Table 4. Shift Work and CHD in women without diabetes, hypertension and hypercholesterolemia.
All women who reported any of those comorbidities at baseline, or throughout follow-up, were excluded from those analyses, both in NHS (n= 43,557) and NHS2 (n=98,126). Results represent hazard ratios (HR) with 95% confidence intervals (95%CI). MI=myocardial infarction.
| Cohort | Baseline history of rotating night shift worka | p for trendb | p for interaction shift work* timec | |||
|---|---|---|---|---|---|---|
| NHS – 1988-2012 | None | <5 years | 5 to 9 years | ≥ 10 years | ||
| cases/person-years | 723/319,135 | 791/316,198 | 157/47,860 | 260/75,528 | ||
| Incidence Rated per 100,000 person/years (95%CI) | 301.4 (243.5-359.2) | 323.7 (263.0-384.4) | 409.4 (238.3-580.5) | 380.0 (255.1-504.9) | ||
| Age-adjusted Model (HR, 95%CI) | 1.00 (Ref) | 1.06 (0.96-1.18) | 1.37 (1.15-1.63) | 1.36 (1.17-1.57) | <0.001 | |
| Multivariable-adjusted Modele (HR, 95%CI) | 1.00 (Ref) | 1.08 (0.97-1.19) | 1.29 (1.08-1.54) | 1.17 (1.01-1.36) | 0.004 | 0.24 |
| NHS2 – 1989-2013 | ||||||
| cases/person-years | 720/748,075 | 1,001/966,924 | 193/165,593 | 134/92,148 | ||
| Incidence Rated per 100,000 person/years (95%CI) | 100.6 (81.1-120.2) | 112.1 (93.6-130.7) | 122.9 (74.3-171.5) | 136.8 (78.8-194.9) | ||
| Age-adjusted Model (HR, 95%CI) | 1.00 (Ref) | 1.09 (0.99-1.20) | 1.17 (1.00 -1.38) | 1.28 (1.06-1.54) | 0.003 | |
| Multivariable-adjusted Modele (HR, 95%CI) | 1.00 (Ref) | 1.09 (0.99-1.20) | 1.10 (0.94 -1.30) | 1.13 (0.94 -1.36) | 0.11 | 0.78 |
Assessed in 1988 for NHS and in 1989 for NHS2.
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 standardized 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), parity (nulliparous, 1 child, 2 children or ≥3 children), menopausal status (pre/post), 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), race (white, black, or other), husbands' highest educational level (up to high school diploma, college degree, or graduate school level or similar) and body mass index (< 25, 25-29.9, 30-34.9, ≥35).