Table 2

Risk factors associated with seroconversion of anti-human papillomavirus (HPV)-16 IgG: multivariate time-dependent proportional hazards regression analysis

Adjusted relative risk (95% confidence interval) for seroconversionP
Age at baseline (per year increase)0.82 (0.64–1.06)0.122
User of oral contraceptive pills at time t
 No1
 Yes2.88 (1.28–6.47)0.010
HPV-16 IgA antibodies at time t
 No1
 Yes7.89 (2.54–24.50)<0.001
HPV types detected ≤ time t
 HPV negative or other types1
 HPV-16 or related (31, 33, 35, 52, or 58) viral load
  Low14.27 (3.78–53.91)<0.001
  High37.80 (13.49–105.93)<0.001