Having private medical insurance was the strongest single predictor of completing the HPV vaccine series. Patients with private insurance had significantly higher vaccination completion rates than patients who had public insurance (odds ratio [OR] 1.87, 95% confidence interval [CI] 1.26–2.76; P=.002; Table 3). This differential was more pronounced in suburban clinics than in urban clinics. In suburban clinics, women with private insurance were substantially more likely to complete vaccination than those with public insurance (37.8% compared with 13.2%, OR 4.02, 95% CI 1.55–10.39; P=.002). In urban clinics, private insurance also was associated with higher HPV4 completion rates than public insurance (30.0% compared with 21.1%, OR 1.61, 95% CI 1.05–2.46; P=.03). Although private insurance patients examined in suburban offices had higher vaccine compliance than those examined in urban offices (37.8% compared with 30.0%, OR 1.42, 95% CI 1.03–1.95; P=.03), those patients with public insurance had similarly low HPV vaccine completion rates for both suburban and urban sites (13.2% compared with 21.1%; P=.26; Fig. 1A).
Among young adults (age 18–26 years), HPV4 completion rates in urban and suburban practices were very similar (31.0% compared with 31.8%; P=.85). However, we found that in girls age 11–17 years, completion rates were very different depending on practice location. In urban practices, female children and adolescents were much less likely than young adults to complete vaccination (22% compared with 31.8%, OR 0.60, 95% CI 0.39–0.93; P=.023; Fig. 1B). Conversely, in suburban practices, female children and adolescents were more likely to complete vaccination than young adults (44.9% compared with 31.0%, OR 1.82, 95% CI 1.39–2.37; P<.001; Fig. 1B). In analyses segregated by practice types, we found that differences in HPV4 completion were also strongly associated with practice location. Pediatric patients seen in suburban practices were more than twice as likely as pediatric patients seen in urban practices to complete vaccination (47.7% compared with 19.7%, OR 2.71, 95% CI 2.51–5.48; P<.001; Fig. 1C). This finding is consistent with the rates of completion analyzed by age cohorts. In gynecology practices, we found no difference in completion rates between suburban and urban clinics (38.2% compared with 36.4%; P=.7). Because 58% of the pediatric patients were examined in urban clinic settings as compared with only 28% of the gynecology patients, overall pediatric HPV4 completion rates were lower than overall gynecology completion rates (31.5% compared with 37.7%, OR 0.76, 95% CI 0.59–0.98; P=.03). These findings suggest that girls and young women examined in urban clinics face significant barriers that hamper their ability to undergo the complete preventive vaccination regimen. This is of concern because they are arguably a cohort at high risk for HPV disease.
Although it is generally appreciated that prophylactic HPV vaccines are underutilized, less is known about specific factors that can be used to predict noncompletion of the three-dose vaccine regimen. Here, we report on vaccine completion rates in a multisite, multipractice academic setting. Similar to other cohort studies,16–19 our cohort had low rates of vaccine completion; only one-third of patients who initiated the series received all three shots within the recommended 12 months. This analysis identifies the combination of young patient age and urban practice location as a predictor of failure to complete three HPV vaccinations in patients who had obtained an initial vaccination.
Only HPV vaccine doses administered at one of four outpatient clinic sites were captured. Any other doses administered by any other provider were not included in the analysis. Whereas this limitation could potentially skew our analysis toward underestimation of vaccine completion rates, our electronic medical record system does include visits to all institution-related practice sites. The likelihood that girls and young women would obtain booster vaccinations with outside providers, without documentation, is low, based on the cost of vaccination. Another potential limitation of our analysis is that all patients were seen in clinics affiliated with a single academic institution. Although this cohort comprises a significant diversity of patients in terms of types of insurance, practice locations, and patient age and race or ethnicity, these findings may not be generalizable to nonacademic practice settings.
