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Table 4 Final model for predicting 5-year breast cancer in the NHS cohorts and BWHS cohort

From: A model for predicting both breast cancer risk and non-breast cancer death among women > 55 years old

Predicting 5-year risk of breast cancer

NHS development cohort

NHS validation cohort

BWHS

Outcome being predicted

HR

P value

HR

P value

HR

P value

n = 37,628

n = 18,980

n = 13,247

N for that outcome

712

 

365

 

223

 

Factors in our final model

Age (per year increase)

1.01

0.10

1.01

0.41

1.02

0.15

Highest self-reported Body Mass Index (BMI) in past 10 years: (per kg/m2 increase)

1.03

< 0.001

1.02

0.008

1.02

0.01

Average alcohol use per day (highest average use in past 10 years): None

1

1

1

 1–4.9 g/day

1.12

0.27

0.99

0.95

0.79

0.17

 5–14.9 g/day

1.20

0.09

0.99

0.97

0.95

0.81

 15+ g/day

1.29

0.02

1.11

0.52

1.28

0.23

Age at menopause (years), < 45

0.91

0.57

0.64

0.07

1.08

0.74

 45–49

1

1

1

 50–54

1.21

0.04

1.18

0.20

1.15

0.44

 55+

1.32

0.05

1.13

0.53

1.08

0.78

Mammogram in past 2 years | No

1

1

1

 Yes

0.91

0.46

0.87

0.40

0.68

0.03

Number of breast biopsies, None

1

1

1

 1

1.38

 < 0.001

1.51

 < 0.001

1.28

0.12

 2+

1.31

0.16

1.64

0.04

1.14

0.53

Age at first birth (years) and parity, Nulliparous

1.25

0.23

0.98

0.95

1.10

0.66

 < 25, 1–2 children

1

1

1

 < 25, 3 + children

1.06

0.62

1.16

0.40

1.02

0.93

 25–29, 1–2 children

1.07

0.63

1.12

0.58

1.37

0.15

 25–29, 3 + children

1.04

0.76

1.08

0.68

1.60

0.17

 30+, 1–2 children

1.37

0.07

2.02

0.002

1.33

0.27

 30+, 3 + children

1.06

0.82

0.61

0.31

2.92

0.07

First-degree relatives with history of breast cancer and age at diagnosis, None

1

1

1

 1 and age < 50

1.43

0.03

1.30

0.28

1.21

0.56

 1 and age 50+

1.30

0.02

1.31

0.08

1.30

0.14

 2+ and at least one age < 50

2.19

0.003

3.27

< 0.001

1.60

0.51

 2+ and age 50+

2.43

< 0.001

1.53

0.31

0.39

0.35

Postmenopausal hormone use, Never

1

1

1

 Current estrogen + progestin user < 5 years

2.28

0.07

1.84

0.38

2.44

0.13

 Current estrogen + progestin user 5+ years

2.60

< 0.001

2.87

< 0.001

2.31

0.07

 Current estrogen-alone user < 5 years

1.60

0.15

1.42

0.50

1.88

0.14

 Current estrogen-alone user 5+ years

1.36

0.02

1.33

0.13

0.98

0.95

 Past estrogen + progestin user < 5 years

0.91

0.47

0.82

0.28

0.98

0.91

 Past estrogen + progestin user 5+ years

1.17

0.17

1.18

0.30

1.37

0.25

 Past estrogen-alone user < 5 years

1.01

0.93

0.78

0.31

1.04

0.84

 Past estrogen-alone user 5+ years

0.77

0.06

1.08

0.64

0.70

0.15

C-index (95% CI)

0.610 (0.589–0.631)

0.639 (0.611–0.667)

0.617 (0.582–0.652)

C-index (95% CI) when using risk factor regression coefficients from the NHS development cohort in the NHS and BWHS validation cohorts

0.612 (0.583–0.641)

0.573 (0.536–0.611)

  1. NHS = Nurses’ Health Study, BWHS = Black Women’s Health Study