Opportunistic HPV vaccination at age 16–23 and cervical screening attendance in Sweden: a national register-based cohort study

OBJECTIVES: To investigate whether cervical screening attendance differs between human papillomavirus (HPV)-vaccinated and unvaccinated women and to investigate potential underlying socioeconomic factors. DESIGN: Prospective cohort using registry linkage of vaccinations, screening invitations, screening attendance and socioeconomic covariates. SETTING: Swedish national HPV vaccination and cervical screening programmes. PARTICIPANTS: All Swedish women born between 1988 and 1991 and invited to screening (n=261 434). OUTCOME MEASURES: All participants were followed for up to 3 years. Screening attendance was compared between HPV-vaccinated and unvaccinated women. HR and 95% CI were estimated using Cox regression. RESULTS: Vaccination age averaged 18.1 years and the coverage for≥1 dose was 13.5%. In HPV-vaccinated women (n=35 460), screening attendance was higher than in unvaccinated women (n=225 974) (74%vs69%, p<0.001). The crude HR of attendance in HPV-vaccinated women was 1.32 (95% CI 1.30 to 1.34). A positive association remained after adjustment for education, income and migration history (HR=1.10, 95% CI 1.09 to 1.12). CONCLUSION: HPV-vaccinated women were more likely to attend screening than unvaccinated women. Yet, the question needs to be reassessed in routinely vaccinated cohorts, since the vaccinated women included here represent a selected group and may be prone to more health-conscious habits.