Age factor and implication of human papillomavirus type-specific prevalence in women with normal cervical cytology

The prevalence and genotype distribution of human papillomavirus (HPV) infection in women with normal cervical cytology varies widely according to the population studied. Two non-overlapping population-based cohort studies of women aged >= 30 years for the periods 2008-2009 (n = 5026) and 2004-2005 (n = 10 014) were analysed. The prevalence rate of HPV was 11.0% (95% CI 10.5-11.6). HPV infection was significantly associated with age, menopausal status, and inversely associated with hormone replacement therapy. There was an increasing trend of alpha 3/alpha 15, alpha 5/alpha 6, and multiple HPV infections with increasing age. The five most common types were HPV52, 18, 53, 58 and 70, while HPV16, 31, 33 ranked 21st, 25th, and 16th, respectively, in the merged cohort with normal cytology (n = 14 724). HPV16, 31, and 33 were significantly associated with abnormal cytology, which could have resulted in their rarity in the total merged cohort (n = 15 040).