Table 2.

OR and 95% CI of CIS in relation to HPV-16 and smoking habits

VariableCases/controlsCrude OR (95% CI)Adjusted OR* (95% CI)
HPV-16 status
    Negative268/346ReferenceReference
    Positive107/178.4 (4.9-14.5)8.4 (4.8-14.7)
HPV-16 load
    Negative268/346ReferenceReference
    Low31/85.1 (2.3-11.3)5.5 (2.4-12.6)
    High76/911.4 (5.6-23.4)11.0 (5.3-22.6)
    Ptrend (Wald)P < 0.0001
HPV-16 proportion/persistence
    Negative94/181ReferenceReference
    Low8/180.8 (0.3-2.0)0.8 (0.3-2.0)
    High154/2512.2 (7.4-19.9)11.8 (7.2-19.5)
Smoking status
    Nonsmokers131/181ReferenceReference
    Current smokers244/1821.9 (1.4-2.6)1.7 (1.2-2.4)
Age at smoking debut (y)
    Never110/162ReferenceReference
    ≥16162/1281.9 (1.3-2.6)1.8 (1.2-2.5)
    <16103/732.2 (1.4-3.2)1.7 (1.1-2.6)
Smoking duration (y)
    0119/171ReferenceReference
    <561/561.5 (1.0-2.4)1.5 (0.9-2.4)
    ≥5195/1362.1 (1.5-2.9)1.7 (1.2-2.4)
Smoking intensity (pack-years)
    0119/171ReferenceReference
    <2.5116/881.9 (1.3-2.8)1.7 (1.2-2.6)
    ≥2.5140/1041.9 (1.4-2.7)1.6 (1.1-2.3)
  • * ORs are adjusted for age at first smear, number of years between date of smear and diagnosis, current oral contraceptive use, and parity as categorized in Table 1. Smoking-associated variables were adjusted for HPV-16 status (negative, positive) and HPV-16-associated variables were adjusted for current smoking status (nonsmoker, current). Number of sex partners before first smear was included as a continuous variable.

  • Categories for HPV-16 proportion: 0, <0.5, ≥0.5.

  • Current smokers, subject smoked within 2 years before the smear date; nonsmokers, subject never smoked or smoked >2 years before the smear date.