The performance of the ASAS recommendations in a primary care CLBP population (N=941) calculated per number of SpA parameters present in a patient
| Number of parameters present* | Sensitivity (%) | Specificity (%) | PPV (%) |
|---|---|---|---|
| ≥1 | 100.0 | 18.6 | 22.6 |
| ≥2 | 100.0 | 60.1 | 37.6 |
| ≥3 | 66.9 | 86.5 | 54.0 |
| ≥4 | 30.4 | 96.5 | 67.0 |
| ≥5 | 9.4 | 98.8 | 65.4 |
| ≥6 | 2.8 | 99.6 | 62.5 |
*Parameters as described by the ASAS recommendations; inflammatory back pain; HLA-B27 positivity; sacroiliitis on imaging (X-ray or MRI); peripheral manifestations (arthritis, enthesitis, dactylitis); extra-articular manifestation (psoriasis, inflammatory bowel disease, uveitis); positive family history for SpA; good response to non-steroidal anti-inflammatory drugs; elevated acute phase reactants (ESR or CRP).
ASAS, Assessment of SpondyloArthritis international Society; CLBP, chronic low back pain; CRP, C reactive protein; ESR, erythrocyte sedimentation rate; SpA, spondyloarthritis; PPV, positive predictive value.