Group | n | Mean (SD) age (years) | Male/female ratio | Disease duration (years) (SD) |
Ankylosing spondylitis (all HLA-B27+) | 25 | 38.7 (12.1) | 16/9 | 10.6 (4.7) |
Healthy HLA-B27 positive controls | 18 | 39.6 (11.4) | 11/7 | — |
Healthy HLA-B27 negative controls | 22 | 41.2 (13.2) | 12/10 | — |