Table 3.
Mean values of brachial FMD (%) by hours of work per week, occupational categories, and job strain.
| N | Model 1 | Model 2 | Model 3 | Model 4 | |
|---|---|---|---|---|---|
| Work hours/week | |||||
| <40 | 504 | 4.44 ± 0.13 | 4.65 ± 0.13 | 4.65 ± 0.13 | 4.61 ± 0.24 |
| 40 | 463 | 5.07 ± 0.15 | 4.94 ± 0.14 | 4.95 ± 0.14 | 4.95 ± 0.25 |
| 41-50 | 211 | 4.96 ± 0.23 | 4.91 ± 0.22 | 4.87 ± 0.22 | 4.91 ± 0.34 |
| ≥50 | 321 | 4.96 ± 0.16 | 4.88 ± 0.16 | 4.87 ± 0.16 | 4.88 ± 0.28 |
| P-value1 | 0.001 | 0.413 | 0.289 | 0.157 | |
| Occupational categories | |||||
| Mgt./Professional | 722 | 4.93 ± 0.12 | 4.99 ± 0.11 | 4.96 ± 0.12 | 4.97 ± 0.22 |
| Sales/Office | 294 | 5.29 ± 0.20 | 5.35 ± 0.19 | 5.16 ± 0.18 | 5.19 ± 0.28 |
| Services | 249 | 4.69 ± 0.18 | 4.66 ± 0.17 | 4.79 ± 0.19 | 4.73 ± 0.29 |
| Blue-collar | 234 | 3.96 ± 0.17 | 3.96 ± 0.15 | 3.96 ± 0.16 | 4.01 ± 0.26 |
| P-value2 | <0.001 | <0.001 | <0.001 | <0.001 | |
| Job strain | |||||
| HC/HD | 334 | 5.18 ± 0.16 | 5.12 ± 0.15 | 4.92 ± 0.15 | 4.90 ± 0.26 |
| HC/LD | 340 | 4.35 ± 0.15 | 4.71 ± 0.16 | 4.66 ± 0.16 | 4.67 ± 0.26 |
| LC/HD | 437 | 5.21 ± 0.16 | 4.87 ± 0.16 | 4.97 ± 0.16 | 4.95 ± 0.26 |
| LC/LD | 381 | 4.47 ± 0.15 | 4.61 ± 0.14 | 4.69 ± 0.14 | 4.71 ± 0.24 |
| P-value2 | <0.001 | 0.088 | 0.388 | 0.518 | |
| Job control | −0.002, 0.673 | 0.008, 0.115 | 0.001, 0.875 | −0.002, 0.673 | |
| Job demands | 0.058, <0.001 | 0.024, 0.026 | 0.017, 0.104 | 0.016, 0.132 |
Job strain categories are: High control/high demands; high control/low demands; low control/high demands; low control/low demands.
Results for the categorical variables are mean ± SEM.
Results for ‘job control’ and ‘job demands’ are β-coefficients and P-values.
P-values were obtained from linear regression models.
P-values were obtained from ANOVA/ANCOVA models.
Model 1: Unadjusted.
Model 2: Adjusted for age and gender.
Model 3: Adjusted for age, gender, race/ethnicity, educational level, waist circumference, HDL cholesterol, and total cholesterol.
Model 4: Adjusted for age, gender, race/ethnicity, educational level, waist circumference, HDL cholesterol, total cholesterol, BMI, diastolic blood pressure, systolic blood pressure, physical activity, smoking status, and pack-years of smoking.
Gender was not included in any of the models for ‘occupational categories’ because gender is a significant effect modifier in the association between occupational categories and FMD % (see Table 4).
Occupational categories, Model 4:
Management/Professional vs. Sales/Office: P=0.801
Management/Professional vs. Services: P=0.771
Management/Professional vs. Blue-collar: P <0.001
Services vs. Sales/Office: P=0.293
Services vs. Blue-collar: P=0.012
Sales/Office vs. Blue-collar: P <0.001