The age distribution of type-specific high-risk human papillomavirus incidence in two population-based screening...

Age- and type-specific high-risk human papillomavirus (hrHPV) incidence estimates in screen-eligible women are relevant from a public health perspective because they provide an indication of the effect of vaccination on the occurrence of screen-positives in HPV-based screening. However, limited data from women over 25 years of age are available.

In 24,105 hrHPV-negative women participating in Dutch (Population-Based Screening Study Amsterdam: POBASCAM) and Italian (New Technologies for Cervical Cancer: NTCC) population-based randomized controlled screening trials the age- and type-specific distribution of incident hrHPV infections detected at the next screening round was assessed. HPV types were grouped into vaccine (bivalent: HPV16/18; polyvalent HPV16/18/31/33/45/52/58) and nonvaccine types.

The incidence of screen-detected hrHPV among women ages 29 to 56 years was 2.54% (95% confidence interval, 2.30-2.78) in POBASCAM and 2.77% (2.36-3.19) in NTCC. In both studies, the incidence of bivalent, polyvalent, and nonpolyvalent infections decreased with age (P < 0.0001). Among women with incident infection(s), vaccine-type positivity changed quadratically with age, in particular for the polyvalent vaccine (P values: POBASCAM: bivalent 0.264, polyvalent 0.038; NTCC bivalent 0.039, polyvalent 0.005). However, more than 20% and 50% of women with incident hrHPV were positive for bivalent and polyvalent vaccine types, respectively, in all ages in both studies.

We observed decreasing age trends of hrHPV vaccine and nonvaccine type incidences and age-related differences in the vaccine-type positivity among women with incident infections. Most importantly, hrHPV infections continued to be detected in all ages and the contribution of vaccine types remained substantial.

Our results indicate a considerable reduction of new hrHPV infections in vaccinated cohorts, ensuing revision of screening guidelines.