Table 3. Association of passive smoking with the risk of CINs and cervical cancer according to smoking habits of study participants.
| Normal | CIN 1 | CIN 2/3 | Cervical cancer | |||||||
| N (%)a | N (%) | Univariable | Multivariable | N (%) | Univariable | Multivariable | N (%) | Univariable | Multivariable | |
| OR (95% CI)b | OR (95% CI)c | OR (95% CI) | OR (95% CI) | OR (95% CI) | OR (95% CI) | |||||
| Non-smokersd | ||||||||||
| Passive smoking | ||||||||||
| No | 345 (65) | 193 (56) | 1 (ref.) | 1 (ref.) | 72 (53) | 1 (ref.) | 1 (ref.) | 80 (62) | 1 (ref.) | 1 (ref.) |
| Yes | 184 (35) | 152 (44) | 1.47 (1.11–1.94) | 1.53 (1.07–2.18) | 64 (47) | 1.67 (1.14–2.45) | 1.52 (0.93–2.48) | 49 (38) | 1.15 (0.77–1.71) | 1.11 (0.54–2.27) |
| Exposure time of passive smoking | ||||||||||
| No | 345 (84) | 193 (65) | 1 (ref.) | 1 (ref.) | 71 (84) | 1 (ref.) | 1 (ref.) | 80 (78) | 1 (ref.) | 1 (ref.) |
| <2 hours/day | 41 (10) | 68 (23) | 3.12 (2.02–4.81) | 2.48 (1.49–4.14) | 7 (8) | 1.33 (0.55–3.18) | 1.32 (0.50–3.52) | 15 (15) | 1.18 (0.49–2.82) | 0.89 (0.18–4.31) |
| ≥2 hours/day | 25 (6) | 37 (12) | 2.58 (1.51–4.41) | 2.28 (1.21–4.26) | 7 (8) | 0.87 (0.37–2.03) | 0.78 (0.30–2.00) | 7 (7) | 1.66 (0.87–3.16) | 0.36 (0.05–2.91) |
| P for linear trend | <0.0001 | 0.0003 | 0.6741 | 0.8162 | 0.286 | 0.5985 | ||||
| Smokers | ||||||||||
| Passive smoking | ||||||||||
| No | 21 (33) | 30 (40) | 1 (ref.) | 1 (ref.) | 12 (41) | 1 (ref.) | 1 (ref.) | 4 (25) | 1 (ref.) | 1 (ref.) |
| Yes | 42 (67) | 45 (60) | 0.77 (0.38–1.55) | 0.62 (0.26–1.49) | 17 (59) | 0.73 (0.29–1.80) | 0.48 (0.14–1.58) | 12 (75) | 1.54 (0.44–5.35) | 0.86 (0.10–7.47) |
| Exposure time of passive smoking | ||||||||||
| No | 21 (53) | 30 (48) | 1 (ref.) | 1 (ref.) | 12 (63) | 1 (ref.) | 1 (ref.) | 4 (36) | 1 (ref.) | 1 (ref.) |
| <2 hours/day | 11 (28) | 21 (33) | 1.34 (0.53–3.35) | 0.90 (0.30–2.73) | 2 (11) | 1.09 (0.29–4.11) | 0.38 (0.06–2.34) | 5 (45) | 1.31 (0.20–8.62) | — |
| ≥2 hours/day | 8 (20) | 12 (19) | 1.05 (0.37–3.01) | 0.48 (0.12–1.88) | 5 (26) | 0.32 (0.06–1.68) | 0.15 (0.01–1.52) | 2 (18) | 2.39 (0.53–10.7) | 2.52 (0.19–33.3) |
| P for linear trend | 0.8045 | 0.3021 | 0.8402 | 0.1894 | 0.5938 | 0.7451 | ||||
CI, confidence interval; CIN, low-grade cervical intraepithelial neoplasia; OR, odds ratio.
Non-smokers indicate women who never smoked for their life but exposed or non-exposed to passive smoking.
aThis number indicates that the number of participants and their percentage.
bMultinomial logistic regression analysis was performed to assess the association between smoking behaviors and the risk of cervical dysplasia (CIN 1, CIN 2/3, and cervical cancer).
cThe multinomial logistic regression analysis was adjusted for age, parity, oral contraceptive use, menopausal status, and oncogenic-HPV infection status.
dNon-smokers indicate women who never smoked for their life but exposed or non-exposed to passive smoking.