The impact of a universal human papilloma virus (HPV) vaccination program on lower genital tract dysplasia and genital warts.

Abstract

Assess Ontario's school-based human papillomavirus (HPV) vaccination program on reducing rates of cervical dysplasia, colposcopy services and treatment for genital warts, cervical conization, cryotherapy and laser vaporization of the lower genital tract. Women born in 1995 in Ontario, Canada were the first cohort of students to receive the vaccine. We followed these women from age 18-23 and identified pap test cytology results, referral and attendance at colposcopy, treatment of HPV related warts and treatment of lower-genital tract dysplasia using administrative databases. We compared the incidence of these outcomes to women born in 1985, followed during the same age period prior to access to the HPV vaccine. We calculated relative risk ratios for all outcomes over the 5-year period for the unvaccinated group compared to the vaccinated group. Results were stratified at the income and geographic level. A total of 221,039 women were included. Among vaccinated women, 5.2% percent had cytologic abnormalities and 2.7% required treatment for pre-invasive disease or warts compared to 9.2% and 5.2%, respectively among unvaccinated women. The relative risk of developing a low-grade cytologic abnormality if unvaccinated was 1.69 and 3.74 for high-grade abnormalities. The relative risk of requiring colposcopy if unvaccinated was 1.94 and they were 6.15 times more likely to require treatment. There were no differences between socio-economic groups and geographic regions. Vaccination programs are effective at decreasing rates of cervical dysplasia, lead to reduced need for colposcopy, treatment of HPV related warts and pre-invasive disease even at early ages.