Abstract
Introduction:
Most genital and oropharyngeal cancers associated with the human papillomavirus (HPV) are preventable through vaccination. Adolescent series completion rates, however, are at 75.8%. Two doses of HPV vaccine are recommended for adolescents, but factors influencing 2-dose series completion are not well explored. The purpose of this study is to examine individual-level and community-level factors associated with timely HPV vaccine series completion (e.g., within 14 months) among adolescents in the Southeastern U.S.
Methods:
A retrospective chart review with a cohort design was used to assess series completion from January 2018 to February 2019 among adolescents initiating the vaccine in 2017. Multivariable logistic regression analysis was conducted to identify individual-level and community-level factors influencing overall series completion and timely series completion.
Results:
Among the sample, 64.4% completed the series of HPV vaccines and 53.8% completed within 14 months. Higher odds of series completion were among adolescents younger at vaccine initiation (AOR=1.94, 95% CI=1.50, 2.50), traveling moderate distances to the clinic (AOR=1.62, 95% CI=1.03, 2.56), and living in low-deprivation neighborhoods (AOR=1.85, 95% CI=1.31, 2.60), and lower among Hispanic (AOR=0.62, 95% CI=0.45, 0.87) and non-Hispanic Black (AOR=0.66, 95% CI=0.54, 0.81) adolescents and those without private insurance (AOR=0.68, 95% CI=0.56, 0.83). Timely series completion resulted in similar findings; however, lower odds were noted among Hispanic (AOR=0.63, 95% CI=0.43, 0.95) and non-Hispanic Black adolescents (AOR=0.68, 95% CI=0.50, 0.92) compared with non-Hispanic other adolescents.
Conclusions:
Individual-level and community-level factors continue to influence series completion among adolescents, despite a reduction in doses. Future research is needed to understand racial/ethnic and regional disparities in HPV vaccine series completion and develop interventions to promote series completion.
INTRODUCTION
Since the introduction of human papillomavirus (HPV) vaccines in 2006, health initiatives have prioritized vaccination among adolescents before sexual debut to prevent HPV and its associated cancers.1–3 HPV infections continue to account for 79% of cervical, vaginal, vulvar, anal, penile, and oropharyngeal cancers.4 HPV vaccination is routinely administered at age 11 and 12 years.5 As of 2016, a total of 2 doses are recommended for vaccine completion (administered 6–12 months apart) if series initiation occurs before age 15 years.5 Despite the reduction from 3 doses to 2 doses for series completion for younger adolescents, HPV vaccination rates remain below the nation’s goal of 80% coverage by age 15 years.2 Initiation rates are at 71.5% among adolescents, with series completion rates (the percentage of adolescents who initiated and completed all recommended doses), at 75.8%.6 More than half of adolescents engaged in sexual intercourse by age 18 years.7 Thus, targeting vaccine series completion during adolescence is critical to mitigate adolescents’ risk of acquiring HPV.
Existing literature on HPV vaccine series completion is largely informed by the 3-dose regimen, with few studies assessing 2-dose series completion. Higher odds of series completion were noted among adolescents who initiated HPV vaccines by age 9–12 years.8–14 Timely series completion with the 2-dose and 3-dose regimen, however, declined over time with rates continually low at 18 months.15 This finding may have implications for adolescents completing the 2-dose series. Racial differences in series completion also exist, with Black and Hispanic adolescents being less likely to complete the series of HPV vaccines.10–12,14,16–18 The influence of insurance and SES on series completion reported mixed findings. Inconsistencies were reported in the odds of series completion among adolescents who were privately insured versus publicly insured.10,13,18,19 Similarly for poverty status, living below the federal poverty level was reported as both a barrier and facilitator to series completion.16,17 Regional differences in series completion rates exist, with rates lower among adolescents living in the U.S. South and Western regions.13,15 The influence of neighborhood characteristics on series completion, however, has not been well explored. Although individual-level and community-level factors influencing HPV vaccine series completion have been examined, most studies do not account for multilevel factors that may impact series completion.
Inconsistencies in findings may be attributable to the interaction between individual and environmental factors influencing HPV vaccine series completion among adolescents. Socioecological models may provide understanding of how factors influence series completion across various levels. The socioecological framework20 posits that individual-level (e.g., biological and personal attributes) and community-level factors (e.g., environmental conditions) interplay with one another to influence individual behavior20 and may have implications for adolescent series completion.
The purpose of this study is to examine individual-level and community-level factors associated with timely 2-dose series completion among adolescents (aged 11–14 years) at a university healthcare system. Specifically, this study examines whether adolescents’ age at vaccination, sex, race/ethnicity, insurance type, neighborhood deprivation, and distance to the clinic are associated with HPV vaccine series completion.
