The Longitudinal Incidence of Human Papillomavirus Vaccination in Spanish Primary Care in the First 10 Years After Approval.

BACKGROUND: In Spain, girls are vaccinated against human papillomavirus (HPV) in the primary care setting, according to a national vaccination programme. Vaccination is voluntary and is covered by the public health system.
OBJECTIVES: The aim of the study was to estimate the incidence and patterns of HPV vaccination amongst girls in primary care in Spain.
METHODS: A cohort study was performed using the information recorded in the Spanish Primary Care Database for Pharmacoepidemiological Research (BIFAP) from 7.9 million patients from seven Spanish regions, between 2001 and 2016 (56.6% of the regional population). Data available in BIFAP include patient age, sex, life-style factors, clinical events, specialist referrals, prescriptions, and vaccinations as recorded by the primary care physician (PCP) or administering nurse. The study cohort comprised all girls aged 9-18 years registered in BIFAP between 1st January of 2007 and 31st December of 2016 who had at least 1 year of clinical record information with their PCP (inclusion criteria). The date the inclusion criteria were met was designated as the start date to the study cohort contribution. In order to estimate the incidence of HPV vaccination (initiation of vaccination schedule), girls with an HPV vaccination recorded before the start date or without vaccination date were excluded. Girls forming the study cohort were followed from start date until there was a recorded HPV vaccination, they reached 19 years of age or died, end of available information, or 31st December 2016. The person-time of all patients forming the study cohort was reckoned in the incidence estimations. The follow-up was replicated yearly from 2007 to 2016. The cumulative incidence (CuIn) of vaccination by birth cohort, year and region, was estimated using life tables (proportion of vaccination by intervals in which the denominator is the initial population corrected for losses).
RESULTS: Of 388,690 girls forming the study population, 154,211 initiated the vaccination during 2007-2016. Ages ranged from 12 to 14 years at first dose in 84.5% of vaccinated girls, 42.79% received a quadrivalent vaccine, 21.86% a bivalent vaccine, and 35.35% an unknown type. Of the vaccinated population, 48.0% were completely vaccinated with a three-dose schedule and 28.9% with a two-dose schedule, 20.2% received one dose and 3.0% two doses in a three-dose schedule, at a maximum of 10 years of follow-up. The CuIn was highest among girls aged either 13 or 14 years over all regions (reaching 92.8% and 89.7%, respectively), and aged 12 in some regions/years (up to 89.8%). Girls aged 15 years were also vaccinated (although showing lower yearly incidence, i.e. < 69.1%) in two regions. The coverage was broadened to younger girls (11 years) during the last years of the study period in some regions.
CONCLUSIONS: According to BIFAP primary care data, a high incidence of vaccination among girls aged 13-14 years was observed. Vaccination among younger and older girls were less common, although they reached high incidence in some regions and/or years. Most vaccination patterns adjusted to a complete vaccination regimen, as recommended posology.