Fully adjusted multivariate mixed model results with random intercepts for job within plant and person within job
| First aid injury and first aid MSD (n=2060) | Serious injury and serious MSD (n=658) | First aid MSD only (n=747) | Serious MSD only (n=264) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| RR* | 95% CI | Pr>F | RR* | 95% CI | Pr>F | RR* | 95% CI | Pr>F | RR* | 95% CI | Pr>F | |
| Sedentary/light physical demand | 1.00 | Reference | 0.0297 | 1.00 | Reference | 0.0052 | 1.00 | Reference | 0.0493 | 1.00 | Reference | 0.0206 |
| Medium physical demand | 1.26 | 1.02 to 1.55 | 1.41 | 1.04 to 1.90 | 1.26 | 0.95 to 1.69 | 1.13 | 0.71 to 1.79 | ||||
| Heavy/very heavy physical demand | 1.44 | 1.09 to 1.91 | 1.88 | 1.28 to 2.75 | 1.58 | 1.10 to 2.29 | 1.92 | 1.11 to 3.31 | ||||
| Never exposed to heat | 1.00 | Reference | 0.0034 | 1.00 | Reference | 0.1250 | 1.00 | Reference | 0.0165 | 1.00 | Reference | 0.2936 |
| Exposed to heat up to half the time | 1.38 | 1.07 to 1.77 | 1.21 | 0.89 to 1.66 | 1.57 | 1.11 to 2.22 | 1.43 | 0.91 to 2.23 | ||||
| Almost always exposed to heat | 1.78 | 1.27 to 2.49 | 1.57 | 1.02 to 2.42 | 1.87 | 1.19 to 2.92 | 1.38 | 0.73 to 2.61 | ||||
| Low psychological demand | 1.00 | Reference | 0.5428 | 1.00 | Reference | 0.0374 | 1.00 | Reference | 0.0929 | 1.00 | Reference | 0.0672 |
| Moderate psychological demand | 0.92 | 0.74 to 1.14 | 1.21 | 0.90 to 1.62 | 0.75 | 0.57 to 1.00 | 1.05 | 0.69 to 1.59 | ||||
| High psychological demand | 1.04 | 0.82 to 1.31 | 1.49 | 1.10 to 2.01 | 0.95 | 0.71 to 1.29 | 1.60 | 1.04 to 2.47 | ||||
| High job control | 1.00 | Reference | 0.0071 | 1.00 | Reference | 0.0937 | 1.00 | Reference | 0.2408 | 1.00 | Reference | 0.0977 |
| Moderate job control | 1.37 | 1.10 to 1.79 | 1.21 | 0.90 to 1.62 | 1.22 | 0.92 to 1.60 | 1.49 | 0.97 to 2.27 | ||||
| Low job control | 1.45 | 1.12 to 1.87 | 1.44 | 1.04 to 2.01 | 1.32 | 0.94 to 1.85 | 1.63 | 1.02 to 2.61 | ||||
| Race/ethnicity white | 1.00 | Reference | 0.5441 | 1.00 | Reference | 0.8664 | 1.00 | Reference | 0.1843 | 1.00 | Reference | 0.6487 |
| Other | 1.08 | 0.70 to 1.66 | 0.91 | 0.40 to 2.06 | 1.55 | 0.85 to 2.83 | 0.39 | 0.06 to 2.48 | ||||
| Hispanic | 1.18 | 0.94 to 1.48 | 1.12 | 0.77 to 1.63 | 1.34 | 0.96 to 1.88 | 1.23 | 0.70 to 2.18 | ||||
| Black | 0.99 | 0.84 to 1.17 | 1.08 | 0.84 to 1.38 | 1.05 | 0.82 to 1.36 | 1.07 | 0.74 to 1.56 | ||||
| Job tenure <1 year | 1.47 | 1.30 to 1.65 | <0.0001 | 1.33 | 1.08 to 1.64 | 0.0070 | 1.41 | 1.17 to 1.72 | 0.0004 | 1.55 | 1.13 to 2.12 | 0.0067 |
| Age | 0.99 | 0.98 to 0.99 | 0.0001 | 0.99 | 0.99 to 1.00 | 0.2615 | 0.99 | 0.98 to 1.00 | 0.0111 | 0.99 | 0.98 to 1.00 | 0.1426 |
| Female sex | 1.51 | 1.31 to 1.73 | <0.0001 | 1.55 | 1.23 to 1.93 | 0.0001 | 1.26 | 1.00 to 1.59 | 0.0462 | 1.75 | 1.25 to 2.46 | 0.0011 |
Psychological demand=(working fast+working without mistakes+working with conflicting demands).
Job control=(control over how job is done+control over when job is done).
*Adjusted for physical demand, heat exposure, psychological demand, job control, sex, age, job tenure <1 year, plant, manufacturing process, race/ethnicity with random intercepts for job within plant and person-within-job.
MSD, musculoskeletal disorder; RR, relative risk; Pr>F, significance test for fixed effects.