Population-based evaluation of type-specific HPV prevalence among women in British Columbia, Canada

Background: British Columbia (BC) introduced a school-based HPV vaccine program in September 2008. As part of the HPV vaccine program evaluation, we determined the type-specific HPV prevalence in a population-based sample of women presenting for routine cervical cancer screening in the province.

Methods: From June 2010 to February 2011, a total of 1100 physicians from all health regions in BC were invited to return ten sequential cytobrushes used during routine office-based Pap screening to the Provincial Health Services Authority Laboratories for HPV type-specific testing. Client age was the only identifier provided. Specimens were screened by the Digene Hybrid Capture(®) 2 High-Risk (hr) HPV DNA Test (HC2). HC2 positive specimens were then genotyped using the Roche cobas(®) 4800 HPV Test, the Roche Linear Array (LA) HPV Genotyping Test and the Digene(®) HPV Genotyping LQ Test.

Results: Overall, 12.2% of the 4330 specimens with valid HC2 results were hrHPV positive. Age range was 15-69 (median 39.0). By age group, the proportion HC2 hrHPV positive was: 15-19, 25.7%; 20-24, 33.2%; 25-29, 21.9%; 30-34, 12.6%; 35-39, 9.5%; 40-44, 8.4%; ≥45, 3.4%. Overall hrHPV prevalence was 10.1% by Roche cobas(®) 4800, 10.5% by Roche LA and 10.3% by Digene LQ. For HPV 16/18, rates by age group by Roche LA were: 15-19, 5.1%/2.8%; 20-24, 9.5%/3.9%; 25-29, 6.2%/1.0%; 30-34, 2.4%/1.7%; 35-39, 1.2%/1.0%; 40-44, 1.6%/0.2%; ≥45, 0.3%/0.2%. Similar HPV 16/18 rates were obtained with the Digene LQ and Roche cobas(®) 4800 methods. Agreement between the three genotyping methods for HPV 16 and 18 was high.

Conclusions: Comparable to other evaluations, hrHPV positivity was highest among younger women and HPV 16 was the most frequent genotype detected. These baseline estimates will be useful for monitoring the effectiveness of the HPV vaccine in BC. Type-specific analyses repeated at regular intervals over time may determine whether the use of HPV vaccine results in hrHPV genotype replacement in the province.