Table 3 Age-adjusted and multivariable hazard ratios (95% confidence intervals) of incident breast cancer according job category and occupational activity after stratification by daily walking time

1. Manual

Number at risk

5755

2099

3071

Number of breast cancer

38

23

23

Person-years

80,397

28,710

41,034

Age-adjusted HR (95%CI)

1.00 (reference)

1.00 (reference)

1.00 (reference)

Multivariable OR (95%CI)^a

1.00 (reference)

1.00 (reference)

1.00 (reference)

2. Office

Number at risk

826

568

855

Number of breast cancer

11

8

12

Person-years

11,861

7895

11,626

Age-adjusted HR (95%CI)

1.15 (0.98–1.34)

1.14 (0.98–1.31)

1.17 (1.01–1.23)

Multivariable OR (95%CI)^a

1.12 (0.95–1.32)

1.12 (0.97–1.30)

1.11 (1.01–1.23)

3. Professional

Number at risk

2211

622

609

Number of breast cancer

8

4

6

Person-years

29,219

8127

7907

Age-adjusted HR (95%CI)

0.92 (0.82–1.02)

0.99 (0.88–1.13)

1.04 (0.95–1.14)

Multivariable OR (95%CI)^a

0.92 (0.83–1.02)

0.96 (0.83–1.12)

1.04 (0.95–1.14)

4. Unclassified

Number at risk

384

165

244

Number of breast cancer

1

0

0

Person-years

4031

1532

2264

Age-adjusted HR (95%CI)

0.93 (0.76–1.13)

NA

NA

Multivariable OR (95%CI)^a

0.96 (0.79–1.17)

NA

NA

p for interaction

0.03

1. Moving

Number at risk

3768

1215

1956

Number of breast cancer

26

11

11

Person-years

52,811

16,989

26,395

Age-adjusted HR (95%CI)

1.00 (reference)

1.00 (reference)

1.00 (reference)

Multivariable OR (95%CI)^a

1.00 (reference)

1.00 (reference)

1.00 (reference)

2. Standing

Number at risk

729

520

513

Number of breast cancer

7

7

795

Person-years

10,333

7138

12

Age-adjusted HR (95%CI)

NA

0.80 (0.11–5.77)

1.56 (0.49–4.98)

Multivariable OR (95%CI)^a

NA

NA

1.56 (0.49–4.99)

3. Sitting

Number at risk

4679

1719

2028

Number of breast cancer

25

17

18

Person-years

62,365

22,138

25,777

Age-adjusted HR (95%CI)

1.51 (0.93–2.43)

2.12 (1.24–3.63)

1.84 (1.14–2.97)

Multivariable OR (95%CI)^a

1.38 (0.85–2.27)

1.87 (1.07–3.27)

1.74 (1.07–2.83)

p for interaction

0.006