Table 3 Multivariable Cox regression analysis modelling the independent effect of additional bevacizumab on the risk of death, adjusted for all factors listed

Age (years)

  < 60

Ref

Ref

 60–74

1.0

0.76–1.38

0.86

1.8

1.82–4.13

0.15

  ≥ 75

1.3

0.87–1.90

0.21

0.8

0.20–3.53

0.80

Comorbidity

 No

Ref

Ref

 1 comorbid condition

0.9

0.69–1.22

0.56

1.1

0.40–2.86

0.88

  ≥ 2 comorbid conditions

0.8

0.54–1.04

0.08

1.0

0.34–3.01

1.07

 Unknown

0.7

0.47–1.17

0.19

0.6

0.21–1.98

1.00

Primary tumor localization

 Rectum

Ref

Ref

 Colon

1.3

1.01–1.65

<0.05

0.6

0.21–1.98

0.35

Adjuvant chemotherapy

 No

Ref

Ref

 Yes

1.0

0.82–1.34

0.68

1.0

0.44–2.32

0.97

Time to metastases (years)

  < 1 year

Ref

Ref

 1–2 years

1.1

0.87–1.57

0.28

0.7

0.25–1.87

0.46

  ≥ 2 years

1.0

0.72–1.31

0.85

0.4

0.16–1.22

0.11

Period of diagnosis metastasis

 2005–2006

Ref

Ref

 2007–2008

1.1

0.81–1.64

0.42

2.3

0.64–8.34

0.20

 2009–2011

1.1

0.78–1.71

0.47

2.5

0.67–9.62

0.16

Number of organs affected

 1 organ

Ref

Ref

 2 organs

1.2

0.96–1.63

0.19

1.8

0.74–4.78

0.18

  ≥ 3 organs

1.6

1.12–2.21

<0.01

4.3

1.48–13.00

<0.01

First-line chemotherapy

 Single agent chemotherapy

Ref

Ref

 Combination chemotherapy

0.9

0.69–1.27

0.69

0.2

0.07–0.49

<0.001

Additional bevacizumab

 No

Ref

 Yes

0.6

0.49–0.89

<0.01

0.3

0.14–0.79

<0.05

Number of systemic lines

 1 line

Ref

 2 lines

0.6

0.44–0.84

<0.01

0.5

0.16–1.74

0.29

  ≥ 3 lines

0.4

0.31–0.58

<0.0001

0.3

0.13–0.72

<0.01