Table 2. Baseline characteristics of women in pooled analysis, based on active or passive smoking status.
| Characteristics | Active smoking | Passive smoking | |||||
|---|---|---|---|---|---|---|---|
| Never smoker | Ever smoker | p-value | No | Yes | p-value | ||
| No. of subjects | 16,112 | 310 | 4,321 | 12,101 | |||
| Age (yr) | 0.103 | <0.001 | |||||
| 17–35 | 5,089 (31.6) | 84 (27.1) | 1,477 (34.2) | 3,696 (30.5) | |||
| 36–49 | 9,359 (58.1) | 185 (59.7) | 2,328 (53.9) | 7,216 (59.6) | |||
| ≥50 | 1,664 (10.3) | 41 (13.2) | 516 (11.9) | 1,189 (9.8) | |||
| Geographic area | <0.001 | <0.001 | |||||
| Rural | 12,851 (79.8) | 163 (52.6) | 2,923 (67.7) | 10,091 (83.4) | |||
| Urban | 3,261 (20.2) | 147 (47.4) | 1,398 (32.3) | 2,010 (16.6) | |||
| Education level | 0.006 | <0.001 | |||||
| Illiterate and primary school | 6,766 (42.0) | 106 (34.2) | 1,565 (36.2) | 5,307 (43.9) | |||
| Middle school and above | 9,346 (58.0) | 204 (65.8) | 2,756 (63.8) | 6,794 (56.1) | |||
| Age at menarche | 0.426 | <0.001 | |||||
| ≤15 | 9,095 (56.4) | 182 (58.7) | 2,575 (59.6) | 6,702 (55.4) | |||
| ≥16 | 7,017 (43.6) | 128 (41.3) | 1,746 (40.4) | 5,399 (44.6) | |||
| Age at sexual debut | 0.003 | <0.001 | |||||
| ≤20 | 7,681 (47.7) | 174 (56.1) | 1,819 (42.1) | 6,036 (49.9) | |||
| ≥21 | 8,431 (52.3) | 136 (43.9) | 2,502 (57.9) | 6,065 (50.1) | |||
| Menopause* | 0.014 | 0.006 | |||||
| Yes | 1,650 (10.3) | 45 (14.6) | 494 (11.5) | 1,201 (10.0) | |||
| No | 14,414 (89.7) | 264 (85.4) | 3,818 (88.5) | 10,860 (90.0) | |||
| Lifetime No. of sexual partners* | <0.001 | 0.026 | |||||
| 1 | 13,734 (85.3) | 187 (60.3) | 3,709 (85.9) | 10,212 (84.4) | |||
| ≥2 | 2,370 (14.7) | 123 (39.7) | 611 (14.1) | 1,882 (15.6) | |||
| Parity* | <0.001 | <0.001 | |||||
| 0 | 385 (2.4) | 23 (7.6) | 137 (3.3) | 271 (2.3) | |||
| 1−2 | 10,700 (67.6) | 201 (66.6) | 2,930 (70.2) | 7,971 (66.6) | |||
| ≥3 | 4,754 (30.0) | 78 (25.8) | 1,106 (26.5) | 3,726 (31.1) | |||
| Contraceptive use* | |||||||
| Oral contraceptives | 500 (3.1) | 29 (9.4) | <0.001 | 185 (4.3) | 344 (2.8) | <0.001 | |
| Condoms | 1,873 (11.6) | 67 (21.6) | <0.001 | 824 (19.1) | 1,116 (9.2) | <0.001 | |
| IUD | 3,921 (24.3) | 100 (32.3) | 0.001 | 1,195 (27.7) | 2,826 (23.4) | <0.001 | |
| Sterilization | 10,092 (62.6) | 150 (48.4) | <0.001 | 2,265 (52.4) | 7,977 (65.9) | <0.001 | |
| Husband's extramarital affair | <0.001 | 0.462 | |||||
| Yes | 1,344 (8.3) | 80 (25.8) | 363 (8.4) | 1,061 (8.8) | |||
| No | 14,768 (91.7) | 230 (74.2) | 3,958 (91.6) | 11,040 (91.2) | |||
| HPV positive | 2,321 (14.4) | 71 (22.7) | <0.001 | 585 (13.5) | 1,807 (14.9) | 0.026 | |
| CIN2+* | 366 (2.4) | 15 (5.1) | 0.003 | 99 (2.4) | 282 (2.4) | 0.854 | |
| Passive smoking | <0.001 | ||||||
| Yes | 11,842 (73.5) | 259 (83.5) | |||||
| No | 4,270 (26.5) | 51 (16.5) | |||||
Values are presented as number of subjects (%).
CIN2+, cervical intraepithelial neoplasia grade 2 or worse; HPV, human papillomavirus; IUD, intrauterine device.
*Smaller sample size than categorical groups due to missing values.