The effect of including covariates on hazard ratios for ischaemic heart disease according to work pressure among nurses participating in the Danish Nurse Cohort Study, 1993–2008
| Characteristics | Basic model A*,§ | Model B†,§ | Model C‡,§ | |||
| HR | 95% CI | HR | 95% CI | HR | 95% CI | |
| Work pressure | ||||||
| Much/a little too low | 1.44 | 0.64 to 3.25 | 1.51 | 0.66 to 3.42 | 1.45 | 0.63 to 3.29 |
| Suitable | 1 | 1 | 1 | |||
| A little too high | 1.25 | 1.04 to 1.50 | 1.24 | 1.02 to 1.50 | 1.26 | 1.03 to 1.53 |
| Much too high | 1.47 | 1.14 to 1.88 | 1.35 | 1.03 to 1.76 | 1.38 | 1.04 to 1.81 |
| Job influence | ||||||
| Major influence | 1 | |||||
| Some influence | 1.02 | 0.86 to 1.22 | ||||
| Minor or no influence | 1.01 | 0.76 to 1.34 | ||||
| Family history of IHD | ||||||
| No | 1 | 1 | 1 | |||
| Yes | 2.12 | 1.62 to 2.78 | 2.01 | 1.50 to 2.70 | 2.01 | 1.49 to 2.68 |
| Not known | 1.44 | 1.13 to 1.84 | 1.36 | 1.05 to 1.76 | 1.34 | 1.03 to 1.72 |
| Diabetes | ||||||
| No | 1 | 1 | 1 | |||
| Yes | 4.65 | 2.97 to 7.27 | 4.31 | 2.67 to 6.94 | 4.30 | 2.67 to 6.93 |
| Menopausal status | ||||||
| Pre-menopausal | 1 | 1 | 1 | |||
| Postmenopausal | 1.41 | 1.10 to 1.80 | 1.22 | 0.94 to 1.58 | 1.21 | 0.94 to 1.58 |
| BMI | ||||||
| <25 | 1 | 1 | 1 | |||
| 25≤BMI<30 | 1.21 | 1,00 to 1.47 | 1.20 | 0.98 to 1.48 | 1.19 | 0.96 to 1.45 |
| ≥30 | 1.75 | 1.29 to 2.37 | 1.71 | 1.24 to 2.35 | 1.69 | 1.23 to 2.33 |
| Smoker | ||||||
| Never/former | 1 | 1 | 1 | |||
| Current | 1.50 | 1.27 to 1.78 | 1.57 | 1.31 to 1.87 | 1.55 | 1.30 to 1.84 |
| Alcohol intake | ||||||
| No intake | 1.33 | 1.06 to 1.65 | 1.30 | 1.03 to 1.63 | 1.25 | 0.99 to 1.57 |
| 1–28 units/week | 1 | 1 | 1 | |||
| >28 units/week | 1.25 | 0.98 to 1.60 | 1.19 | 0.92 to 1.54 | 1.20 | 0.93 to 1.55 |
| Leisure time physical activity | ||||||
| >4 h/week hard | 1 | 1 | 1 | |||
| ≤4 h/week moderate | 1.10 | 0.91 to 1.38 | 1.16 | 0.94 to 1.43 | 1.19 | 0.96 to 1.45 |
| Sedentary | 1.63 | 1.16 to 2.28 | 1.47 | 1.02 to 2.12 | 1.52 | 1.05 to 2.18 |
| Shift work | ||||||
| Day | 1 | 1 | ||||
| Evening | 1.05 | 0.82 to 1.35 | 0.94 | 0.71 to 1.24 | ||
| Night | 1.44 | 1.11 to 1.87 | 1.19 | 0.86 to 1.63 | ||
| Rotate | 0.91 | 0.72 to 1.15 | 0.81 | 0.63 to 1.04 | ||
| Physical activity at work | ||||||
| Sedentary/not physically exerting | 1 | 1 | ||||
| Physically exerting/strenuous | 1.36 | 1.15 to 1.61 | 1.28 | 1.05 to 1.54 | ||
BMI, body mass index; HR, hazard ratio; IHD, ischemic heart disease.
↵* Adjusted for age.
↵† Adjusted for age and risk factors for IHD (family history of IHD, diabetes, menopausal status, BMI, smoking, alcohol consumption, leisure time physical activity).
↵‡ Adjusted for age, risk factors for IHD, shift work and physical activity at work.
↵§ The type 3 test for work pressure in the Cox models was: p=0.012 in model A, p=0.066 in model B and p=0.059 in model C.