Representative values of sensitivity and specificity for several tests relevant for axial spondyloarthritis as evaluated previously,1,3 along with the resulting LR+ and LR−*
| Parameter | Sensitivity (%) | Specificity (%) | LR+ | LR− |
|---|---|---|---|---|
| CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; HLA, human leucocyte antigen; IBD, inflammatory bowel disease; LR+, positive likelihood ratio; LR−, negative likelihood ratio; NSAID, non-steroidal anti-inflammatory drugs; SpA, spondyloarthritis. | ||||
| *LR+ = sensitivity/(1 – specificity); LR− = (1 – sensitivity)/specificity. | ||||
| †As enthesitis, dactylitis, uveitis, peripheral arthritis, psoriasis and IBD may not be present at disease onset but may develop later, it is recommended to ignore a negative test result of these tests in an early state of possible axial SpA. The LR− of parameters, which should be ignored, are shown in brackets. | ||||
| ‡The figures for sensitivity and specificity of HLA-B27 refer to a European Caucasian population. In European Caucasian patients with psoriasis or IBD, a sensitivity of 50%, a specificity of 90%, an LR+ of 5.0 and an LR− of 0.56 for HLA-B27 should be applied. In other ethnic populations, sensitivity and specificity of HLA-B27 may be different, resulting in different LR+ and LR− (also discussed by Rudwaleit et al1). | ||||
| Inflammatory type of back pain5,6 | 75 | 76 | 3.1 | 0.33 |
| Heel pain (enthesitis) | 37 | 89 | 3.4 | (0.71)† |
| Peripheral arthritis | 40 | 90 | 4.0 | (0.67)† |
| Dactylitis | 18 | 96 | 4.5 | (0.85)† |
| Iritis or anterior uveitis | 22 | 97 | 7.3 | (0.80)† |
| Psoriasis | 10 | 96 | 2.5 | (0.94)† |
| IBD | 4 | 99 | 4.0 | (0.97)† |
| Positive family history for axial SpA, reactive arthritis, psoriasis, IBD or anterior uveitis | 32 | 95 | 6.4 | 0.72 |
| Good response to NSAIDs | 77 | 85 | 5.1 | 0.27 |
| Raised acute-phase reactants (CRP/ESR) | 50 | 80 | 2.5 | 0.63 |
| HLA-B27‡ | 90 | 90 | 9.0 | 0.11 |
| Sacroiliitis shown by magnetic resonance imaging | 90 | 90 | 9.0 | 0.11 |