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Table 1 Determinants of providing a cell phone number by responders, per screening round

From: Keeping participants on board: increasing uptake by automated respondent reminders in an Internet-based Chlamydia Screening in the Netherlands

Package requests (N)

Multivariate logistic regression

 

Round 1 (N = 52628)

Round 2 (N = 41729)

 

n (%)

OR (95%CI)

p-value

n (%)

OR (95%CI)

p-value

Cell phone number providers (n)

37,375

  

30,510

  

Gender

37,375

  

30,510

  

   Male

33.2

1.0

 

32.3

NA

NA

   Female

68.8

1.2 (1.0-1.4)

0.008

67.7

  

Age

37,374

  

30,510

  

   16-19

14.7

1.0

 

15.1

1.0

 

   20-24

39.2

1.0 (1.0-1.1)

0.23

40.4

1.1 (1.0-1.2)

0.08

   25-29

46.1

0.8 (0.8-0.9)

< 0.001

44.5

0.8 (0.8-0.9)

< 0.001

Ethnicity

37,374

  

30,510

  

   Dutch

61.2

1.0

 

60.1

1.0

 

   Surinam/Antillean

11.8

1.3 (1.2-1.4)

< 0.001

11.5

1.3 (1.2-1.4)

< 0.001

   Turkish/Moroccan

6.4

1.1 (1.0-1.2)

0.04

6.3

1.1 (1.0-1.2)

0.09

   Sub Sahara African

3.4

1.5 (1.3-1.8)

< 0.001

4.1

1.7 (1.5-2.0)

< 0.001

   Western, other

8.0

1.0 (0.9-1.1)

0.66

8.6

1.0 (0.9-1.1)

0.87

   Non-Western, other

9.2

1.1 (1.1-1.2)

0.002

9.4

1.2 (1.1-1.3)

< 0.001

Region

37,375

  

30,510

  

   Rotterdam

57.4

ns

ns

55.0

1.0

 

   Amsterdam

39.3

  

38.3

1.0 (0.9-1.0)

0.35

   South-Limburg

3.3

  

6.7

0.8 (0.7-0.9)

< 0.001

Community risk level

37,375

  

30,510

  

   Low

34.9

1.0

 

34.4

1.0

 

   Medium

50.1

0.9 (0.8-0.9)

< 0.001

49.0

0.9 (0.9-1.0)

0.006

   High

15.0

1.0 (0.9-1.0)

0.24

16.6

0.9 (0.9-1.1)

0.82

Educational level

23,229

  

17,172

  

   Low

5.0

1.0

 

4.9

1.0

 

   Medium

28.7

0.9 (0.8-1.0)

0.17

28.8

1.0 (0.8-1.2)

0.74

   High

66.3

0.8 (0.7-0.9)

0.007

66.3

0.8 (0.7-1.0)

0.05

Ethnicity SP

13,998

  

9,638

  

   Concordant(NL/NL)

54.8

1.0

 

54.1

ns

ns

   Discordant (NL/non-NL)

26.9

1.0 (0.9-1.1)

0.55

26.7

  

   Concordant (non-NL/non-NL)

18.3

1.4 (1.2-1.5)

< 0.001

19.2

  

Age at first sexual contact

22,728

  

16,752

  

   ≤5

29.3

1.0

 

30.6

1.0

 

   16-18

52.6

0.8 (0.8-0.9)

< 0.001

52.9

0.8 (0.8-0.9)

< 0.001

   ≥ 19

18.1

0.7 (0.6-0.8)

< 0.001

16.5

0.6 (0.6-0.7)

< 0.001

Number of sexual partners < 6 months

22,459

  

16,612

  

   No partner(s)

8.5

1.0

 

7.9

ns

ns

   1 steady partner

49.4

1.2 (1.0-1.5)

0.12

44.5

  

   1 casual partner

11.7

1.2 (1.0-1.5)

0.16

13.0

  

   ≥ 2 partners (incl. steady partner)

30.4

1.5 (1.1-1.9)

0.003

34.6

  

Duration steady partnership

22,812

  

16,841

  

   < 1 year

15.9

1.0

 

17.7

1.0

 

   1-2 years

20.9

1.0 (0.9-1.1)

0.62

19.5

1.0 (0.9-1.1)

0.18

   3-5 years

15.0

0.8 (0.7-0.9)

< 0.001

12.7

0.9 (0.8-1.0)

0.01

   ≥ 6 years

9.1

0.8 (0.7-0.8)

< 0.001

6.9

0.7 (0.6-0.8)

< 0.001

   No steady partner

39.1

1.5 (0.9-2.4)

0.13

43.2

0.8 (0.7-0.9)

0.001

Condom use last contact CP

8,124

  

6,926

  

   Yes

47.7

1.0

 

44.0

1.0

 

   No

52.3

1.2 (1.1-1.3)

< 0.001

56.0

1.1 (1.1-1.3)

0.02

Condom use last contact SP

13,876

  

9,547

  

   Yes

15.8

1.0

 

16.0

NA

NA

   No

84.2

1.2 (1.1-1.3)

< 0.001

84.0

  

History of STI

3,175

  

8,442

  

   No STI ever

68.1

1.0

 

68.8

1.0

 

   Yes, < 6 months

4.0

1.2 (0.8-2.0)

0.38

4.0

1.2 (0.9-1.5)

0.25

   Yes, ≥ 6 months

27.9

1.2 (1.0-1.5)

0.03

27.2

1.2 (1.1-1.3)

0.002

Symptoms of an STI

5,649

  

13,284

  

   Yes

38.1

ns

ns

40.1

1.0

 

   No

61.9

  

59.9

0.7 (0.8-0.9)

< 0.001

  1. OR, odds ratio; CI, confidence interval; NA, not applicable (p ≥ 0.2 in univariate analysis); ns, not significant (p > 0.05 in multivariate analysis); MSM, men having sex with men, STI, sexually transmitted infection(s); SP, steady partner; CP, casual partner. Ethnicity 'Western other' included Oceania, North America, Canada, Europe (excluding the Netherlands and Turkey); 'Non Western other' included Central and South America, Middle East, South and South-East Asia (excluding Surinam, Antilles, Aruba, Morocco and North Africa). Non-significant variables in the multivariate models in both screening rounds are not shown: SES-score, living situation, concurrent partners, sexual preference, history of STI testing