Table 1 Uptake of screening and prevalence of chlamydia according to effort needed to secure participation

Groups by sex and age
 Effort needed
 No of people who received this form of invitation to be screened
 No of people who responded after each form of invitation*
 % uptake (95% CI)
 % cumulative uptake (95% CI)
 No of cases
 Prevalence (95% CI)
 P value for linear trend calculated from Wald test
 Cumulative prevalence (95% CI)
All
Single postal invitation
14 382
3239
25.0 (21.7 to 28.6)
25.0 (21.7 to 28.6)
137
3.0 (2.3 to 3.9)
0.014
3.0 (2.3 to 3.9)

Two postal invitations
11 143
683
5.3 (3.9 to 7.1)
30.3 (26.5 to 34.3)
32
3.4 (2.1 to 5.4)

3.1 (2.3 to 4.0)

Phone call
10 460
53
0.5 (0.1 to 2.2)
30.8 (26.9 to 35.0)
2
2.0 (1.1 to 3.8)

3.0 (2.3 to 3.9)

Home visit or flagging{dagger}
 10 407
765
3.7 (2.0 to 6.8)
34.5 (31.2 to 38.0)
48
5.0 (3.4 to 7.2)

3.2 (2.5 to 4.2)
All 16-24
Single postal invitation
11 245
2436
22.2 (18.6 to 26.2)
22.2 (18.6 to 26.2)
133
5.4 (4.3 to 6.6)
0.054
5.4 (4.3 to 6.6)

Two postal invitations
8809
507
4.3 (3.0 to 6.2)
26.5 (22.6 to 30.8)
29
6.5 (4.7 to 8.9)

5.5 (4.6 to 6.7)

Phone call
8302
39
0.5 (0.1 to 2.2)
27.0 (22.9 to 31.5)
2
4.4 (2.8 to 6.8)

5.5 (4.6 to 6.7)

Home visit or flagging{dagger}
 8263
627
4.6 (2.0 to 10.0)
31.5 (28.6 to 34.6)
45
7.4 (5.5 to 9.9)

5.8 (4.9 to 6.9)
Men 16-24
Single postal invitation
5454
1017
18.9 (16.0 to 22.3)
18.9 (16.0 to 22.3)
46
5.4 (4.4 to 6.5)
0.768
5.4 (4.4 to 6.5)

Two postal invitations
4437
196
3.57 (2.6 to 4.9)
22.5 (19.3 to 26.1)
9
5.3 (2.8 to 9.8)

5.4 (4.3 to 6.6)

Phone call
2241
21
0.49 (0.1 to 2.5)
23.0 (19.6 to 26.8)
0
0.0 (0.0 to 0.1)

5.2 (4.2 to 6.5)

Home visit or flagging{dagger}
 4220
243
3.61 (1.5 to 8.3)
26.6 (24.0 to 29.4)
12
5.4 (3.3 to 8.8)

5.3 (4.4 to 6.3)
Women 16-24
Single postal invitation
5791
1419
25.3 (20.9 to 30.3)
25.3 (20.9 to 30.3)
76
5.3 (3.9 to 7.3)
0.033
5.3 (3.9 to 7.3)

Two postal invitations
4372
311
5.1 (3.4 to 7.7)
30.4 (25.7 to 35.6)
20
7.3 (4.8 to 11.0)

5.7 (4.3 to 7.5)

Phone call
4061
18
0.4 (0.1 to 2.0)
30.9 (26.0 to 36.2)
2
9.5 (5.8 to 15.2)

5.7 (4.4 to 7.4)

Home visit or flagging{dagger}
 4043
384
5.5 (2.5 to 11.9)
36.4 (33.1 to 39.8)
33
8.7 (6.8 to 11.1)

6.2 (4.9 to 7.8)

* Includes nine people who returned a consent form but no specimen.

{dagger} A "flag" was attached to patients' notes. Patients attending the practice during the study period were invited again to take part if they had not already participated, declined to participate, or been confirmed not resident at their address.