Overview of incorrectly referred/incorrectly not referred patients with chronic back pain by the referral strategies using classification by the ASAS axSpA criteria as the external standard
| Incorrectly referred/incorrectly not referred patients | ||||||
|---|---|---|---|---|---|---|
| Incorrectly not referred (ie, FN) patients† | ||||||
| Incorrectly referred (ie, FP) patients* | Fulfilling imaging arm | |||||
| Strategy | N | With PTP≥80% axSpA N (% of total FP patients) | N (%) out of 79 | Radiographic sacroiliitis | Sacroiliitis on MRI only | Fulfilling clinical arm only |
| Brandt I | 163 | 8 (5%) | 0 (0%) | – | – | – |
| Brandt II | 138 | 8 (6%) | 2 (3%) | 1 | 1 | – |
| Brandt III | 69 | 7 (10%) | 8 (10%) | 4 | 4 | – |
| Hermann | 130 | 7 (5%) | 12 (15%) | 5 | 3 | 4 |
| MASTER | 46 | 7 (15%) | 19 (24%) | 11 | 7 | 1 |
| Braun IBP | 113 | 8 (7%) | 14 (18%) | 3 | 4 | 7 |
| RADAR | 70 | 7 (10%) | 8 (10%) | 6 | 2 | – |
| RADAR 2/3 | 43 | 4 (9%) | 48 (61%) | 12 | 11 | 25 |
| Braun two-step | 72 | 8 (11%) | 8 (10%) | 3 | 5 | – |
| Braun two-step alt. | 50 | 7 (14%) | 11 (14%) | 4 | 7 | – |
| CaFaSpA ≥1pt | 126 | 7 (6%) | 5 (6%) | 2 | 3 | – |
| CaFaSpA ≥2pt | 47 | 4 (9%) | 31 (39%) | 14 | 10 | 7 |
| ASAS | 152 | 8 (5%) | 0 (0%) | – | – | – |
*FP patients are patients not fulfilling the axSpA criteria who are referred by the strategies.
†FN patients are patients fulfilling the axSpA criteria who are not referred by the strategies.
alt, alternative; ASAS, Assessment in SpondyloArthritis international Society; axSpA, axial spondyloarthritis; IBP, inflammatory back pain; FN, false-negative; FP, false-positive; PTP, post-test probability; RADAR, Recognising and Diagnosing Ankylosing Spondylitis Reliably.