Table 1.
Demographic characteristics of all study subjects
| Characteristics | Discovery cohort | Validation cohort | ||
|---|---|---|---|---|
| Cases group (n = 300) | Control group (n = 180) | Cases group (n = 620) | Controls group (n = 683) | |
| Gender, n | ||||
| Male | 231 (77) | 135 (75) | 440 (71) | 532 (78) |
| Female | 69 (23) | 45 (25) | 180 (29) | 150 (22) |
| Age (years), (%) mean ± SD | 29.2 ± 9.9 | 24.7 ± 6.7 | 23.2 ± 8.9 | 27.3 ± 9.3 |
| Onset type, n (%) | ||||
| Juvenile onset | 120 (40) | – | 130 (21) | – |
| Adult onset | 180 (60) | – | 490 (79) | – |
| B-27, n (%) | ||||
| Negative | 24 (8) | – | 56 (9) | – |
| Positive | 276 (92) | – | 564 (91) | – |
| Kyphosis, n (%) | ||||
| Negative | 174 (58) | – | 508 (82) | – |
| Positive | 126 (42) | – | 112 (18) | – |
| Bamboo spine, n (%) | ||||
| Negative | 201 (67) | – | 428 (69) | – |
| Positive | 99 (33) | – | 192 (31) | – |
| Radiographic grading of sacroiliitis, n (%) | ||||
| 2/3 | 126 (42) | – | 366 (59) | – |
| 4 | 174 (58) | – | 254 (41) | – |
SD: Standard deviation; –: Not applicable.