Factors Predicting Completion of the Human Papillomavirus Vaccine Series

PurposeThis study identified factors associated with completion of the three dose quadrivalent human papillomavirus vaccine (HPV4) series by female adolescents.MethodsBetween February and September 2008, we prospectively surveyed 11- to 26-year-old female members of an integrated managed care organization shortly after their first HPV4 dose to identify factors that predicted series completion. We used regression analyses to assess whether self-reported experiences at the index visit, knowledge/attitudes about HPV and HPV4, and medical record data on adverse events, demographic characteristics, care-utilization frequency, and visit characteristics, were associated with vaccine series completion within one year of the first HPV4 dose.ResultsOf 899 survey respondents (27% of 3347 survey recipients), 786 (87%) maintained continuous enrollment in the health plan in the year following the first HPV4 dose. Fifty percent (n = 393) completed the vaccine series within that year. In multivariate analyses of survey respondents, only respondents’ ability to correctly identify the number of shots required for series completion was significantly associated with series completion. Reported bruising was associated with decreased likelihood of completion, and the clinician stating that future shots were required was associated with increased likelihood, but both were of borderline significance. Females ages 16–20 had the lowest series completion.ConclusionsImproving HPV4 completion will require targeted efforts. Our results suggest that providers may help by stressing the need for additional doses of vaccine, and confirming that patients understand this information. Special attention should be given to females ages 16–20. Future randomized trials should assess the effect on vaccine completion of these simple, low-cost interventions.