Systematic review of HPV vaccine initiation and completion: Surveillance data from national and local studies in the United States

The human papillomavirus (HPV) vaccine will only have an impact on cervical cancer disparities in the United States if the populations who suffer disproportionately from morbidity and mortality (minority, low-income, and medically underserved) use this primary prevention strategy. Several recent descriptive studies have examined HPV vaccine initiation (receipt of 1 dose) and completion (all 3 doses) as well as factors associated with these outcomes in national and local populations. Careful review of these surveillance efforts is critical to understand whether subpopulations most likely to benefit from the vaccine are adopting it, and whether financing and delivery policy initiatives are effective at reaching underserved groups. The aim of this systematic literature review is to provide an overview of the U.S. population subgroups that initiated and completed the HPV vaccine series during its first three years on the market. Medline searches were performed and characteristics of studies including data collection dates, study population, sample size, population subgroup (teen, young adult, mixed), race/ethnicity, data source, and correlates associated with initiation and/or completion were abstracted. Random effects models and meta-regression analyses will be applied to evaluate heterogeneity between studies and identify sources of heterogeneity. We abstracted data from 18 studies published between 2008 and 2010 covering 313,284 participants. All but one study provided initiation estimates (range: 5.0 to 63.5%) and nine reported completion estimates (range: 0.2 and 58.2%). Five studies estimated national rates, while the remaining studies investigated initiation among clinic/managed care populations (n = 10), regional populations (n = 2), and students enrolled in a university (n = 1). Few sociodemographic, health care access, and psychosocial variables were consistently examined across studies. Variables found to be positively associated with initiation in more than one study were: insurance coverage, recommendation by a health care provider, low perceived barriers, and belief that family and friends approve of the vaccine. Pattern of association between initiation and race/ethnicity was mixed; some studies found higher vaccine coverage among Caucasian girls and young women than among their Hispanic and African American counterparts, while other studies reported higher coverage among Hispanics as compared to Caucasians. Published studies suggest that initiation and completion of the HPV vaccine series in its initial years on the market has been limited to moderate. To enable identification of subgroups that might benefit from targeted vaccine promotion, researchers should investigate a consistent set of variables in local populations including race/ethnicity, socioeconomic status, and insurance status.