Table 2.
Neck Disability Index (NDI) scores
| NDI score | Exposed group | Control group | P value* |
|---|---|---|---|
| (N=99) | (N=931) | ||
| Median (min–max) | Median (min–max) | ||
| Mean (SD) | Mean (SD) | ||
| Items (0–5) | |||
| Pain intensity | 1 (0–5) | 0 (0–5) | <0.001 |
| 1.3 (1.3) | 0.5 (0.9) | - | |
| Personal care | 0 (0–5) | 0 (0–4) | - |
| 0.5 (0.9) | 0.1 (0.5) | - | |
| Lifting | 1 (0–5) | 0 (0–5) | <0.001 |
| 1.5 (1.6) | 0.6 (1.2) | - | |
| Reading | 0 (0–5) | 0 (0–5) | - |
| 1.1 (1.3) | 0.4 (0.9) | - | |
| Headache | 1 (0–5) | 0 (0–5) | <0.001 |
| 1.5 (1.6) | 1.0 (1.3) | - | |
| Concentration | 0 (0–5) | 0 (0–5) | - |
| 0.8 (1.2) | 0.4 (0.8) | - | |
| Work | 1 (0–5) | 0 (0–5) | <0.001 |
| 1.2 (1.5) | 0.7 (1.1) | - | |
| Driving | 0 (0–5) | 0 (0–5) | - |
| 0.9 (1.3) | 0.4 (0.9) | - | |
| Sleep | 1 (0–5) | 0 (0–5) | <0.001 |
| 1.2 (1.5) | 0.7 (1.1) | ||
| Recreation | 0 (0–5) | 0 (0–5) | |
| 1.0 (1.4) | 0.5 (1.1) | ||
| Median (for all 10 items) | 1 (0–5) | 0 (0–5) | <0.001 |
| 1.0 (1.2) | 0.4 (0.8) | ||
| Total score (0–100) | 18 (0–80) | 4 (0–98) | <0.001 |
| 22.1 (21.7) | 10.6 (15.2) | ||