Systematic identification and replication of factors associated with human papillomavirus vaccine initiation among adolescents in the United States using an environment-wide association study approach.

OBJECTIVE

Human papillomavirus (HPV) vaccination coverage is low among adolescents in the USA. Identification of factors associated with HPV vaccine initiation (receipt of ≥1 dose) is critical for improving uptake. Our objective was to systematically investigate all eligible factors available in a nationally representative sample of adolescents to identify drivers of HPV vaccine initiation using a novel methodological approach.

METHODS

We performed multiple cross-sectional analyses using data from the adolescent component of the National Immunization Surveys (NIS)-Teen between 2014 and 2019. Study participants were parents or caregivers of adolescents aged 13-17 years. Exposure variables measured sociodemographic and geographical characteristics, health conditions and healthcare provision. We tested the association between each factor and HPV vaccine initiation using univariate logistic regression and multivariate logistic regression adjusted for mother's age, mother's education level, mother's marital status, poverty status and adolescent's sex. We validated findings for each type of analysis within surveys, between surveys (across years 2014-2019) and across several subgroups (age, sex, poverty status and race/ethnicity).

RESULTS

Six factors were replicated in the multivariate analysis. Most replicated factors characterised the role of healthcare providers and healthcare-seeking behaviours. After adjustment, provider HPV recommendation remained the most strongly associated with HPV vaccine initiation (2019 NIS-Teen: OR 13.4, 95% CI 11.3 to 17.3, p<0.001). The variance explained by a full model including replicated factors was 0.39.

CONCLUSIONS

This is the first study to explore the association between all available factors in the NIS-Teen and HPV vaccine initiation in a systematic manner. Our study suggests that healthcare-seeking behaviours and interactions with the health system may be drivers of HPV vaccine initiation and warrant further study. Addressing these factors could improve the rate of HPV vaccine initiation among adolescents in the USA.