Table 5 Logistic regression models of consent to give blood, full sample, IP12

Feedback only, no covariates

1.38

1.16, 1.64

 < 0.001

Feedback

1.42

1.17, 1.72

 < 0.001

1.27

0.87, 1.86

0.2

1.38

1.15, 1.65

 < 0.001

1.38

1.16, 1.64

 < 0.001

1.27

0.86, 1.88

0.22

Final mode of interview (Ref: Nurse)

 Interviewer

0.21

0.16, 0.27

 < 0.001

0.19

0.13, 0.26

 < 0.001

0.19

0.13, 0.27

 < 0.001

 Web

0.13

0.10, 0.16

 < 0.001

0.11

0.08, 0.16

 < 0.001

0.11

0.08, 0.16

 < 0.001

Switcher dummy

0.61

0.46,0.80

 < 0.001

0.36

0.27, 0.46

 < 0.001

0.62

0.46, 0.81

 < 0.001

Feedback * Final mode of interview

 Feedback * Interviewer

1.10

0.68, 1.79

0.7

1.10

0.67, 1.80

0.71

 Feedback * Web

1.20

0.73, 1.98

0.5

1.19

0.71, 1.98

0.51

Age group (Ref: < 30)

 30–50

1.32

0.99, 1.77

0.06

1.20

0.87, 1.65

0.27

 50–70

1.99

1.50, 2.64

 < 0.001

2.02

1.49, 2.75

 < 0.001

 70 + 

2.03

1.42, 2.92

 < 0.001

1.92

1.30, 2.84

0.001

Sex (Ref: Male)

 Female

1.11

0.92, 1.32

0.27

1.12

0.92, 1.36

0.25

Country (Ref: England)

 Wales

0.83

0.55, 1.26

0.39

0.98

0.63, 1.51

 > 0.9

 Scotland

1.13

0.79, 1.63

0.51

1.01

0.68, 1.50

 > 0.9

Highest qualification (Ref: Degree)

 A-level/GCSE

0.83

0.68, 1.01

0.06

0.76

0.62, 0.94

0.01

 Other/None

0.82

0.61, 1.10

0.19

0.81

0.59, 1.11

0.19

In paid employment (Ref: Yes)

 No

0.93

0.75, 1.16

0.51

0.90

0.71, 1.14

0.40

Self-rated health (Ref: Excellent/Good)

 Fair/Poor

0.99

0.80, 1.22

0.94

0.96

0.76, 1.21

0.72

See NHS last 12 months (Ref: No)

 Yes

1.09

0.90, 1.31

0.38

1.05

0.86, 1.28

0.65

Time in study (Ref: Original IP1 sample)

 IP4/7/10 refreshment

1.02

0.84, 1.24

0.9

1.04

0.84, 1.30

0.70

 IP11 refreshment

1.04

0.81, 1.33

0.7

1.01

0.76, 1.33

 > 0.9