Table 3.
Number of persons with carpal tunnel syndrome (CTS) (diagnosis or surgery), incidence rate (IR), crude and adjusted incidence rate ratio (IRR) of CTS cases by 1-year exposure levels (intensity*duration) shown for wrist angular velocity, mean power frequency and range of motion
| Exposure variable | ||||||
| Angular velocity, °/s | 0−<20th percentile 0.01≤−<6.09 |
20th≤−40th percentile 6.09≤−7.28 |
40th≤−60th percentile 7.28≤−11.1 |
60th≤−80th percentile 11.1≤−14.5 |
80th≤−≤100th percentile 14.5≤−≤37.6 |
Total |
| CTS, number of cases | 472 | 1408 | 1265 | 1748 | 1941 | 6834 |
| Person-years | 686 215 | 1 460 532 | 983 846 | 1 118 501 | 1 127 833 | 5 376 927 |
| IR* | 6.9 | 9.6 | 12.9 | 15.6 | 17.2 | 12.7 |
| IRR, crude | 1.00 (ref.) | 1.40 (1.26 to 1.56) | 1.87 (1.68 to 2.08) | 2.27 (2.05 to 2.52) | 2.50 (2.26 to 2.77) | |
| IRR, adjusted† | 1.00 (ref.) | 1.04 (0.93 to 1.16) | 1.58 (1.42 to 1.76) | 2.02 (1.82 to 2.24) | 2.31 (2.09 to 2.56) | |
| Mean power frequency, Hz | 0−<20th percentile <0.001≤−<0.23 |
20th≤−40th percentile 0.23≤−0.24 |
40th≤−60th percentile 0.24≤−0.27 |
60th≤−80th percentile 0.27≤−0.29 |
80th≤−≤100th percentile 0.29≤−0.45 |
Total |
| CTS, number of cases | 897 | 1117 | 1068 | 1941 | 1811 | 6834 |
| Person years | 936 938 | 1 179 089 | 924 313 | 1 258 279 | 1 078 308 | 5 376 927 |
| IR* | 9.6 | 9.5 | 11.6 | 15.4 | 16.8 | 12.7 |
| IRR, crude | 1.00 (ref.) | 0.99 (0.91 to 1.08) | 1.21 (1.10 to 1.32) | 1.61 (1.49 to 1.74) | 1.75 (1.62 to 1.90) | |
| IRR, adjusted† | 1.00 (ref.) | 0.78 (0.72 to 0.86) | 1.51 (1.37 to 1.66) | 1.33 (1.23 to 1.44) | 1.83 (1.68 to 1.98) |
| Range of motion, ° | 0−<20th percentile 0.05≤−<48.7 |
20th≤−40th percentile 48.7≤−49.6 |
40th≤−60th percentile 49.6≤−52.8 |
60th≤−80th percentile 52.8≤−59.6 |
80th≤−≤100th percentile 59.6≤−65.1 |
Total |
| CTS, number of cases | 974 | 1196 | 1229 | 1711 | 1724 | 6834 |
| Person years | 881 074 | 1 241 358 | 1 073 460 | 963 779 | 1 217 256 | 5 376 927 |
| IR* | 11.1 | 9.6 | 11.5 | 17.8 | 14.2 | 12.7 |
| IRR, crude | 1.00 (ref.) | 0.87 (0.80 to 0.95) | 1.04 (0.95 to 1.13) | 1.61 (1.48 to 1.74) | 1.28 (1.18 to 1.39) | |
| IRR, adjusted† | 1.00 (ref.) | 0.62 (0.57 to 0.68) | 1.33 (1.21 to 1.45) | 1.44 (1.33 to 1.55) | 0.97 (0.90 to 1.06) |
Numbers in brackets are 95% CI. Persons with unknown exposures are not included in the lowest exposure category.
*Number of cases pr. 10 000 person-years.
†Adjusted for sex, age, calendar year, pregnancy, wrist-near fracture, hypothyroidism, rheumatoid arthritis, diabetes mellitus and obesity.
IR, incidence rate.