The combined impact of implementing HPV immunisation and primary HPV screening in New Zealand: Transitional and long-term benefits, costs and resource utilisation implications.

BACKGROUND: In response to emergent evidence, many countries are transitioning from cytology-based to HPV screening. We evaluated the impact of an upcoming transition on health outcomes and resource utilisation in New Zealand. METHODS: An extensively validated model of HPV transmission, vaccination, natural history and cervical screening ('Policy1-Cervix') was utilised to simulate a transition from three-yearly cytology for women 20-69 years to five-yearly HPV screening with 16/18 genotyping for women 25-69 years, accounting for population growth and the impact of HPV immunisation. Cervical cancer rates, resources use (test volumes), costs, and test positivity rates from 2015 to 2035 were estimated. FINDINGS: By 2035, the transition to HPV screening will result in declines in cervical cancer incidence and mortality rates by 32% and 25%, respectively, compared to 2018. A potentially detectable 5% increase in cervical cancer incidence due to earlier detection is predicted for the year of transition. Annual numbers of women screened will fluctuate with the five-year screening interval. Cytology volumes will reduce by over 80% but colposcopy volumes will be similar to pre-transition rates, and program costs will be reduced by 16%. A 9% HPV test positivity rate is expected in the first round of HPV screening (2019-2023), with 2.7% of women referred for colposcopy. Transitioning from cytology to primary HPV cervical screening could avert 149 cancer cases and 45 deaths by 2035. CONCLUSION: Primary HPV screening and vaccination will reduce cervical cancer and resources use. A small transient apparent increase of invasive cancer rates due to earlier detection may be detectable at the population level, reflecting the introduction of a more sensitive screening test. These findings can be used to inform health services planning and public communications surrounding program implementation.

Impact of human papillomavirus vaccination on rates of abnormal cervical cytology and histology in young New Zealand women.

AIM: Determine the impact of quadrivalent human papillomavirus (HPV) vaccination on abnormal cervical cytology and histology rates in young New Zealand women. METHODS: Retrospective population-based cohort study of women born 1990-1994, with a cervical cytology or histology recorded when aged 20-24 between 1 January 2010 and 31 December 2015. Data was obtained through linking the National Immunisation Register and National Cervical Screening Programme Register. RESULTS: N=104,313 women (376,402 person years of follow up) were included. The incidence of high-grade cytology was lower in vaccinated women (at least one dose prior to 18 years) than in unvaccinated women (8.5 vs 11.3 per 1,000 person years [p1000py], incidence rate ratio [IRR 0.75], 95% CI 0.70, 0.80, p<.001). The incidence of high-grade histology was lower in vaccinated women than in unvaccinated women (6.0 vs 8.7 p1000py, IRR 0.69, 95% CI 0.64, 0.75, p<.001). There was no evidence of a difference in the incidence of high-grade histology between European and Maori women overall or after taking vaccination status into account. CONCLUSIONS: Receiving at least one dose of quadrivalent HPV vaccine prior to 18 years was associated with a 25% lower incidence of high-grade cytology and 31% lower incidence of high-grade histology in women aged 20-24 years.