METHODS
A retrospective chart review with a cohort design was used to assess timely series completion (defined as series completion within 14 months) among younger adolescents who received their first HPV vaccine dose. Previous research indicated that the likelihood of series completion among adolescents decreased as time exceeded the recommended clinical practice guidelines of vaccine completion within 12 months of the initial dose.15 Investigators established an observation period of 14 months for series completion to consider possible appointment scheduling delays. A waiver of informed consent was granted to access and review adolescents’ charts retrospectively. IRB approval was obtained from Duke University Health System.
Study Sample
Population-based sampling was used to extract eligible charts from clinics serving adolescents within a university healthcare system. These clinics provide care to >25,000 pediatric patients across various regions in the Southeastern U.S., with roughly 60,000 patient visits annually.21 Clinic types included family medicine, school-based wellness centers, and pediatrics. Eligibility criteria included adolescents aged 11–14 years who received their first HPV vaccine dose between January 2017 and December 2017. A cohort of vaccinated adolescents was created by including all charts that met the inclusion criteria. All adolescents in the cohort were followed from January 2018 to February 2019 to assess timely series completion; however, 324 adolescents completed the series 15–25 months after receiving their first dose.
Measures
Two HPV vaccine series completion outcomes were examined: (1) overall series completion, defined as receiving recommended doses during the January 2017 to February 2019 observation period; and (2) timely series completion, defined as receiving 2 or 3 doses within 14 months from the first dose. Two doses are recommended for series completion if adolescents initiated the series before age 15 years, administered 6–12 months apart.5 Three doses are recommended if the second dose is received <5 months from the first dose or if adolescents are immunocompromised.5 Series completion is recommended within 6–12 months.5 Dates of administration for each vaccine dose were assessed by the first author, a registered nurse with clinical expertise in childhood immunizations, to determine the number of recommended doses for series completion. Both series completion outcomes were assessed by type of visit at the first dose, coded as non–well child visit (0) and well-child visit (1). Well-child visits included wellness visits and annual exams.
Individual-level factors included age at the first dose, sex, race/ethnicity, and insurance type. Age at the first dose was recorded in years. Sex was determined by self-report of female or male in the adolescent’s chart. Race/ethnicity was collapsed into 4 categories: Hispanic, non-Hispanic Black, non-Hispanic White, and non-Hispanic other. Insurance type was created using the insurance provider listed at each visit and grouped into 3 categories: no insurance, private, and public. Self-pay and Medicaid-pending were combined in the “no insurance” category. The authors collapsed insurance type into a private insurance variable coded as no (0) or yes (1) for the regression analysis. The “yes” category included private insurance plans. The “no” category included no insurance and government/public insurance plans.
Community-level factors included neighborhood deprivation and distance to clinic. Using the U.S. Area Deprivation Index data set, 9-digit ZIP codes associated with the adolescent’s home address were used to determine neighborhood deprivation.22 This data set used the Census Block Group, the closest unit of analysis to the neighborhood level, to apply deprivation scores to 9-digit ZIP codes.23 Area deprivation was based upon 17 U.S. Census variables: level of education, median family income, employment, income disparity, housing value and ownership, federal poverty level, single-parent households, and household characteristics.22
Deprivation index values were manually entered for each adolescent’s address. State-level values ranged from 1 to 10 and national-level values ranged from 1 to 100.22 Higher values reflected high deprivation. National-level percentiles were constructed by combining block groups based on 1% range of the Area Deprivation Index.23 State-level index values included deciles and provided rankings for each state.23 State-level and national-level deprivation values were highly correlated (r =0.98). Therefore, state-level deprivation values were used for the regression analysis and grouped into 5 categories: 1–2, 3–4, 5–6, 7–8, and 9–10.
Google Maps was used to calculate distance to clinic. Investigators manually entered each adolescent’s home address at each encounter and the clinic address where HPV vaccine doses were received. The shortest distance in miles was recorded. Distance was assessed during 12:00pm and 3:00pm based on the assumption that evening traffic began between 4:00pm and 5:00 pm and would influence the shortest route selected (e.g., longer routes to avoid traffic). Similar procedures were used in other studies.24,25 Distance to clinic was non-normally distributed and thus combined into 3 categories (0–15 miles, 16–30 miles, and 31–45 miles) based on the assumption that 15-mile intervals presented increasing challenges for HPV vaccine access.
Statistical Analysis
Non-directional statistical tests were conducted with significance set at 0.05. All statistical tests were conducted using SAS, version 9.4.26 Chi-square tests were conducted to examine the association between both series completion outcomes and: (1) type of visit at the first vaccine dose and (2) each individual-level and community-level factor at the first dose for the bivariate analysis (Appendix Table 1). A multivariable logistic regression model was conducted to examine the influence of individual-level and community-level factors on both series completion outcomes. AORs and their 95% CIs were reported to address effect size.
The primary focus was timely series completion. A sample size of 300 was required to achieve 80% power for the multivariable logistic regression model, assuming: (1) statistical significance set at 0.05 for each 2-tailed test; (2) 6 predictors; (3) minimum of 50 adolescents per predictor; and (4) medium effects, indicated by an AOR of 2.47 or inverse AOR of 0.40. The sample of 3,044 adolescents provided 80% power for all planned analyses.
