Comparison of the patients according to the activity and chronicity of sacroiliitis
| MRI grading | Classified as group | Number | Disease duration (y) (mean (SD)) | Inflammatory cells/10 mm2 (mean (SD)) | p Value |
| Activity | |||||
| enhancement 30–70% | A | 8 | 5.6 (3.3) | 6.0 (5.6) | NS |
| enhancement >70% | B | 12 | 4.7 (5.8) | 21.8 (17.3) | 0.053-150 |
| Chronicity | |||||
| chronic changes ⩽ grade II | I | 9 | 2.5 (2.9)† | 26.7 (20.1) | 0.043-150 |
| chronic changes > grade II | II | 13 | 7.3 (4.8)† | 5.3 (5.2) | NS |
↵3-150 For the comparison of relative proportions of inflammatory cells. †The difference in disease duration between grade 1 and grade 2 was significant (p=0.02).