The Impact of the Human Papillomavirus Vaccine on High-Grade Cervical Lesions in Urban and Rural Areas: An Age-Period-Cohort Analysis.

Disparities in human papillomavirus (HPV) vaccination exist between urban (metropolitan statistical areas (MSAs)) and rural (non-MSAs) regions. To address whether the HPV vaccine's impact differs by urbanicity, we examined trends in cervical intraepithelial neoplasia grades 2 or 3 and adenocarcinoma in situ (collectively, CIN2+) incidence in MSAs and non-MSAs among Tennessee Medicaid (TennCare)-enrolled women aged 18-39 years and among the subset screened for cervical cancer in Tennessee, United States. Using TennCare claims data, we identified annual age-group-specific (18-20, 21-24, 25-29, 30-34, and 35-39 years) CIN2+ incidence (2008-2018). Joinpoint regression was used to identify trends over time. Age-period-cohort Poisson regression models were used to evaluate age, period, and cohort effects. All analyses were stratified by urbanicity (MSA versus non-MSA). From 2008-2018, 11,243 incident CIN2+ events (7956 in MSAs; 3287 in non-MSAs) were identified among TennCare-enrolled women aged 18-39 years. CIN2+ incident trends (2008-2018) were similar between women in MSAs and non-MSAs, with largest declines among ages 18-20 (MSA average annual percent change (AAPC): -30.4, 95% confidence interval (95%CI): -35.4, -25.0; non-MSA AAPC: -30.9, 95%CI: -36.8, -24.5) and 21-24 years (MSA AAPC: -14.8, 95%CI: -18.1, -11.3; non-MSA AAPC: -15.1, 95%CI: -17.9, -12.2). Significant declines for ages 18-20 years began in 2008 in MSAs compared to 2010 in non-MSAs. Trends were largely driven by age and cohort effects. These patterns were consistent among screened women. Despite evidence of HPV vaccine impact on reducing CIN2+ incidence regardless of urbanicity, significant declines in CIN2+ incidence were delayed in non-MSAs versus MSAs.