RESULTS
Characteristics of the cohort of vaccinated adolescents are presented in Table 1. Most adolescents initiated HPV vaccines at age 11 years (38.0%) and during well-child visits (85.7%). Nearly half were female (49.0%) and non-Hispanic White (50.2%), followed by 33.7% non-Hispanic Black and 7.5% Hispanic. Most adolescents were privately insured at each visit (64.0%, 70.0%, and 79.0%, respectively), traveled 0–15 miles to the clinic (63.1%), and lived in low-deprivation neighborhoods with state-level deprivation values ranked 1–2 (44.8%).
Table 1.
Sample Characteristics
| Visit 1 (N=3,044) | Visit 2 (N=2,001) | Visit 3 (N=48) | |
|---|---|---|---|
| Demographics | n/N (%) | n/N (%) | n/N (%) |
| Age at first dose, years | |||
| 11 | 1,161/3,044 (38.0) | – | – |
| 12 | 927/3,044 (30.5) | – | – |
| 13 | 535/3,044 (17.6) | – | – |
| 14 | 421/3,044 (13.8) | – | – |
| Sex | |||
| Female | 1,492/3,044 (49.0) | ||
| Male | 1,552/3,044 (51.0) | ||
| Race/Ethnicity | |||
| Hispanic | 215/2,868 (7.5) | – | – |
| Non-Hispanic White | 1,441/2,868 (50.2) | – | – |
| Non-Hispanic Black | 965/2,868 (33.7) | – | – |
| Non-Hispanic Asian | 118/2,868 (4.1) | – | – |
| Non-Hispanic multiracial | 82/2,868 (2.9) | – | – |
| Non-Hispanic other | 47/2,868 (1.6) | – | – |
| Insurance | |||
| No insurance | 15/3,044 (0.5) | 4/2,001 (0.2) | 0/48 (0.0) |
| Private | 1,945/3,044 (64.4) | 1,396/2,001 (69.8) | 38/48 (79.2) |
| Public | 1,084/3,044 (35.6) | 601/2,001 (30.0) | 10/48 (20.8) |
| State-level deprivation index valuea | |||
| 1–2 | 1,317/2,938 (44.8) | – | – |
| 3–4 | 731/2,938 (24.9) | – | – |
| 5–6 | 412/2,938 (14.0) | – | – |
| 7–8 | 272/2,938 (9.3) | – | – |
| 9–10 | 206/2,938 (7.0) | – | – |
| Distance to clinic | |||
| 0–15 miles | 1,866/2,957 (63.1) | – | – |
| 16–30 miles | 994/2,957 (33.6) | – | – |
| 31–45 miles | 97/2,957 (3.3) | – | – |
| Well-child visit | |||
| Non-well child visit | 416/2,917 (14.3) | 512/1,821 (28.1) | 30/41 (73.2) |
| Well-child visit | 2,501/2,917 (85.7) | 1,309/1,821 (71.9) | 11/41 (26.8) |
Notes: N = Subjects with data available for the analysis.
State-level values ranged from 1‒10. Lower values represent low area deprivation; higher values represent high area deprivation. Visit 3=43 adolescents recommended 3 doses and completed 3 doses; however, 5 adolescents who were recommended 2 doses received 3 doses, resulting in N=48 visits.
A total of 3,044 adolescents received a first dose, 2,001 received a second dose, and 48 received a third dose. Table 2 depicts series completion rates by recommended dose. Among vaccinated adolescents, 64.4% completed the series and 53.8% completed within 14 months. Among 3,044 adolescents, 2,961 (97.3%) were recommended 2 doses and 83 (2.7%) were recommended 3 doses for series completion. Five adolescents who were recommended 2 doses received 3 doses. Among adolescents recommended 2 doses, 64.8% completed the series during the observation period and 54.0% completed within 14 months. The lowest rates of series completion (51.8%) and timely series completion (47.0%) were among adolescents recommended 3 doses.
Table 2.
HPV Vaccine Series Completion Rate by Recommended Dose
| Completed recommended dose | Timely completion of recommended dose | |||
|---|---|---|---|---|
| Group | n/N | % | n/N | % |
| All patients | 1,961/3,044 | 64.4% | 1,637/3,044 | 53.8% |
| Recommended 2 dosesa | 1,918/2,961 | 64.8% | 1,598/2,961 | 54.0% |
| Recommended 3 doses | 43/83 | 51.8% | 39/83 | 47.0% |
Notes: Timely completion of recommended dose indicates the adolescent completed recommended vaccine doses within 14-months. N=Subjects with data available for the analysis.
Includes 5 adolescents who were recommended 2 doses but received 3 doses.
HPV, human papillomavirus.
