Effect of additional adjustment by potential confounding factors on the RR and 95% CI of invasive cervical cancer in relation to lifetime number of sexual partners or age at first intercourse in a subset of 5,383 cases and 9,500 controls who had complete information on all variables
| Adjustment variables | RR (95% CI) | |||
|---|---|---|---|---|
| Lifetime number of sexual partners (≥2 vs 1) | 5-y decrease in age at first intercourse | |||
| Age + study | 2.21 (2.03-2.41) | 2.02 (1.89-2.15) | ||
| Age + study + lifetime number of sexual partners or age at first intercourse | 1.86 (1.65-2.10) | 1.78 (1.66-1.91) | ||
| As above + | ||||
| Number of full-term pregnancies | 1.91 (1.57-2.33) | 1.51 (1.36-1.67) | ||
| Age at first full-term pregnancy | 1.93 (1.59-2.35) | 1.22 (0.95-1.55) | ||
| Education | 2.00 (1.69-2.38) | 1.49 (1.35-1.63) | ||
| Tobacco smoking | 1.72 (1.50-1.98) | 1.73 (1.60-1.87) | ||
| Hormonal contraceptive use | 1.74 (1.53-1.99) | 1.82 (1.69-1.97) | ||
| Condom use | 1.81 (1.59-2.06) | 1.74 (1.62-1.88) | ||
| History of Pap smear | 1.65 (1.41-1.95) | 1.69 (1.55-1.85) | ||
| Number of and age at first full-term pregnancy | 1.75 (1.21-2.53) | 1.18 (0.78-1.78) | ||