Comparison of US enthesis abnormalities according to the presence of an MRI sacro-iliitis according to the ASAS definition
| Patients with sacro-iliitis, n=134 | Patients without sacro-iliitis, n=262 | p Value | |
| US structural score, med (IQR) | 1 (0–2) | 0 (0–1) | 0.2 |
| US PD score, med (IQR) | 0 (0–0) | 0 (0–0) | 0.4 |
| Number (%) of patients with at least one enthesis abnormal thickness | 33/123 (26.8) | 58/247 (23.5) | 0.5 |
| Number (%) of patients with at least one enthesis bone erosion | 21/126 (16.7) | 38/250 (15.2) | 0.7 |
| Number (%) of patients with at least one enthesis calcification | 31/126 (24.6) | 61/250 (24.4) | 0.9 |
| Number (%) of patients with at least one enthesophyte | 32 (25.4) | 67 (26.7) | 0.8 |
| Number (%) of patients with at least one enthesis abnormal PD signal | 21/126 (16.7) | 35/251 (13.9) | 0.5 |
| Number (%) of patients with at least one Achilles bursitis | 16/134 (11.9) | 25/262 (9.5) | 0.5 |
US structural score, sum of all the entheses with calcification, bone erosions, abnormal thickness, bursitis, enthesophytes; US PD score, sum of all the enthesis with an abnormal power Doppler signal; US, ultrasound.