Table 1 The reference standards of continuous and nominal scales as independent variables in multiple logistic regression analyses
Continuous scale | One-unit increase |
Age (years) | Per 1Â year |
Body mass index (kg/m2) | Per 1Â kg/m2 |
Visual analogue scale (mm) | |
 Low back pain | Per 1 mm |
 Lower extremity pain | Per 1 mm |
 Lower extremity numbness | Per 1 mm |
Bone mineral density (g/cm2) | Per 0.1Â g/cm2 |
Range of motion (°) | Per 1° |
Spinopelvic alignment | |
 Thoracic kyphosis (°) | Per 1° |
 Lumbar lordosis (°) | Per 1° |
 Sagittal vertical axis (mm) | Per 10 mm |
 Sacral slope (°) | Per 1° |
 Pelvic tilt (°) | Per 1° |
 Pelvic incidence (°) | Per 1° |
 Pelvic incidence − Lumbar lordosis (°) | Per 1° |
Cross sectional area (mm2) | |
 L3 − L4 | Per 10mm2 |
 L4 − L5 | Per 10mm2 |
 L5 − S1 | Per 10mm2 |
Fat infiltration (%) | |
 L3 − L4 | Per 1% |
 L4 − L5 | Per 1% |
 L5 − S1 | Per 1% |
T2 value (ms) | |
 L3 − L4 | |
 Anterior annulus fibrosus | Per 1 ms |
 Nucleus pulposus | Per 1 ms |
 Posterior annulus fibrosus | Per 1 ms |
 L4 − L5 | |
 Anterior annulus fibrosus | Per 1 ms |
 Nucleus pulposus | Per 1 ms |
 Posterior annulus fibrosus | Per 1 ms |
 L5 − S1 | |
 Anterior annulus fibrosus | Per 1 ms |
 Nucleus pulposus | Per 1 ms |
 Posterior annulus fibrosus | Per 1 ms |
Nominal scale | |
Sex | Â |
 Male |  |
 Female (reference) |  |
Lower extremity symptoms | Â |
 Cauda equina |  |
 Radicular pain |  |
 Mixed |  |
Spondylolisthesis | Â |
 Yes |  |
 No (reference) |  |
Modic change | Â |
 None |  |
 Type 1 |  |
 Type 2 |  |
 Type 3 |  |
Facet joint degeneration | Â |
 L3 − 4 |  |
 Grade0 − 1 |  |
 Grade2 − 3 |  |
 L4 − 5 |  |
 Grade0 − 1 |  |
 Grade2 − 3 |  |
 L5 − S |  |
 Grade0 − 1 |  |
 Grade2 − 3 |  |