title: A prospective study of age trends of high-risk human papillomavirus infection in rural China.
abstract: BACKGROUND
  In China, high-risk human papillomavirus (HR-HPV) prevalence is unexpectedly high 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.
authors.forename: Le-Ni
authors.initials: LN
authors.lastname: Kang
authors.forename: Philip E
authors.initials: PE
authors.lastname: Castle
authors.forename: Fang-Hui
authors.initials: FH
authors.lastname: Zhao
authors.forename: Jose
authors.initials: J
authors.lastname: Jeronimo
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.forename: Pooja
authors.initials: P
authors.lastname: Bansil
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Wen
authors.initials: W
authors.lastname: Chen
authors.forename: Xun
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 17 Panjiayuan Lane, Beijing, 100021, China. qiaoy@cicams.ac.cn.
authors.forename: You-Lin
authors.initials: YL
authors.lastname: Qiao
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D002681:China; D004279:DNA, Viral / Q000032:analysis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D027383:Papillomaviridae; D030361:Papillomavirus Infections / Q000175:diagnosis* / Q000453:epidemiology*; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012424:Rural Population; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis
chemical_list: D004279:DNA, Viral