Radiographic sacroiliitis according to the modified New York criteria at baseline and at follow-up (on average 4.4 years)
| Follow-up radiograph | Total | ||
|---|---|---|---|
| Baseline radiograph | Positive | Negative | |
| Positive | 26 | 36 | 62 |
| Negative | 54 | 241 | 295 |
| Total | 80 | 277 | 357 |
| PPV (%) | 41.9 | ||
| NPV (%) | 81.7 | ||
PPV, positive predictive value; NPV, negative predictive value.