Table 4.
Associations of time since stopping rotating night shift work and invasive breast cancer during 24 years of follow-up in NHS II only (1989–2013)
| No. of cases | Person-years | Age-adjusted HR (95%CI) |
Multivariable-adjusted HR (95% CI)a |
|
|---|---|---|---|---|
| NHS II time since stopping rotating night shift work among all | ||||
| Never shift work | 1060 | 786,772 | Ref | Ref |
| Current shift work | 478 | 467,992 | 0.97 (0.87–1.09) | 0.96 (0.84–1.09) |
| Past, <=8 years since stopping shift work | 798 | 606,237 | 1.01 (0.92–1.11) | 1.02 (0.91–1.13) |
| Past, 9–16 years since stopping shift work | 907 | 476,794 | 1.08 (0.98–1.19) | 1.10 (0.99–1.22) |
| Past, >16 years since stopping shift work | 327 | 233,060 | 1.09 (0.94–1.27) | 1.10 (0.95–1.28) |
|
|
||||
| 3570 | 2,570,855 | |||
| NHS II time since stopping rotating night shift work, restricted to ever rotating night shift workers only | ||||
| Current shift work (i.e. 0 years since stopping) | 478 | 467,992 | Ref | Ref |
| Past, <=8 years since stopping shift work | 798 | 606,237 | 1.03 (0.92–1.17) | 1.05 (0.93–1.19) |
| Past, 9–16 years since stopping shift work | 907 | 476,794 | 1.11 (0.97–1.27) | 1.14 (0.99–1.31) |
| Past, >16 years since stopping shift work | 327 | 233,060 | 1.17 (0.96–1.43) | 1.19 (0.96–1.46) |
|
|
||||
| 2510 | 1,784,083 | Ptrend=0.06 | Ptrend=0.05 | |
a
Multivariable-adjusted models are adjusted for the covariates listed in Table 2 footnotes, and are additionally adjusted for duration of rotating night shift work (continuous in months).