In our cohort, overall, patients seen in pediatric practices had lower HPV vaccine completion rates than patients seen in gynecology practices. This finding was unexpected and differs from other reports.20 Providers in pediatrics practices are more accustomed than providers in gynecology practices in counseling and administration of preventive vaccinations. Moreover, pediatric practices have established office infrastructure to track vaccine delivery. Completion rates for other recommended pediatric and adolescent multidose vaccinations, including measles, mumps, and rubella and hepatitis B, are nearly 90% in girls age 13–17 years.16
This unexpectedly low pediatric vaccine completion rate may be attributable to a skewed sociodemographic distribution between urban and suburban practices in our study. Most of the young or pediatric patients in our analysis received their care in urban practice settings. In our cohort, these patients had much lower rates of HPV4 completion than girls and young women receiving care in suburban practice settings. HPV completion rates in our older patient population and among the patients seen in gynecology outpatient clinics did not differ by clinic location. This finding suggests that clinic location is linked to the likelihood of vaccine completion in our younger patients. In contrast, clinic location is not associated with differences in completion in our older patients. Further research is needed to identify the barriers that prevent young patients in the urban setting from completing vaccination. Because most of the financial burden should be alleviated through the Federal Vaccine for Children program, other barriers must still be preventing compliance with the three-shot HPV series in this subpopulation. The disparities in HPV4 compliance in the younger population could be a consequence of several factors, including differences in access to care, in cultural attitudes toward vaccination, or in the ability to provide adequate counseling.
The discussion of preventive HPV vaccination currently is structured around sexual behavior that presents risk, a subject that may be unsettling for some parents and time-consuming for providers. In addition, the current strategy for preventive HPV vaccination is predominantly sex-based. Lessons should be learned from the history of the implementation of the rubella vaccine. Initial sex-based efforts to start vaccinations were spectacularly ineffective, and it was not until rubella prevention was presented in the context of reducing risk of congenital disease to unborn children that it became school-mandated and near-herd immunity was achieved.21 It may be that if prophylactic HPV vaccines were presented as a means to prevent cancer, instead of a means to prevent an infection associated with sexual contact, that uptake would increase.
Finally, the logistic and financial difficulties presented by clinic-based vaccine administration are consistent with the vaccine completion rates in our cohort. The three-shot series requires an office tracking system, a positive attitude about the vaccine by both provider and patient, and three vaccination appointments that are billed as procedures. In other developed high-resource settings in which preventive HPV vaccine administration is school-based, vaccination uptake and completion rates are significantly higher than in the United States. For example, in the United Kingdom, HPV vaccine is administered through a school-based program with an opt-out; vaccine coverage is 80.1%.22 In Australia, which also has instituted a school-based HPV vaccination program, vaccine coverage is 86%.23 Mandatory, school-based vaccination, even with an opt-out, is controversial in the United States.24,25
Studies to date provide evidence that barriers to vaccination include cost, access to health care, cultural beliefs, lack of vaccine awareness, and misperceptions about vaccination.7,26 Studies also indicate that minority women and women receiving care in inner city clinics have low rates of both initiation and completion of the vaccine regimen.18,20,27,28 Our results also support these findings. Additionally, inner city youths were also at significant risk for not completing the HPV4 series. Because these cohorts have low rates of screening and high rates of disease, investigation into the reasons for these disparities deserves focused attention.5,6 Strategies to improve preventive HPV vaccination compliance should target this at-risk population of young urban patients.
Short of a complete overhaul of reimbursement for preventive counseling and approach to vaccine delivery, initiatives to enhance vaccine completion rates in urban pediatric cohorts in the United States could involve communication-based interventions such as text message reminders the day before vaccination appointments. Because this type of intervention is being evaluated as a strategy to enhance compliance with daily oral contraceptive pill use in young women,29 it is conceivable that HPV vaccination could benefit from this approach. Furthermore, developing and instituting an electronic medical record system that can automatically send reminders to a patient or provider whenever a patient has missed the HPV vaccine dose would also help increase compliance. In the end, although survey data in the United States suggest that knowledge30 and acceptability7 of the HPV vaccine is high, we and others report that even among girls and young women who start the vaccination series, rates of completion are surprisingly low. Preventive HPV vaccines are an opportunity to reduce the incidence of HPV-associated disease and costs associated with current primary prevention strategies. Research is needed to identify reasons why persons who start HPV vaccination do not complete the series, and research is needed to develop and evaluate strategies to achieve more successful rates of HPV vaccine completion.
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© 2011 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.
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