A prospective study of age trends of high-risk human papillomavirus infection in rural China

Background: In China, high-risk human papillomavirus (HR-HPV)prevalenceisunexpectedlyhigh in older women, but the possible reasons have not been well studied yet. This study investigated the age trends of HR-HPV infection in a prospective study. Methods: A total of 7397 women aged 25-65 years without cervical precancer or cancer were evaluated during 2010-2011 with a stratified sample of 2791 women re-evaluated after one year. Test results for careHPV and careHPV16/18/45 were used to describe the HR-HPV prevalence, incidence and clearance. Risk factors associated with HR-HPV infections were explored using a logistic regression model. Results: The overall HR-HPV prevalence was 13.1% at baseline, with a peak of 19.3% in women aged 55-59 years. The prevalence of HR-HPV (p for trends < 0.001),HPV16/18/45 (p for trends = 0.002), and HR-HPV other than HPV16/ 18/45 (p for trends = 0.002) generally increased with increasing age. Number of infections that cleared was generally greater than number of incident infections within age groups. One-year clearance rate decreased with increasing age (p for trends < 0.001), however, incidence rate was unrelated to age (p for trends = 0.159). Risk factors that associated with HR-HPV infection differed between younger and older women. Conclusions: The greater HR-HPV prevalence in older versus younger women in rural China may be explained by a cohort effect, higher than expected incidence, and/ or poorer clearance at older age.