Background: We describe changes in rates of cervical intraepithelial neoplasia grades 2, 3 and adenocarcinoma in situ (CIN2+) during a period of human papillomavirus (HPV) vaccine uptake and changing cervical cancer screening recommendations.
Methods: We conducted population-based laboratory surveillance for CIN2+ in catchment areas in 5 states, 2008-2015. We calculated age-specific CIN2+ rates per 100000 women by age groups. We estimated incidence rate ratios (IRR) of CIN2+ for 2-year periods among all women and among screened women to evaluate changes over time.
Results: A total of 16572 CIN2+ cases were reported. Among women aged 18-20 and 21-24 years, CIN2+ rates declined in all sites, whereas in women aged 25-29, 30-34, and 35-39 years, trends differed across sites. The percent of women screened annually declined in all sites and age groups. Compared to 2008-2009, rates among screened women were significantly lower for all 3 periods in women aged 18-20 years (2010-2011: IRR 0.82, 95% confidence interval [CI] 0.67-0.99; 2012-2013: IRR 0.63, 95% CI 0.47-0.85; 2014-2015: IRR 0.44, 95% CI 0.28-0.68) and lower for the latter 2 time periods in women aged 21-24 years (2012-2013: IRR 0.86, 95% CI 0.79-0.94; 2014-2015: IRR 0.61, 95% CI 0.55-0.67).
Conclusions: From 2008-2015, both CIN2+ rates and cervical cancer screening declined in women aged 18-24 years. The significant decreases in CIN2+ rates among screened women aged 18-24 years are consistent with a population-level impact of HPV vaccination.
Keywords: cervical intraepithelial neoplasia; disease surveillance; human papillomavirus; vaccine impact.
Published by Oxford University Press for the Infectious Diseases Society of America 2018.