Crude and adjusted hazard rate ratios for carpal tunnel syndrome and individual time-weighted average biomechanical exposures
| Crude | Adjusted | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Cutoffs | Cohort (N) | Cases (n) | HR | 95% CI | Cohort (N) | Cases (n) | HR | 95%CI | |
| Force measures | |||||||||
| Peak hand force: worker rated* | 2233 | 157 | 1955 | 142 | |||||
| Lower tertile | ≤2.1 | 38 | 1.00 | 33 | 1.00 | ||||
| Middle tertile | >2.1 & ≤4 | 62 | 1.22 | 0.81 to 1.84 | 57 | 1.70 | 1.08 to 2.68 | ||
| Upper tertile | >4 | 57 | 1.62 | 1.07 to 2.44 | 52 | 2.08 | 1.31 to 3.29 | ||
| Peak hand force: analyst rated* | 2410 | 176 | 2038 | 153 | |||||
| Lower tertile | ≤2.5 | 58 | 1.00 | 49 | 1.00 | ||||
| Middle tertile | >2.5 & ≤4 | 75 | 1.16 | 0.82 to 1.64 | 65 | 1.59 | 1.09 to 2.34 | ||
| Upper tertile | >4 | 43 | 1.65 | 1.11 to 2.46 | 39 | 2.17 | 1.38 to 3.43 | ||
| Repetition measures | |||||||||
| HAL scale: analyst rated† | 2425 | 177 | 2299 | 164 | |||||
| Lower tertile | ≤4 | 66 | 1.00 | 59 | 1.00 | ||||
| Middle tertile | >4 & ≤5.3 | 50 | 1.36 | 0.94 to 1.95 | 48 | 1.54 | 1.02 to 2.32 | ||
| Upper tertile | >5.3 | 61 | 1.21 | 0.85 to 1.73 | 57 | 1.32 | 0.87 to 2.02 | ||
| Total hand repetition rate: video analysis† | 2107 | 159 | 2038 | 153 | |||||
| Lower tertile | ≤13 | 61 | 1.00 | 57 | 1.00 | ||||
| Middle tertile | >13 & ≤26 | 57 | 0.94 | 0.66 to 1.35 | 56 | 1.12 | 0.76 to 1.65 | ||
| Upper tertile | >26 | 41 | 0.77 | 0.52 to 1.15 | 40 | 0.94 | 0.59 to 1.5 | ||
| Forceful hand repetition rate: video analysis‡ | 2384 | 170 | 2354 | 166 | |||||
| Lower tertile | ≤2.6 | 60 | 1.00 | 59 | 1.00 | ||||
| Middle tertile | >2.6 & ≤9.6 | 60 | 1.16 | 0.81 to 1.66 | 57 | 1.53 | 1.05 to 2.25 | ||
| Upper tertile | >9.6 | 50 | 1.26 | 0.87 to 1.84 | 50 | 1.84 | 1.19 to 2.86 | ||
| Duty cycle | |||||||||
| % duration all hand exertions: video analysis† | 2107 | 159 | 2038 | 153 | |||||
| Lower tertile | ≤59% | 45 | 1.00 | 42 | 1.00 | ||||
| Middle tertile | >59% & ≤76% | 57 | 1.20 | 0.81 to 1.77 | 56 | 1.12 | 0.75 to 1.67 | ||
| Upper tertile | >76% | 57 | 1.29 | 0.87 to 1.91 | 55 | 1.13 | 0.75 to 1.68 | ||
| % duration forceful hand exertions: video analysis‡ | 2384 | 170 | 2354 | 166 | |||||
| Lower tertile | ≤11% | 57 | 1.00 | 56 | 1.00 | ||||
| Middle tertile | >11% & ≤32% | 55 | 1.12 | 0.78 to 1.62 | 53 | 1.46 | 0.98 to 2.17 | ||
| Upper tertile | >32% | 58 | 1.48 | 1.03 to 2.13 | 57 | 2.05 | 1.34 to 3.15 | ||
| Posture measures | |||||||||
| % time ≥30°wrist extension: video analysis§ | 2373 | 168 | 2038 | 153 | |||||
| Lower half | ≤5% | 96 | 1.00 | 88 | 1.00 | ||||
| Upper half | >5% | 72 | 0.90 | 0.66 to 1.23 | 65 | 0.87 | 0.59 to 1.29 | ||
| % time ≥30°wrist flexion: video analysis§ | 2374 | 168 | 2038 | 153 | |||||
| Lower half | ≤1% | 86 | 1.00 | 83 | 1.00 | ||||
| Upper half | >1% | 82 | 0.94 | 0.69 to 1.27 | 70 | 0.83 | 0.60 to 1.15 | ||
| Other | |||||||||
| Vibration: analyst rated¶ | 2092 | 162 | 1719 | 139 | |||||
| Lower half | 0 | 96 | 1.00 | 82 | 1.00 | ||||
| Upper half | >0 | 66 | 1.07 | 0.78 to 1.47 | 57 | 1.04 | 0.69 to 1.55 | ||
All models include age, gender, body mass index, study site.
*Adjusted for total repetition rate, % duration all exertions, % time ≥30° wrist flexion.
†Adjusted for peak force, % time ≥30° wrist flexion.
‡Adjusted for % time ≥30° wrist flexion.
§Adjusted for peak force, total repetition rate, % duration all exertions.
¶Adjusted for peak force, total repetition rate, % duration all exertions, % time ≥30° wrist flexion.
HAL, hand-activity level.