The HPV Vaccine May Be Underutilized by Certain Subgroups of Insured Youth
A young woman’s likelihood of having been vaccinated against the human papillomavirus (HPV) varies by her age, her racial and ethnic status, and the gender and specialty of her primary care physician, among other characteristics, according to a study of more than 285,000 participants in a managed health care organization.1 Thirty-seven percent of 9–17-year-olds and 16% of 18–26-year-olds had received the first of three HPV vaccination shots between October 2006 and March 2008. Among 9–17-year-olds, initiation of vaccination was positively associated with being Hispanic (relative risk, 1.04) and negatively associated with being black, Asian or a member of another racial or ethnic group (0.9 each). Hispanic ethnicity was negatively associated with vaccination among 18–26-year-olds (0.95), as was membership in any other racial or ethnic group except Asians (0.8–0.95). Analyses restricted to those who had visited a primary care physician, an obstetrician or a gynecologist during the study period were consistent with analyses among the full sample.
Researchers used electronic medical record data from the 179,580 adolescent women (9–17-year-olds) and 105,685 young adult women (18–26-year-olds) who were members of Kaiser Permanente Southern California—the region’s largest managed care organization—between October 2006 and March 2008. Separate multivariable regression anal-yses were conducted to examine whether adolescents’ and young adults’ initiation of the HPV vaccine was associated with their social and demographic characteristics, health care utilization history and health conditions; selected immune-related conditions (included in the study for postmarket surveillance of vaccine safety); and the characteristics of their primary care provider.
Overall, 37% of adolescents and 16% of young adults had received the first of three vaccine shots during the study period. Initiation of vaccination was most common among those aged 13–15. In crude analyses, almost every measure included was associated with initiating the HPV vaccine.
In multivariable analysis among adolescents, 13–14-year-olds and 15–16-year-olds had greater odds than those aged 11–12 of having initiated the HPV vaccine (relative risks, 1.2 and 1.1, respectively); 9–10-year-olds and those aged 17 had reduced odds of vaccination (0.5 and 0.9, respectively). Compared with whites, Hispanics were more likely (1.04), and blacks, Asians and members of other racial and ethnic groups less likely (0.9 each), to have been vaccinated. In addition, vaccination was positively associated with neighborhood income, Medicaid status, number of primary care provider or emergency department visits, influenza vaccination and drug allergies (1.01–1.2); it was negatively associated with neighborhood educational level, having a family practitioner or internist (rather than a pediatrician) as a primary care provider, having a male primary care provider and number of hospitalizations (0.8–0.99).
Among young adults, those who were older than 18 had lower odds than 18-year-olds of having initiated the HPV vaccine (relative risks ranged from 0.8 for 19–20-year-olds to 0.3 for 25–26-year-olds). Hispanics were less likely than whites to have been -vaccinated (0.95), as were blacks and members of other racial and ethnic groups (0.8–0.95), but not Asians. Additionally, vaccination was positively associated with neighborhood educational level and income, having a family practitioner as a primary care provider, number of primary care provider visits, influenza vaccination, history of STDs or Pap tests, and having asthma or allergies (1.02–1.3); vaccination was negatively associated with having an internist (rather than a pediatrician) as a primary care provider, having a male primary care provider, number of hospitalizations or emergency department visits and pregnancy history (0.5–0.97).
Because the HPV vaccine is best given before initiation of sexual activity, the researchers performed a subanalysis among 9–12-year-olds. Overall, the associations with vaccination among these younger adolescents were similar to those among the full adolescent sample; however, there were some exceptions. For example, blacks and Asians aged 9–12 were no less likely than their white peers to have initiated the vaccine, and being Hispanic had a slightly stronger association with vaccination among younger adolescents (relative risk, 1.1) than among adolescents overall.
An additional subanalysis was conducted among adolescents and young women who had visited a primary care physician, an obstetrician or a gynecologist during the study period, to examine the relationship between young women’s HPV vaccination initiation and their opportunity to visit a doctor for another reason. In crude analyses, many of the included social, demographic and health care–related measures were associated with having visited a physician; however, the results of multivariate analyses among the restricted sample were consistent with those among the full sample.
The researchers note several limitations of their study—for example, because racial and ethnic data were missing for approximately 50% of the sample, they imputed the data using a previously validated algorithm. However, they also point out their study’s strengths, such as its population-based design to reduce selection bias and its use of electronic medical records to reduce recall bias. They conclude that their findings "should prove helpful in developing HPV immunization programs in managed care organizations" and, specifically, "education materials…tailored to subgroups underutilizing the vaccine."
1. Chao C et al., Correlates for human -papillomavirus vaccination of adolescent girls and young women in a managed care organization, American Journal of Epidemiology, 2010, 171(3):357–367.