Among 1,961 adolescents completing the series of HPV vaccines during the observation period, the median time to completion was 12 months (range=5–25 months) (Table 3). Among 1,918 adolescents recommended 2 doses, the median time to series completion from the first and second dose was 12 months (range=6–25 months). For 43 adolescents recommended 2 doses, the median time to series completion from Dose 1 to Dose 3 was 7 months (range=5–17 months).
Table 3.
Time to Series Completion Among Completers by Recommended Dose
| Subgroup | Timely series completion n/N (%) | Time to series completion in months Median (25th, 75th) |
|---|---|---|
| All completers | 1,637/1,961 (83.5) | 12.0 (10.0, 13.0) |
| Recommended 2 dosesa | 1,598/1,918 (83.3) | 12.0 (11.0, 14.0) |
| Recommended 3 doses | 39/43 (90.7) | 7.0 (6.0, 12.0) |
Notes: Timely series completion indicates the adolescent completed recommended vaccine doses within 14-months. N=Subjects with data available for the analysis.
Includes 5 adolescents who were recommended 2 doses but received 3 doses. The time to completion reported for the second dose.
Adolescents had a significantly greater likelihood of series completion if the first dose was administered at a well-child visit compared with a non–well child visit (x2=4.01, df=1, p=0.05) (not shown). The overall series completion rate was 65.0% for a well-child visit compared with 60.1% for a non–well child visit.
Table 4 presents the multivariable logistic regression results for overall series completion and timely series completion. The odds of series completion was higher among adolescents who: (1) were younger at vaccine initiation compared with being older (AOR=1.94, p<0.001), (2) traveled moderate distances to the clinic (e.g., 16–30 miles) compared with longer (e.g., 31–45 miles; AOR=1.62, p<0.05) and shorter distances (e.g., 0–15 miles; AOR=1/0.76=1.32, p<0.01), and (3) lived in low-deprivation neighborhoods with state-level deprivation values ranked 1–2 compared with higher values ranked 5–6 (AOR=1.95) and 9–10 (AOR=1.85) (p<0.001).
Table 4.
Multivariable Logistic Regression: Individual and Community-Level Factors at First Dose and Series Completion (N=2,751)
| Overall series completion | Timely series completion | |
|---|---|---|
| Explanatory variables | AOR (95% CI) | AOR (95% CI) |
| Age at first dose, years | ||
| Age 11 vs 12 | 1.58 (1.28, 1.90) *** | 1.47 (1.22, 1.79) *** |
| Age 11 vs 13 | 1.63 (1.29, 2.07) *** | 1.49 (1.19, 1.87) *** |
| Age 11 vs 14 | 1.94 (1.50, 2.50) *** | 1.67 (1.30, 2.12) *** |
| Race/Ethnicity | ||
| Hispanic vs NH Black/AA | 0.95 (0.69, 1.30) | 0.94 (0.68, 1.29) |
| Hispanic vs NH White | 0.62(0.45, 0.87) *** | 0.57 (0.41, 0.80) *** |
| Hispanic vs NH other | 0.71 (0.48, 1.07) | 0.63 (0.43, 0.95) * |
| NH Black/AA vs NH White | 0.66 (0.54, 0.81) *** | 0.61 (0.50, 0.74) *** |
| NH Black/AA vs NH other | 0.76 (0.55, 1.04) | 0.68 (0.50, 0.92) * |
| NH White vs NH other | 1.15 (0.85, 1.56) | 1.10 (0.83, 1.47) |
| Sex | ||
| Female vs Male | 1.12 (0.95, 1.32) | 1.08 (0.92, 1.26) |
| Insurance | ||
| No private vs Private | 0.68 (0.56, 0.83) *** | 0.63 (0.52, 0.76) *** |
| Distance to clinic | ||
| 0–15 miles vs 16–30 miles | 0.76 (0.63, 0.91) ** | 0.84 (0.71, 1.00) * |
| 0–15 miles vs 31–45 miles | 1.22 (0.79, 1.91) | 1.31 (0.84, 2.04) |
| 16–30 miles vs 31–45 miles | 1.62 (1.03, 2.56) * | 1.56 (0.99, 2.45) |
| State-level deprivation valuea | ||
| 1–2 vs 3–4 | 1.12 (0.90, 1.38) | 1.16 (0.95, 1.42) |
| 1–2 vs 5–6 | 1.95 (1.51, 2.52) *** | 1.80 (1.40, 2.31) *** |
| 1–2 vs 7–8 | 1.31 (0.97, 1.78) | 1.32 (0.98, 1.78) |
| 1–2 vs 9–10 | 1.85 (1.31, 2.60) *** | 1.81 (1.28, 2.57) *** |
| 3–4 vs 5–6 | 1.74 (1.34, 2.27) *** | 1.55 (1.19, 2.01) *** |
| 3–4 vs 7–8 | 1.17 (0.86, 1.60) | 1.14 (0.84, 1.54) |
| 3–4 vs 9–10 | 1.65 (1.17, 2.33) ** | 1.56 (1.10, 2.21) * |
| 5–6 vs 7–8 | 0.67 (0.48, 0.94) * | 0.73 (0.53, 1.02) |
| 5–6 vs 9–10 | 0.95 (0.66, 1.36) | 1.01 (0.69, 1.47) |
| 7–8 vs 9–10 | 1.41 (0.95, 2.08) | 1.37 (0.92, 2.05) |
Notes: Timely series completion indicates the adolescent completed recommended vaccine doses within 14-months. N=Subjects with data available for the analysis. Boldface indicates statistical significance (*p<0.05; **p<0.01; ***p<0.001).
