificity of the main entry criteria and other SpA-specific items for AS and axial SpA in primary care

CriteriaSensitivity for axial SpA (AS) %Specificity for axial SpA (AS) %Positive likelihood ratioNegative likelihood ratio
Morning stiffness >30 min35.4 (46.8)66.5 (68.0)1.11.0
Improvement by movement not by rest77.9 (83.0)39.7 (36.4)1.30.6
Waking up in the second half of the night because of back pain58.4 (70.2)57.5 (59.8)1.70.7
Improvement by NSAIDs within 48 h93.8 (78.7)48.0 (48.3)1.80.1
Alternating buttock pain24.8 (34.0)88.5 (88.5)2.20.9
History of enthesitis15.091.91.90.9
History of arthritis10.695.72.50.9
Age <35 years77.043.51.40.5
HLA B27 (as determined in primary care)35.490.93.90.7
≥3 criteria85.149.81.70.3
  • AS, ankylosing spondylitis; NSAID, non-steroidal anti-inflammatory drug; SpA, spondyloarthritis.