Table 1 Study population characteristics of the CT1 and CT2 chlamydia prevalence studies

Median age of participants, years (IQR)

40 (30, 51)

40 (30, 51)

31 (30, 39)

43 (33, 50)

43 (33, 50)

44 (30, 52)

Median age women, years (IQR)

40 (30, 50)

40 (30, 50)

32 (30, 42)

42 (33, 50)

42 (33, 50)

45 (36, 51)

Median age men, years (IQR)

41 (30, 52)

41 (30, 52)

30 (27, 31)

44 (34, 51)

44 (35, 51)

41 (32, 48)

Age group

 16–29 y/o—18–29 y/o

181 (24%)

178 (24%)

3 (27%)

125 (16%)

122 (16%)

3 (30%)

 30–44 y/o

279 (36%)

274 (36%)

5 (45%)

299 (39%)

297 (39%)

2 (20%)

 45–59 y/o

310 (40%)

307 (40%)

3 (27%)

339 (44%)

334 (44%)

5 (50%)

Gender

 Male

348 (45%)

343 (45%)

5 (45%)

351 (46%)

348 (46%)

3 (30%)

 Female

422 (55%)

416 (55%)

6 (55%)

412 (54%)

405 (54%)

7 (70%)

Nationality

 Belgian

–

–

–

639 (84%)

630 (84%)

9 (90%)

 Other than Belgian

–

–

–

124 (16%)

123 (16%)

1 (10%)

Education

 No diploma or primary education

28 (4%)

28 (4%)

0 (0%)

30 (4%)

30 (4%)

0 (0%)

 Lower secondary education

45 (6%)

45 (6%)

0 (0%)

73 (10%)

71 (9%)

2 (20%)

 Higher secondary education

175 (23%)

172 (23%)

3 (27%)

225 (29%)

223 (30%)

2 (20%)

 Higher education (academic or outside University)

456 (59%)

449 (59%)

7 (64%)

382 (50%)

379 (50%)

3 (30%)

 No answer

66 (9%)

65 (9%)

1 (9%)

53 (7%)

50 (7%)

3 (30%)

Health literacy

 Low

–

–

–

25 (3%)

24 (3%)

1 (10%)

 Limited

–

–

–

209 (27%)

207 (27%)

2 (20%)

 Sufficient

–

–

–

472 (62%)

466 (62%)

6 (60%)

 No answer

–

–

–

57 (7%)

56 (7%)

1 (10%)

Civil status

 Single (never married)

–

–

–

220 (29%)

215 (29%)

5 (50%)

 Married or legal cohabitation

–

–

–

461 (60%)

460 (61%)

1 (10%)

 Divorced (not remarried)

–

–

–

78 (10%)

74 (10%)

4 (40%)

 Widowed (not remarried)

–

–

–

4 (1%)

4 (1%)

0 (0%)

Sexual intercourse in the last 12 months

 Yes

635 (82%)

625 (82%)

10 (91%)

600 (79%)

593 (79%)

7 (70%)

 No

68 (9%)

67 (9%)

1 (9%)

103 (13%)

101 (13%)

2 (20%)

 No answer

62 (8%)

62 (8%)

0 (0%)

60 (8%)

59 (8%)

1 (10%)

Nr. of sexual partner in the last 12 months

 One

532 (69%)

526 (69%)

6 (55%)

541 (71%)

535 (71%)

6 (60%)

 Two

38 (5%)

38 (5%)

0 (0%)

25 (3%)

24 (3%)

1 (10%)

 Three

34 (4%)

34 (4%)

0 (0%)

21 (3%)

21 (3%)

0 (0%)

 Four or more

27 (4%)

24 (3%)

3 (27%)

11 (1%)

11 (1%)

0 (0%)

 No answer

136 (18%)

134 (18%)

2 (18%)

165 (22%)

162 (22%)

3 (30%)

The last sexual partner was…

 A steady partner

557 (72%)

552 (73%)

5 (45%)

–

–

–

 A casual partner

74 (10%)

70 (9%)

4 (36%)

–

–

–

 No answer

136 (18%)

134 (18%)

2 (18%)

–

–

–

Condom use during last intercourse

 No

525 (68%)

518 (68%)

7 (64%)

510 (67%)

503 (67%)

7 (70%)

 Yes

–

–

–

88 (12%)

88 (12%)

0 (0%)

 Yes, the whole time

65 (8%)

64 (8%)

1 (9%)

–

–

–

 Yes, but not the whole time

44 (6%)

43 (6%)

1 (9%)

–

–

–

 No answer

136 (18%)

134 (18%)

2 (18%)

165 (22%)

162 (22%)

3 (30%)

First sexual intercourse before age 15

 Yes

33 (5%)

33 (5%)

0 (0%)

32 (4%)

31 (4%)

1 (10%)

 No

672 (95%)

661 (95%)

11 (100%)

631 (83%)

623 (83%)

8 (80%)

 No answer

65 (8%)

65 (9%)

0 (0%)

100 (13%)

99 (13%)

1 (10%)

Median age at first sexual intercourse, years (IQR)

18 (16, 20)

18 (16, 20)

19 (18, 19)

18 (16, 20)

18 (16, 20)

17 (16, 18)

Ever been tested for any STI

 Yes

278 (36%)

272 (36%)

6 (55%)

–

–

–

 No

412 (54%)

408 (54%)

4 (36%)

–

–

–

 No answer

60 (8%)

59 (8%)

1 (9%)

–

–

–

Ever been diagnosed with chlamydia

 Yes

27 (4%)

27 (4%)

0 (0%)

–

–

–

 No

686 (89%)

675 (89%)

11 (100%)

–

–

–

 No answer

57 (7%)

57 (8%)

0 (0%)

–

–

–

Sexual orientation for men

 Men who are attracted to men only/mostly/as much as to women

29 (8%)

29 (8%)

0 (0%)

–

–

–

Testing for HIV in the past 12 months

 Yes

–

–

–

53 (7%)

52 (7%)

1 (10%)

 No

–

–

–

655 (86%)

647 (86%)

8 (80%)

 No answer

–

–

–

55 (7%)

54 (7%)

1 (10%)

Ever been tested for HIV

 Yes

–

–

–

303 (40%)

300 (40%)

3 (30%)

 No

–

–

–

405 (53%)

399 (53%)

6 (60%)

 No answer

–

–

–

55 (7%)

54 (7%)

1 (10%)

Testing for other STI than HIV in the past 12 months

 Yes

–

–

–

60 (8%)

59 (8%)

1 (10%)

 No

–

–

–

608 (80%)

600 (80%)

8 (80%)

 No answer

–

–

–

95 (12%)

94 (12%)

1 (10%)

Ever been tested for other STI than HIV

 Yes

–

–

–

321 (42%)

318 (42%)

3 (30%)

 No

–

–

–

347 (45%)

341 (45%)

6 (60%)

 No answer

–

–

–

95 (12%)

94 (12%)

1 (10%)