Table 2. Shift Work and Risk of Coronary Heart Disease (CHD) in the NHS.
A total of 7,303 CHD cases (i.e. nonfatal myocardial infarction, CHD-attributed death, angiogram-confirmed angina pectoris, angioplasty, coronary artery bypass graft surgery, and coronary artery stents) occurred during 24 years of follow-up in NHS (n=73,623). Results represent hazard ratios (HR) with 95% confidence intervals (95%CI).
| Baseline history of rotating night shift worka | None | <5 years | 5 to 9 years | ≥ 10 years | p for trendb | p for interaction shift work * timec |
|---|---|---|---|---|---|---|
| NHS – 1988 to 2012 | ||||||
| cases/person-years | 2,739/643,774 | 2,857/644,857 | 568/103,574 | 1,139/173,571 | ||
| Incidence Rated per 100,000 person/years (95%) | 425.5 (383.9-467.1) | 435.1 (392.8-477.5) | 525.7 (410.4-641.1) | 596.9 (502.1-691.7) | ||
| Age-adjusted Model (HR, 95%CI) | 1.00 (Ref) | 1.02 (0.96-1.07) | 1.21 (1.11-1.33) | 1.36 (1.27-1.46) | <0.001 | |
| Multivariable-adjusted Modele (HR, 95%CI) | 1.00 (Ref) | 1.02 (0.97-1.08) | 1.12 (1.02-1.22) | 1.18 (1.10-1.26) | <0.001 | <0.001 |
| First vs. second half of follow-up | ||||||
| NHS – 06/1988- 05/2000 | 0.02 | |||||
| cases/person-years | 915/351,568 | 1,021/352,490 | 213/57,612 | 455/97,899 | ||
| Incidence Rated per 100,000 person/years (95%) | 367.3 (302.4-432.3) | 382.4 (316.8-448.1) | 483.1 (306.6-659.7) | 494.4 (370.1-618.8) | ||
| Multivariable-adjusted Modele (HR, 95%CI) | 1.00 (Ref) | 1.10 (1.01-1.21) | 1.19 (1.03-1.39) | 1.27 (1.13-1.42) | <0.001 | 0.03 |
| NHS – 06/2000-05/2012 | ||||||
| cases/person-years | 1,824/305,036 | 1,836/305,297 | 355/48,238 | 684/79,819 | ||
| Incidence Rated per 100,000 person/years (95% CI) | 436.6 (367.8-505.4) | 424.8 (361.8-487.7) | 520.7 (377.1-664.3) | 556.2 (414.2-754.3) | ||
| Multivariable-adjusted Modele (HR, 95%CI) | 1.00 (Ref) | 0.98 (0.92-1.05) | 1.08 (0.96-1.21) | 1.13 (1.04-1.24) | 0.004 | 0.08 |
| Restricted to MI and CHD death | ||||||
| NHS – 06/1988-05/2000 | ||||||
| cases/person-years | 443/353,659 | 491/354,846 | 117/58,026 | 226/99,022 | ||
| Incidence Rated per 100,000 person/years (95%) | 173.0 (128.3-217.8) | 182.3 (137.2-227.4) | 276.2 (142.6-409.9) | 236.5 (151.8-321.3) | ||
| Multivariable-adjusted Modele (HR, 95%CI) | 1.00 (Ref) | 1.12 (0.99-1.28) | 1.35 (1.10-1.66) | 1.29 (1.09-1.51) | 0.001 | 0.19 |
| NHS – 06/2000-05/2012 | ||||||
| cases/person-years | 444/316,989 | 428/318,083 | 65/50,714 | 176/84,689 | ||
| Incidence Rated per 100,000 person/years (95%) | 106.6 (73.1-140.0) | 92.3 (69.1-115.5) | 101.5 (36.4-166.5) | 133.3 (76.4-190.1) | ||
| Multivariable-adjusted Modele (HR, 95%CI) | 1.00 (Ref) | 0.95 (0.83-1.09) | 0.77 (0.60-1.00) | 1.09 (0.91-1.30) | 0.84 | 0.56 |
Assessed in 1988.
Based on category mid-points, except for 10+ years, where the mid-point was set to 10 years.
Based on the interaction between shift work category mid-points (except for 10+ years, where the mid-point was set to 10 years) and time (in 2-year cycles).
Incidence rates and confidence intervals are adjusted to the age distribution of women who reported no history of rotating night shift work, separately for each cohort.
Multivariable-adjusted model including age, physical activity (METs/h per week, in quintiles), diet (Alternative Healthy Eating Index [AHEI] score, Chiuve et al., 2012, in quintiles), alcohol consumption (none, 0.1-5, 5.1-10, 10.1-20, >20g/day) and pack-years of smoking (continuous), parental history of MI <60yrs (yes/no), menopausal status (pre/post), parity (nulliparous, 1 child, 2 children, ≥3 children), post-menopausal hormone use (ever, never, pre-menopausal), multivitamin use (yes/no), acetaminophen use (yes/no), NSAIDs use (yes/no) and aspirin use (yes/no), hypertension (yes/no), hypercholesterolemia (yes/no), diabetes (yes/no), body mass index (< 25, 25-29.9, 30-34.9, ≥35), race (white, black, other), and husbands' highest educational level (up to high school diploma, college degree, graduate school level or similar).