Introducing human papillomavirus (HPV) primary testing in the age of HPV vaccination: projected impact on colposcopy services in Wales.

Objective: To determine the demand for colposcopy in the Cervical Screening Wales programme after the introduction of human papillomavirus (HPV) cervical screening, which coincided with the start of screening of women vaccinated against HPV types 16/18.

Design: The study used a computational model that assigns screening and screening-related colposcopy events to birth cohorts in individual calendar years.

Setting: Cervical Screening Wales.

Population: Women aged 25-64 years from birth cohorts 1953-2007.

Methods And Main Outcome Measures: We estimated the numbers of colposcopies and high-grade cervical intraepithelial lesions (CIN2+) within Cervical Screening Wales in 2018-32, using official population projections for Wales and published estimates of the effects of HPV screening and vaccination.

Results: Vaccination will reduce the number of colposcopies by 10% within the first 3-4 years after the national roll-out of HPV screening, and by about 20% thereafter. The number of screening colposcopies is estimated to increase from 6100 in 2018 and peak at 8000 (+31%) in 2021, assuming current screening intervals are maintained. The numbers of CIN2+ lesions follow similar patterns, stabilising at around 1000 diagnoses per year by 2026, approximately 60% lower than at present. Extending the screening intervals to 5 years for all women shows similar trends but introduces peaks and troughs over the years.

Conclusions: Vaccination will not fully prevent an increase in colposcopies and detected CIN2+ lesions during the first 2-3 years of HPV-based screening but the numbers are expected to decrease substantially after 5-6 years.

Tweetable Abstract: HPV-based cervical screening will initially increase colposcopy referral. In 6 years, this increase will be reversed, partly by HPV vaccination.