Worldwide prevalence and genotype distribution of cervical human papillomavirus DNA in women with normal cytology: a meta-analysis.

We set out to estimate the age and genotype-specific prevalence of cervical human papillomavirus (HPV) DNA in women with normal cervical cytology worldwide by meta-analysis of a systematic literature review. Reports on HPV prevalence published between January, 1995, and January, 2005, were retrieved. To be included, studies required information on cervical cytology, plus detailed descriptions of study populations, methods used to collect cervical samples, and assays used for HPV DNA detection and typing. Final analyses included 78 studies that could be separated into women with normal cytology, and of which subsets of 44 and 48 studies had data on age and type-specific HPV prevalence, respectively. Overall HPV prevalence in 157 879 women with normal cervical cytology was estimated to be 10.4% (95% CI 10.2-10.7). Corresponding estimates by region were Africa 22.1% (20.9-23.4), Central America and Mexico 20.4% (19.3-21.4), northern America 11.3% (10.6-12.1), Europe 8.1% (7.8-8.4), and Asia 8.0% (7.5-8.4). In all world regions, HPV prevalence was highest in women younger than 35 years of age, decreasing in women of older age. In Africa, the Americas, and Europe, a clear second peak of HPV prevalence was observed in women aged 45 years or older. On the basis of these estimates, around 291 million women worldwide are carriers of HPV DNA, of whom 32% are infected with HPV16 or HPV18, or both. The HPV types most commonly detected are similar to those most commonly described in pre-neoplastic and cancer cases, although the relative contribution of HPV16 and HPV18 is substantially lower in cytologically normal women.