Area deprivation index value reported at the state-level. Low values represent low area deprivation; higher values represent high area deprivation.
NH, non-Hispanic.
The odds of series completion, however, were lower among those living in neighborhoods with deprivation values of 5–6 compared with those living in neighborhoods with values of 7–8 (AOR=0.67, p<0.05). Lower odds of series completion were also noted among those without private insurance compared with those with private insurance (AOR=0.68, p<0.001), and among Hispanic (AOR=0.62) and non-Hispanic Black (AOR=0.66) adolescents compared with non-Hispanic White adolescents (p<0.001).
Similar results were noted for timely series completion, with the odds being higher among adolescents who were younger at vaccine initiation, non-Hispanic White, had private insurance, traveled moderate distance to the clinic (e.g., 16–30 miles), and lived in low-deprivation neighborhoods. Lower odds of timely series completion, however, were noted among Hispanic (AOR=0.63) and non-Hispanic Black (AOR=0.68) adolescents compared with non-Hispanic other adolescents (p<0.05).
DISCUSSION
This study examined individual-level and community-level factors associated with timely HPV vaccine series completion among younger adolescents at a university healthcare system. Most adolescents were recommended 2 doses for series completion, reflecting the 2016 vaccine completion guideline change for younger adolescents.5 Overall, series completion rates were lower than the national percentage of 75.8% in 2019.6 Adolescents who initiated HPV vaccines at younger ages, traveled moderate distances to the clinic, and lived in low-deprivation neighborhoods had higher odds of series completion and timely series completion. Series completion and timely series completion was less likely among Hispanic and non-Hispanic Black adolescents and adolescents without private insurance. This study reveals that individual-level and community-level factors continue to influence HPV vaccination, highlighting factors specifically influencing 2-dose series completion.
No significant differences in series completion were noted by sex. This finding shed light on the impact that HPV messaging has on improving vaccination in adolescent boys. Vaccination marketing efforts have included boys and healthcare provider discussions about vaccination have focused on cancer prevention more broadly.27 In 2018, increases in HPV vaccination rates were largely from vaccinating adolescent boys.28 Thus, it appears that parents perceive a benefit to vaccinating their sons.
Although this study and others reported higher odds of series completion when adolescents initiated HPV vaccines at younger ages,8–14 the present findings differed regarding timely series completion. Younger age at vaccine initiation also increased the odds of timely series completion. Other studies, however, reported that younger initiators had lower odds of timely series completion and vaccine adherence,9,13,29 with timely completion declining over time.15 Despite this finding, the present study’s low series completion rates may be explained by adolescents completing the series beyond 14 months, as noted in these studies. Clinicians should clearly discuss the recommended HPV vaccination schedule for series completion and proactively schedule follow-up appointments during clinic visits.
Findings related to racial differences in series completion and timely series completion, namely among Hispanic and non-Hispanic Black adolescents, are consistent to findings reported in other studies.10–12,14,16–18 Non-Hispanic other adolescents, however, were also less likely to complete the series of HPV vaccines.30,31 Differences in findings may be explained by this study’s small sample size in the “other” race/ethnicity group. Concerns about returning for multiple clinic visits for vaccine doses, costs, and transportation were reported barriers to series completion among Black and Hispanic parents.32,33 Additional qualitative research is needed to understand how barriers influence series completion among Black and Hispanic adolescents.
Adolescents having public insurance or no insurance had lower odds of series completion and timely series completion compared with adolescents with private insurance. Other studies reported mixed findings noting both higher and lower odds of series completion among those publicly insured compared with privately insured.11,18 Differences in findings may be explained by the large sample of privately insured adolescents. Preventive health services, including administration of all Advisory Committee on Immunization Practices–recommended vaccines, are covered by private and public health insurance plans without cost sharing for patients through the Affordable Care Act.34
There was a significant association between distance to clinic and series completion. The influence of clinic distance on series completion has not been well explored; however, 1 study noted no association between clinic proximity and vaccine initiation.24 Differences in findings may be explained by the comparison study using the nearest clinic to the adolescent’s home, which may not reflect where the adolescent typically received care,24 whereas this study used the clinic where vaccine doses were received.
