Distribution of the study population according to T-OPLL (+) or (−)
| T-OPLL (+) | T-OPLL (−) | All | |
| Sex | N | N | N |
| Male | 14 | 1778 | 1792 |
| Female | 36 | 1471 | 1507 |
| Age, mean | 64.6 | 57.5 | 57.6 |
| Age group, years | N (%)* | N | |
| <10 | 0 | 7 | 7 |
| 10–19 | 0 | 31 | 31 |
| 20–29 | 1 (0.5) | 219 | 220 |
| 30–39 | 1 (0.3) | 318 | 319 |
| 40–49 | 5 (1.5) | 332 | 337 |
| 50–59 | 10 (1.4) | 705 | 715 |
| 60–69 | 8 (1.0) | 832 | 840 |
| 70–79 | 21 (3.8) | 528 | 549 |
| 80–89 | 4 (1.8) | 224 | 228 |
| 90–99 | 0 | 51 | 51 |
| >100 | 0 | 2 | 2 |
| Total (%) | 50 (1.5) | 3249 | 3299 |
* T OPLL (+) percentage per age group.
T-OPLL, thoracic ossification of the posterior longitudinal ligament.