The risk of treatment for pain in the distal upper extremities with increasing levels of wrist angular velocity and exertion of force
| Physical exposures | Events | Person-years | IR | IRR, crude (95% CI) | IRR, model 1* (95% CI) | IRR, model 2 (95% CI) |
| Wrist angular velocity | ||||||
| Continuous variable | ||||||
| Men | 698 | 454 800.2 | 15.3 | 1.02 (1.01 to 1.03) | 1.02 (1.00 to 1.03) | 1.02 (1.00 to 1.03) |
| Women | 387 | 161 959.6 | 24.0 | 0.99 (0.97 to 1.00) | 0.98 (0.97 to 0.99) | 0.97 (0.96 to 0.99) |
| Categorical variable† | ||||||
| Low (ref) | ||||||
| Men (3.5–<10.4 o/s) | 212 | 199 898.5 | 10.6 | 1 | 1 | 1 |
| Women (3.5–<10.4 o/s) | 67 | 18 757.3 | 35.7 | 1 | 1 | 1 |
| Medium | ||||||
| Men (10.4–14.3 o/s) | 390 | 187 154.1 | 20.8 | 1.96 (1.66 to 2.32) | 2.08 (1.73 to 2.50) | 1.20 (0.94 to 1.54) |
| Women (10.4–18.3 o/s) | 89 | 44 539.4 | 20.0 | 0.56 (0.41 to 0.77) | 0.82 (0.59 to 1.14) | 0.82 (0.59 to 1.14) |
| High | ||||||
| Men (>14.3 o/s) | 96 | 67 747.8 | 14.2 | 1.34 (1.05 to 1.70) | 1.48 (1.15 to 1.92) | 1.13 (0.86 to 1.49) |
| Women (>18.3 o/s) | 231 | 97 704.0 | 23.6 | 0.66 (0.50 to 0.87) | 0.70 (0.53 to 0.93) | 0.71 (0.53 to 0.93) |
| Wrist force | ||||||
| Continuous variable | ||||||
| Men | 698 | 454 800.2 | 15.3 | 1.48 (1.37 to 1.61) | 1.50 (1.38 to 1.63) | 1.50 (1.38 to 1.63) |
| Women | 387 | 161 959.6 | 24.0 | 0.97 (0.84 to 1.13) | 0.87 (0.74 to 1.02) | 1.13 (0.89 to 1.43) |
| Categorical variable† | ||||||
| Low (ref) | ||||||
| Men (1.0–2.45) | 765 | 190 180.1 | 8.7 | 1 | 1 | 1 |
| Women (1.0–2.15) | 147 | 59 919.1 | 24.5 | 1 | 1 | 1 |
| Medium | ||||||
| Men (>2.45–4.15) | 313 | 162 266.1 | 19.3 | 2.22 (1.84 to 2.68) | 2.23 (1.83 to 2.72) | 1.99 (1.55 to 2.56) |
| Women (>2.15–2.55) | 231 | 97 704.0 | 23.6 | 0.96 (0.78 to 1.19) | 0.79 (0.63 to 0.99) | 0.71 (0.53 to 0.94) |
| High | ||||||
| Men (>4.15) | 220 | 102 354.0 | 21.5 | 2.48 (2.02 to 3.03) | 2.65 (2.13 to 3.29) | 2.31 (1.72 to 3.09) |
| Women (>2.55) | 9 | 3377.6 | 26.6 | 1.09 (0.55 to 2.13) | 1.07 (0.54 to 2.10) | 1.06 (0.54 to 2.08) |
Estimates in bold significant at p<0.05. Model 1: adjusted for age and calendar-year, diagnoses of rheumatoid arthritis and fractures of the wrist, elbow or arm. Model 2: adjusted for model 1 and the other exposure, that is, force or repetition.
*No cases of incident treatment among women with rheumatoid arthritis. This variable was left out in the analyses for women.
†Tertiles of exposure were defined for sexes separately.
IR, incidence rate per 10 000 person-years; IRR, incidence rate ratio.