Adolescents traveling moderate distances to the clinic had higher odds of series completion and timely series completion compared to adolescents traveling shorter and greater distances. These parents may experience greater challenges to rescheduling appointments because of traveling time to the clinic and may be more motivated to have their children complete the series of HPV vaccines to avoid frequent clinic visits. Adolescents traveling longer distances may lack access to quality health care, especially in rural locations where resources are limited. This finding underscores the importance of increasing access to HPV vaccination among adolescents traveling far distances for care. Future research should consider designing interventions to increase HPV vaccine access at local pharmacies or within mobile clinics to improve series completion among adolescents in hard-to-reach locations.
Adolescents living in low-deprivation neighborhoods had higher odds of series completion and timely series completion compared with adolescents living in moderate- or high-deprivation neighborhoods. The influence of neighborhood characteristics on series completion have not been well explored, although regional differences in series completion were noted.13,15 The extent of how regional characteristics influence series completion is not well understood. Adolescents living in high-deprivation neighborhoods may experience greater challenges to access care due to available community resources. Future research should explore barriers to series completion among adolescents living in high-deprivation areas to inform interventions aimed at improving series completion rates.
Limitations
This study has several limitations. Using clinic electronic health record data limited the ability to capture vaccine doses administered outside of the university healthcare system and may bias the study’s findings. Electronic health record data were collected retrospectively from 1 healthcare system containing clinics largely located within metropolitan areas. Therefore, the generalizability of the study findings is limited to clinics in other locations and rural areas, and inferences on causality cannot be drawn from this analysis. Proxy variables selected as individual-level and community-level factors from the electronic health record were limited by definition and availability, limiting the ability to explore differences among gender minority youth and identifying other factors influencing series completion, such as provider recommendation. The Area Deprivation Index data set was limited in identifying rurality and specific geographic characteristics influencing series completion. Lastly, the selected distance may not reflect the actual route traveled by adolescents and does not account for travel time, public transportation, and traffic.
CONCLUSIONS
Although fewer doses are recommended for HPV vaccine completion for younger adolescents, barriers continue to influence series completion. Future research is needed to understand racial/ethnic and regional disparities in series completion. Innovative interventions are needed to improve access to HPV vaccines in hard-to-reach areas. Lastly, implementing standardized patient–provider communication for vaccine completion and care coordination for subsequent doses may improve adolescent series completion rates.
ACKNOWLEDGMENTS
Research reported in this publication was supported by the National Institute of Nursing Research of NIH under Award Number F31NR018347. The content is solely the responsibility of the authors and does not necessarily represent the official views of NIH.
Dr. Lisa Mansfield wrote the paper, conducted the research study and data analysis, and revised the paper. Dr. Susan Silva served as the statistician on the research study assisting with data analysis and providing substantive editing to the Methods and Results section. Dr. Elizabeth Merwin provided feedback on drafts and revisions of the final paper. Dr. Richard Chung provided content expertise on adolescent health and the selected healthcare system and provided feedback on the final paper. Dr. Gonzalez-Guarda served as the senior author and provided guidance on the conceptualization of the paper and methods used, feedback on drafts, and final editing of the paper. No financial disclosures or conflict of interests were reported by the authors of this paper.
Appendix Table 1. Bivariate Analysis: Individual and Community-Level Factors at First Dose and Series Completion
| Non-completers (N=1,083) |
Completers (N=1,961) |
||
|---|---|---|---|
| Explanatory variable | n/N (%) | n/N (%) | p-value |
|
| |||
| Age at first dose, years | <0.0001 | ||
| 11 | 361/1,083 (33.3) | 800/1,961 (40.8) | |
| 12 | 351/1,083 (32.4) | 576/1,961 (29.4) | |
| 13 | 193/1,083 (17.8) | 342/1,961 (17.4) | |
| 14 | 178/1,083 (16.4) | 243/1,961 (12.4) | |
| Sex | 0.2307 | ||
| Female | 515/1,083 (47.6) | 977/1,961 (49.8) | |
| Male | 568/1,083 (52.4) | 984/1,961 (50.2) | |
| Race/Ethnicity | <0.0001 | ||
| Hispanic | 105/1,024 (10.3) | 110/1,844 (6.0) | |
| Non-Hispanic Black | 431/1,024 (42.1) | 534/1,844 (29.0) | |
| Non-Hispanic White | 409/1,024 (39.9) | 1,032/1,844 (56.0) | |
| Non-Hispanic other | 79/1,024 (7.7) | 168/1,844 (9.1) | |
| Insurance | <0.0001 | ||
| No private | 511/1,083 (47.2) | 588/1,961 (30.0) | |
| Private | 572/1,083 (52.8) | 1,373/1,961 (70.0) | |
| Distance to clinic | <0.0001 | ||
| 0–15 miles | 709/1,039 (68.2) | 1,157/1,918 (60.3) | |
| 16–30 miles | 287/1,039 (27.6) | 707/1,918 (36.9) | |
| 31–45 miles | 43/1,039 (4.1) | 54/1,918 (2.8) | |
| State-level deprivation index valuea | <0.0001 | ||
| 1–2 | 368/1,036 (35.5) | 949/1,902 (49.9) | |
| 3–4 | 246/1,036 (23.8) | 485/1,902 (25.5) | |
| 5–6 | 199/1,036 (19.2) | 213/1,902 (11.2) | |
| 7–8 | 117/1,036 (11.3) | 155/1,902 (8.1) | |
| 9–10 | 106/1,036 (10.2) | 100/1,902 (5.3) | |
Notes: N=Subjects with data available for the analysis. Chi-square analysis conducted.
