Sociodemographic characteristics and sexual risk factors of the study population (15–39 years old) in 1996, 2007 and 2017
| Characteristics | 1996 | 2007 | 2017 | 1996 vs 2007 | 2007 vs 2017 | 1996 vs 2017 |
| N (%) | N (%) | N (%) | P value | P value | P value | |
| Total | 1568 (100) | 1590 (100) | 1146 (100) | |||
| Fully observed variables | ||||||
| Sex | >0.9 | <0.001 | <0.001 | |||
| Female | 953 (61) | 966 (61) | 562 (49) | |||
| Male | 615 (39) | 624 (39) | 584 (51) | |||
| Age | 0.6 | <0.001 | <0.001 | |||
| 15–24 | 589 (38) | 610 (38) | 430 (27) | |||
| 25–39 | 979 (62) | 980 (62) | 716 (46) | |||
| Migration background* | <0.001 | 0.024 | <0.001 | |||
| Dutch | 1386 (88) | 1320 (83) | 944 (82) | |||
| Moroccan or Turkish | 41 (2.6) | 41 (2.6) | 21 (1.8) | |||
| SAN | 24 (1.5) | 40 (2.5) | 76 (6.6) | |||
| Western, non-Dutch | 98 (6.2) | 120 (7.5) | 33 (2.9) | |||
| Non-Western | 19 (1.2) | 69 (4.3) | 72 (6.3) | |||
| Urbanisation | <0.001 | <0.001 | <0.001 | |||
| (Very) low | 765 (49) | 344 (22) | 339 (30) | |||
| Moderate and high | 803 (51) | 1246 (78) | 807 (70) | |||
| Variables with missing data | ||||||
| Education† | <0.001 | <0.001 | <0.001 | |||
| Practical | 1153 (74) | 1107 (70) | 652 (57) | |||
| Theoretical | 246 (16) | 464 (29) | 420 (37) | |||
| Unknown | 169 (11) | 19 (1.2) | 74 (6.5) | |||
| Sexual practice‡ | >0.9 | – | – | |||
| Women (all sexual practices) | 953 (61) | 966 (61) | 562 (49) | |||
| Heterosexual men | 410 (26) | 409 (26) | 422 (37) | |||
| Homosexual/bisexual men | 5 (0.3) | 6 (0.4) | 21 (1.8) | |||
| Unknown | 200 (13) | 209 (13) | 141 (12) | |||
| Ct diagnosed ever | <0.001 | <0.001 | <0.001 | |||
| No | 1327 (85) | 1485 (93) | 999 (87) | |||
| Yes | 11 (0.7) | 31 (1.9) | 46 (4.0) | |||
| Unknown | 230 (15) | 74 (4.7) | 101 (8.8) | |||
| STI diagnosed ever§ | <0.001 | <0.001 | <0.001 | |||
| No | 1316 (84) | 1469 (92) | 975 (85) | |||
| Yes | 42 (2.7) | 64 (4.0) | 79 (6.9) | |||
| Unknown | 210 (13) | 57 (3.6) | 92 (8.0) | |||
| Age at first time sex | <0.001 | <0.001 | <0.001 | |||
| <18 | 479 (31) | 578 (36) | 482 (42) | |||
| 18 and above | 568 (36) | 563 (35) | 394 (34) | |||
| Unknown | 521 (33) | 449 (28) | 270 (24) | |||
| Number of recent sexual partners¶ | <0.001 | 0.007 | 0.4 | |||
| 0–1 | 1221 (78) | 1143 (72) | 826 (72) | |||
| 2 and more | 78 (5.0) | 72 (4.5) | 68 (5.9) | |||
| Unknown | 269 (17) | 375 (24) | 252 (22) | |||
| Regular partner** | – | 0.14 | – | |||
| No | n.c. | 456 (29) | 387 (34) | |||
| Yes | n.c. | 1091 (69) | 717 (63) | |||
| Unknown | n.c. | 43 (2.7) | 42 (3.7) | |||
| Condom use last sexual contact** | – | <0.001 | – | |||
| No | n.c. | 848 (53) | 640 (56) | |||
| Yes | n.c. | 236 (15) | 261 (23) | |||
| Unknown | n.c. | 506 (32) | 245 (21) | |||
| Condom use regular partner**†† | – | 0.017 | – | |||
| Always | n.c. | 179 (11) | 149 (13) | |||
| Sometimes | n.c. | 69 (4.3) | 45 (3.9) | |||
| Never | n.c. | 734 (46) | 532 (46) | |||
| Unknown | n.c. | 608 (38) | 420 (37) | |||
| Condom use with casual partner**†† | – | <0.001 | – | |||
| Always | n.c. | 68 (4.3) | 141 (12) | |||
| Sometimes | n.c. | 12 (0.8) | 25 (2.2) | |||
| Never | n.c. | 40 (2.5) | 90 (7.9) | |||
| Unknown | n.c. | 1470 (92) | 890 (78) |
P values are based on χ² test. Participants 40–59 years old were excluded (n=844).
An extra category was created for missing data. Missing data are shown as ‘unknown’. Missing data are a mix of ‘I don't know’, ‘I don't want to say’ and not filled in.
*Migration background was based on the country of birth of the participant and both parents and categorised as Dutch, Western non-Dutch (West European countries, Australia, North America, Indonesia and Japan), Morocco and Turkey, SAN and non-Western (other countries).
†Education was classified as theoretical (higher professional education, university-level education) or practical (all other educations).
‡1996: based on sex of sexual partners in the past year; 2007: based on sex of sexual partners in the past 6 months; 2017: based on sex of sexual partners lifetime.
§1996: chlamydia, hepatitis B, gonorrhoea, herpes, genital warts (HPV), syphilis; 2007 and 2017: chlamydia, hepatitis B, gonorrhoea, herpes, genital warts (HPV), syphilis, HIV.
¶1996: number of partners in the past year; 2007 and 2017: number of partners in the past 6 months.
**Data not collected in 1996.
††2007: with partners in the past year and 2017: with partners in the past 6 months.
Ct, Chlamydia trachomatis; HIV, human immunodeficiency virus; HPV, human papillomavirus; n.c., not collected; SAN, Suriname, Aruba and the former Dutch Antilles; STI, sexually transmitted infection.