Risk stratification using human papillomavirus testing among women with equivocally abnormal cytology: Results from a state-wide surveillance program

Background: Clinical guidelines for cervical cancer screening have incorporated comparative risks of cervical intraepithelial neoplasia grade 3 or cancer (CIN3⁺) for various screening outcomes to determine management. Few cohorts are large enough to distinguish CIN3⁺ risks among women with minor abnormalities versus negative cytology because of low incidence. The New Mexico Human Papillomavirus (HPV) Pap Registry offers a unique opportunity to evaluate cervical cancer screening in a diverse population across a broad-spectrum of health service delivery. Methods: Kaplan-Meier and logistic-Weibull survival models were used to estimate cumulative risks of CIN3⁺ among women ages 21 to 64 who were screened in New Mexico between 2007 and 2011 with negative, equivocal or mildly abnormal cytology, that is, atypical squamous cells of undetermined significance (ASC-US; with or without HPV triage), or low-grade squamous intraepithelial lesions (LSIL). Results: We identified 452,045 women meeting the selection criteria. The 3-year CIN3⁺ risks for women with negative, ASC-US, and LSIL cytology were 0.30%, 2.6%, and 5.2%, respectively. HPV triage of ASC-US stratified 3-year CIN3⁺ risks were 0.72% for HPV-negative and 7.7% for HPV-positive. Risks tended to decline after age 30 for all screening results. Conclusions: In this state-wide population-based cohort, cytology and HPV triage of ASC-US stratified women's CIN3⁺ risk into similar patterns observed previously, suggesting the validity of screening guidelines for diverse populations in the United States. Absolute risk estimates should be compared across other large populations. Impact: Strategies for HPV triage of ASC-US derived from clinical trials are upheld in large clinical practice settings and across diverse screening populations in the United States.