Adolescent Human Papillomavirus Vaccine Utilization: Experience of the First Year

Background:
The human papillomavirus (HPV) vaccine series may be difficult to successfully administer to adolescents because it requires 3 doses for completion. Understanding adolescents' HPV vaccine utilization patterns is important for informing future interventions to improve vaccination rates in this age group.

Objectives:
1) To determine the proportion of adolescents initiating and completing the HPV vaccination series within the first year of vaccine availability at a university-based health care system. 2) To determine if there are differences in adolescent HPV vaccine utilization by medical specialty or by patient characteristics.

Methods:
Electronic medical records from 9-18 year old females seen in outpatient pediatric, family medicine or obstetric/gynecology clinics from January 2007-March 2008 at the University of Michigan were reviewed to determine the proportion initiating and completing the HPV vaccination series. Patient and clinic characteristics associated with vaccine receipt were evaluated.

Results:
28% of 10,082 eligible adolescents initiated HPV vaccination - of those, 75% completed the 3-dose series. Among adolescents overall, including those who were eligible for but did not initiate vaccination, series completion was only 15%. A significantly lower proportion of adolescents seen in gynecology clinics (17%) initiated HPV vaccination than in pediatric or family medicine clinics (29% each, p<0.05). Series initiation was significantly more common at preventive care visits (55%) than at problem-focused (28%) or immunization-only (17%, p<0.05) visits. Second and third doses were more commonly administered at “immunization only” visits (75% and 78%, respectively). Series initiation and completion were significantly associated with adolescent race and insurance status, but not with age.

Conclusions:
A high proportion of adolescents initiating the HPV vaccination series complete it. However, in the first year of HPV vaccine availability, series initiation among adolescents overall was low. Observed differences in vaccine utilization by medical specialty and by patient characteristics provide important insight for interventions to improve vaccination rates among adolescents.