Sensitivity and specificity of single IBP parameters as assessed by the diagnosing rheumatologist, the blinded rheumatologist and patient for the diagnosis of axSpA
| IBP parameter | Blinded rheumatologist | Diagnosing rheumatologist | Patient | ||||||
| Sensitivity, % (95% CI) | Specificity, % (95% CI) | LR+ | Sensitivity, % (95% CI) | Specificity, % (95% CI) | LR+ | Sensitivity, % (95% CI) | Specificity, % (95% CI) | LR+ | |
| Insidious onset | 75.6 (69.3 to 81.8) | 24.4 (18.8 to 30.1) | 1.0 | 83.9 (78.5 to 89.3) | 19.6 (14.4 to 24.7) | 1.0 | 76.2 (69.8 to 82.5) | 15.3 (10.5 to 20.1) | 0.9 |
| Morning stiffness ≥30 min | 71.1 (63.8 to 78.3) | 33.9 (27.0 to 40.8) | 1.1 | 67.4 (59.8 to 74.9) | 37.7 (30.4 to 45.1) | 1.1 | 69.4 (62.5 to 76.3) | 30.1 (24.0 to 36.2) | 1.0 |
| Improvement with exercise | 88.9 (84.3 to 93.5) | 22.7 (17.2 to 28.1) | 1.2 | 85.6 (80.4 to 90.7) | 30.7 (24.6 to 36.7) | 1.2 | 83.0 (77.4 to 88.7) | 18.6 (13.4 to 23.8) | 1.0 |
| No improvement with rest | 73.9 (67.5 to 80.3) | 44.9 (38.4 to 51.4) | 1.3 | 81.6 (75.9 to 87.2) | 41.8 (35.3 to 48.2) | 1.4 | 81.1 (75.1 to 87.1) | 30.8 (24.5 to 37.0) | 1.2 |
| Pain at night | 74.4 (68.1 to 80.8) | 33.8 (27.6 to 40.0) | 1.1 | 82.8 (77.3 to 88.3) | 30.1 (24.8 to 36.9) | 1.2 | 77.6 (71.4 to 83.8) | 26.9 (21.1 to 32.8) | 1.1 |
| Alternating buttock pain | 60.0 (52.8 to 67.2) | 58.2 (51.8 to 64.7) | 1.4 | 57.8 (50.6 to 65.0) | 63.4 (57.0 to 69.7) | 1.6 | 68.2 (61.3 to 75.1) | 43.4 (36.8 to 50.0) | 1.2 |
IBP, inflammatory back pain; LR, likelihood ratio; SpA, spondyloarthritis; axSpA, axial spondyloarthritis.