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Declining rates of cervical intraepithelial neoplasia in British Columbia, Canada: An ecological analysis on the effects of the school‐based human papillomavirus vaccination program
Author(s) -
Donken Robine,
Niekerk Dirk,
Hamm Jeremy,
Spinelli John J.,
Smith Laurie,
Sadarangani Manish,
Albert Arianne,
Money Deborah,
Dobson Simon,
Miller Dianne,
Lee Marette,
MitchellFoster Sheona,
Krajden Mel,
Naus Monika,
Ogilvie Gina
Publication year - 2021
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.33513
Subject(s) - cervical intraepithelial neoplasia , medicine , vaccination , demography , cervix , cervical cancer , population , incidence (geometry) , gynecology , rate ratio , cohort , obstetrics , cancer , immunology , environmental health , physics , sociology , optics
Since 2008, girls in British Columbia (BC), Canada, have been offered HPV vaccination through a school‐based, publicly funded immunization program. The oldest birth cohort eligible for the vaccination program was born in 1994 and uptake is on average 63%. To evaluate the impact of the HPV vaccine in BC, ecological trends in cervical intraepithelial neoplasia (CIN) rates were assessed in young women before and after the implementation of the HPV vaccination program. Information on all Pap smears and histopathological abnormalities, in calendar years 2004‐2017 in women 16‐28 years of age in BC were obtained from the population‐based BC Cancer Cervix Screening Program database. Rates of CIN 2 and 3 were calculated as the number of cases divided by the number of cytology specimens for that period. Rate ratios (RR) were calculated by negative binomial piecewise regression. Age‐centered incidence rates of CIN 2 and 3 in BC declined significantly among women 16‐23 years of age after HPV vaccine introduction compared to before vaccine introduction. The overall reduction postvaccination for CIN2 and 3 in women 16‐23 years was respectively 62% (95% CI 54‐68%) and 65% (95% CI 58‐71%). Age‐specific rates for CIN2 significantly declined for those 18‐22 years of age and for those 19, 20 and 23 years of age for CIN3. Among women 24‐28 years of age no decline in CIN2 and 3 rate over time was observed. The observed reduction in CIN 2 and 3 rates since the introduction of the school‐based HPV vaccine program might illustrate the population impact of the BC provincial school‐based HPV vaccination program.