State-level deprivation index value. Low values represent low area deprivation; higher values represent high area deprivation.
REFERENCES
- 1.HPV Vaccination for Cancer Prevention: Progress, Opportunities, and a Renewed Call to Action. A Report to the President of the United States from the Chair of the President’s Cancer Panel. Bethesda, MD: President’s Cancer Panel; 2018. [Google Scholar]
- 2.Immunization and infectious diseases. HHS. https://www.healthypeople.gov/2020/topics-objectives/topic/immunization-and-infectious-diseases/objectives. Updated October 8, 2020. Accessed October 15, 2020. [Google Scholar]
- 3.HPV vaccination information for health professionals. American Cancer Society. https://www.cancer.org/health-care-professionals/hpv-vaccination-information-for-health-professionals/our-hpv-vaccination-initatives.html. Accessed October 15, 2020. [Google Scholar]
- 4.HPV and cancer. Centers for Disease Control and Prevention. http://www.cdc.gov/cancer/hpv/statistics/cases.htm. Updated September 3, 2020. Accessed October 15, 2020. [Google Scholar]
- 5.Meites E, Kempe A, Markowitz LE. Use of a 2-dose schedule for human papillomavirus vaccination: updated recommendations of the Advisory Committee on Immunization Practices. MMWR Morb Mortal Wkly Rep. 2016;65(49):1405–1408. 10.15585/mmwr.mm6549a5. [DOI] [PubMed] [Google Scholar]
- 6.Elam-Evans LD, Yankey D, Singleton JA, et al. National, regional, state, and selected local area vaccination coverage among adolescents aged 13–17 years — United States, 2019. MMWR Morb Mortal Wkly Rep. 2020;69(33):1109–1116. 10.15585/mmwr.mm6933a1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Abma JC, Martinez GM. Sexual activity and contraceptive use among teenagers in the United States, 2011‒2015. Natl Health Stat Report. 2017;(104):1–23. [PubMed] [Google Scholar]
- 8.St Sauver JL, Rutten LJF, Ebbert JO, et al. Younger age at initiation of the human papillomavirus (HPV) vaccination series is associated with higher rates of on-time completion. Prev Med. 2016;89:327–333. 10.1016/j.ypmed.2016.02.039. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Hirth JM, Tan A, Wilkinson GS, et al. Completion of the human papillomavirus vaccine series among insured females between 2006 and 2009. Cancer. 2012;118(22):5623–5629. 10.1002/cncr.27598. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Inguva S, Barnard M, Ward LM, et al. Factors influencing human papillomavirus (HPV) vaccination series completion in Mississippi Medicaid. Vaccine. 2020;38(8):2051–2057. 10.1016/j.vaccine.2019.12.030. [DOI] [PubMed] [Google Scholar]
- 11.Schluterman NH, Terplan M, Lydecker AD, et al. Human papillomavirus (HPV) vaccine uptake and completion at an urban hospital. Vaccine. 2011;29(21):3767–3772. 10.1016/j.vaccine.2011.03.032. [DOI] [PubMed] [Google Scholar]
- 12.Ackerson B, Hechter R, Sidell M, et al. Human papillomavirus vaccine series completion in boys before and after recommendation for routine immunization. Vaccine. 2017;35(6):897–902. 10.1016/j.vaccine.2017.01.007. [DOI] [PubMed] [Google Scholar]
- 13.Liu G, Kong L, Du P. HPV vaccine completion and dose adherence among commercially insured females aged 9 through 26 years in the US. Papillomavirus Res. 2016;2:1–8. 10.1016/j.pvr.2015.10.001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Freeman AJH, Gamboa C, Darbinian JA, et al. Disparities in human papillomavirus vaccine completion rates among females in an integrated health care system. Obstet Gynecol. 2018;132(3):717–723. 10.1097/aog.0000000000002802. [DOI] [PubMed] [Google Scholar]
- 15.Spencer JC, Brewer NT, Traogdon JG, et al. Predictors of human papillomavirus vaccine follow-through among privately insured US patients. Am J Public Health. 2018;108(7):946–950. 10.2105/ajph.2018.304408. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Dorell CG, Yankey D, Santibanez TA, et al. Human papillomavirus vaccination series initiation and completion, 2008‒2009. Pediatrics. 2011;128(5):830–839. 10.1542/peds.2011-0950. [DOI] [PubMed] [Google Scholar]
- 17.Niccolai LM, Mehta NR, Hadler JL. Racial/Ethnic and poverty disparities in human papillomavirus vaccination completion. Am J Prev Med. 2011;41(4):428–433. 10.1016/j.amepre.2011.06.032. [DOI] [PubMed] [Google Scholar]
