Identifying measures for understanding and addressing county-level disparities in adolescent HPV vaccination coverage in North Carolina

Abstract

Background: Human papillomavirus (HPV) vaccination coverage is characterized by geographic disparities in the United States, with national studies finding lower coverage in rural versus nonrural areas. To direct quality improvement efforts in North Carolina, we sought to understand how different rurality measures characterize these disparities. Methods: We used separate negative binomial regression models to test associations between five dichotomized county-level rurality measures and HPV vaccination coverage (>= 1 dose) among North Carolina adolescents, aged 11 to 12 years (n = 326,345). Rurality measures were derived from: Office of Management and Budget's Metropolitan Statistical Areas, Rural-Urban Continuum Codes, Index of Relative Rurality, US Census Bureau classifications, and North Carolina Rural Center classifications. Models controlled for Social Vulnerability Index (SVI) percentile and rate of pediatricians per county. Vaccination data came from the North Carolina Immunization Registry. Results: HPV vaccination coverage was 29% across North Carolina's 100 counties (range: 13%, 46%). Agreement between rurality measures ranged from 54% to 93% of counties. In adjusted analyses, none of the five rurality measures were correlated with HPV vaccination coverage, but higher SVI and higher rate of pediatricians were positively associated with coverage (P < 0.01). Exploratory moderation analyses suggested regional variation in the relationship between rurality and coverage, with a positive association in one region, a negative association in one region, and no association in four regions. Conclusions: County-level rurality measures did not identify disparities in HPV vaccination coverage in North Carolina. Impact: Measures related to social vulnerability and access to pediatricians may be better suited for understanding and addressing the state's substantial county-level vaccination disparities.