Evaluating the Population Impact of HPV Vaccine on High Grade Cervical Intraepithelial Neoplasia Rates in an Era of Decreasing Screening
Methods: Screening rates and CIN2+ incidence rates from 2008-2012 were calculated for females aged 18-29, in Monroe County, New York. Screening data were obtained from three local laboratories that collectively process all Monroe County PAP smear test specimens. Cases of CIN2+ were ascertained according to the HPV-IMPACT protocol from all pathology laboratories serving Monroe County residents. The 2010 Census population was used as the denominator for both rates. Poisson regression was used to determine Rate Ratios (RRs) and 95% CIs of CIN2+ cases over 5 years using 2008 as reference year, with and without adjusting for change in screening rates.
Results : From 2008-2012, rates of screening and CIN2+ cases declined by 34.9% and 49%, respectively. The crude RR for screening [0.64 (0.63, 0.65)] and CIN2+ incidence [0.51 (0.44, 0.60,)] indicate declines in 2012 compared to 2008. While adjusting for screening rates somewhat attenuated the RR for CIN2+ incidence, it remained lower in 2012 than in 2008 [0.71 (0.60, 0.84)].
Conclusion: CIN2+ cases and cancer screening rates have both declined since 2008. CIN2+ incidence rates declined independently of screening rates, suggesting that HPV vaccination may have contributed to the reduction of CIN2+ disease incidence.
S. Hariri, None
L. Markowitz, None
E. Van Wijngaarden, None
G. Hollick, None
N. M. Bennett, None