Cohort characteristics of study endpoints at 18.5 and at 22 years of age
| Categories | At 18.5 years | At 22 years | ||
| SIL (N=940) | No SIL (N=9980) | SIL (N=129) | No SIL (N=6489) | |
| Age at first sexual intercourse | ||||
| 8–13 years | 31 (3.3%) | 316 (3.2%) | 2 (1.5%) | 162 (2.5%) |
| 14–18 years | 712 (75.7%) | 7546 (75.6%) | 85 (65.9%) | 4392 (67.7%) |
| 19–22 years | NA | NA | 13 (10.1%) | 697 (10.7%) |
| Missing | 197 (21.0%) | 2118 (21.2%) | 29 (22.5%) | 1238 (19.1%) |
| New sexual partners last year (n) | ||||
| 2 or less | 546 (58.0%) | 6068 (60.8%) | 61 (47.3%) | 4209 (64.9%) |
| 3 or more | 197 (21.0%) | 1793 (18.0%) | 39 (30.2%) | 1032 (15.9%) |
| Missing | 197 (21.0%) | 2119 (21.2%) | 29 (22.5%) | 1248 (19.2%) |
| Current smoking | ||||
| No | 579 (61.6%) | 5971 (59.8%) | 49 (38.0%) | 3273 (50.4%) |
| Yes | 297 (31.6%) | 3203 (32.1%) | 38 (29.5%) | 1518 (23.4%) |
| Missing | 64 (6.8%) | 806 (8.1%) | 42 (32.5%) | 1698 (26.2%) |
| OC-use | ||||
| No | 152 (16.2%) | 1645 (16.5%) | 14 (10.8%) | 573 (8.8%) |
| Yes | 591 (62.8%) | 6202 (62.1%) | 85 (65.9%) | 4648 (71.6%) |
| Missing | 197 (21.0%) | 2133 (21.4%) | 30 (23.3%) | 1268 (19.6%) |
| Condom use last year | ||||
| Not at all | 182 (19.4%) | 1978 (19.8%) | 32 (24.8%) | 1965 (30.3%) |
| Sometimes | 207 (22.0%) | 2216 (22.2%) | 24 (18.6%) | 1164 (17.9%) |
| In half of the intercourse | 95 (10.1%) | 985 (9.90%) | 12 (9.3%) | 603 (9.3%) |
| Almost always | 135 (14.4%) | 1160 (11.6%) | 21 (16.3%) | 669 (10.3%) |
| Always | 111 (11.8%) | 1433 (14.4%) | 10 (7.7%) | 776 (12.0%) |
| Missing | 210 (22.3%) | 2208 (22.1%) | 30 (23.3%) | 1312 (20.2%) |
| HPV16/18 | ||||
| Negative | 886 (94.3%) | 9500 (95.2%) | 106 (82.2%) | 5307 (81.7%) |
| Positive | 54 (5.70%) | 480 (4.80%) | 2 (1.5%) | 49 (0.8%) |
| Missing* | 21 (16.3%) | 1133 (17.5%) | ||
*Cytological results were missing for 781 of the HPV16/18 results among 18.5 years old.
HPV, human papillomavirus; OC, oral contraceptive; SIL, squamous intraepithelial lesions.