- 18.Agawu A, Hanlon AL, Buttenheim AM, et al. Disparities in human papillomavirus vaccine series completion by adolescent males: a retrospective cohort study. Acad Pediatr. 2020;20(3):364–373. 10.1016/j.acap.2019.05.002. [DOI] [PubMed] [Google Scholar]
- 19.Reiter PL, Gupta K, Brewer NT, et al. Provider-verified HPV vaccine coverage among a national sample of Hispanic adolescent females. Cancer Epidemiol Biomarkers Prev. 2014;23(5):742–754. 10.1158/1055-9965.epi-13-0979. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.The social-ecological model: A framework for prevention. Center for Disease Control and Prevention. https://www.cdc.gov/violenceprevention/about/social-ecologicalmodel.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fviolenceprevention%2Fpublichealthissue%2Fsocial-ecologicalmodel.html. Updated January 28, 2020. Accessed October 15, 2020. [Google Scholar]
- 21.Duke Health Performance Services. Clinic data provided by Duke Health performance services. https://ps.duhs.duke.edu/performance-services-home. Accessed March 3, 2021.
- 22.Kind AJ, Jencks S, Brock J, et al. Neighborhood socioeconomic disadvantage and 30-day rehospitalization: a retrospective cohort study. Ann Intern Med. 2014;161(11):765–774. 10.7326/m13-2946. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.2015 Area Deprivation Index v2.0. University of Wisconsin School of Medicine and Public Health. https://www.neighborhoodatlas.medicine.wisc.edu/. Accessed October 15, 2020. [Google Scholar]
- 24.Tsui J, Singhal R, Rodriguez HP, et al. Proximity to safety-net clinics and HPV vaccine uptake among low-income, ethnic minority girls. Vaccine. 2013;31(16):2028–2034. 10.1016/j.vaccine.2013.02.046. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Mabeya H, Menon S, Weyers S, et al. Uptake of three doses of HPV vaccine by primary school girls in Eldoret, Kenya: a prospective cohort study in a malaria endemic setting. BMC Cancer. 2018;18:557. 10.1186/s12885-018-4382-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.SAS Institute Inc. 2015. SAS/IML® 9.4 User’s Guide. Cary, NC: SAS Institute Inc. [Google Scholar]
- 27.Gilkey MB, Calo WA, Moss JL, et al. Provider communication and HPV vaccination: the impact of recommendation quality. Vaccine. 2016;34(9):1187–1192. 10.1016/j.vaccine.2016.01.023. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Walker TY, Elam-Evans LD, Yankey D, et al. National, regional, state, and selected local area vaccination coverage among adolescents aged 13–17 years — United States, 2018. MMWR Morb Mortal Wkly Rep. 2019;68(33):718–723. 10.15585/mmwr.mm6833a2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Rahman M, Hirth JM, Berenson AB. Adherence to ACIP recommendation for human papillomavirus vaccine among US adolescent girls. J Community Health. 2017;42(2):385–389. 10.1007/s10900-016-0267-6. [DOI] [PubMed] [Google Scholar]
- 30.Monnat SM, Rhubart DC, Wallington SF. Differences in human papillomavirus vaccination among adolescent girls in metropolitan versus non-metropolitan areas: considering the moderating roles of maternal socioeconomic status and health care access. Matern Child Health J. 2016;20(2):315–325. 10.1007/s10995-015-1831-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Chuang E, Cabrera C, Mak S, et al. Primary care team- and clinic level factors affecting HPV vaccine uptake. Vaccine. 2017;35(35 Pt B):4540–4547. 10.1016/j.vaccine.2017.07.028. [DOI] [PubMed] [Google Scholar]
- 32.Roncancio AM, Ward KK, Carmack CC, et al. Hispanic mothers’ beliefs regarding HPV vaccine series completion in their adolescent daughters. Health Educ Res. 2017;32(1):96–106. 10.1093/her/cyw055. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 33.Katz IT, Bogart LM, Fu CM, et al. Barriers to HPV immunization among Blacks and Latinos: a qualitative analysis of caregivers, adolescents, and providers. BMC Public Health. 2016;16:874. 10.1186/s12889-016-3529-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Gates A, Ranji U, Snyder L. Coverage of preventive services for adults in Medicaid. https://www.kff.org/medicaid/issue-brief/coverage-of-preventive-services-for-adults-in-medicaid/view/print/. Published November 13, 2014. Accessed October 15, 2020.