Genotype-Specific Persistence of Genital Human Papillomavirus (HPV) Infections in Women Followed for 6 Years in the Finnish Family HPV Study

Background. Persistent human papillomavirus (HPV) infection is the most important risk factor for cervical cancer, and understanding genotype-specific HPV persistence is essential for elucidating the natural history of HPV infections. Methods. In the Finnish Family HPV Study, 329 pregnant women (mean age, 25.5 years) were recruited during the third trimester of pregnancy and were followed up for 6 years. Multiplex HPV genotyping for 27 low-and high-risk HPV types was used to define genotype-specific prevalence at each visit. Generalized estimating equation models were constructed to estimate predictors of type-specific persistence (positive results at 2 consecutive visits) of species 7 and 9 HPV genotypes. Results. HPV16 was the most common type, followed by HPV types 18, 31, 35, 45, 58, 70, and 6. Prevalence of multiple infections ranged from 21% to 45%. Persistence was most prolonged for HPV types 35, 58, and 52, with durations of 38.7, 32.1, and 24.2 months, respectively, and was equal for multiple-type infections and HPV16, with durations of 21 and 24 months, respectively. Independent predictors of type-specific persistence of species 7 and 9 HPV genotypes were age (odds ratio, 1.13 [95% confidence interval, 1.02-1.25]; P=.017), oral sex (odds ratio, 0.37 [95% confidence interval, 0.17-0.81]; P=.013), and young age (! 13 years) at initiation of smoking (odds ratio, 0.51 [95% confidence interval, 0.27-0.98]; P=.046). Conclusion. HPV16 was the most frequent persisting HPV genotype followed by multiple infections. Early initiation of smoking, practicing oral sex and older age increase the risk for persistence of species 7 and 9 HPV genotypes.