Test Performance of Cervical Cytology Among Adults With vs Without Human Papillomavirus Vaccination.

Importance: Current US cervical cancer screening guidelines do not differ by human papillomavirus (HPV) vaccination status. However, as the positive predictive value (PPV) of a screening test decreases, the risk of a false-positive result increases. Objective: To evaluate whether HPV vaccination is associated with decreased PPV for abnormal cervical cytology. Design, Setting, and Participants: This retrospective cohort study conducted via electronic medical record review included eligible patients aged 21 to 35 years who had at least 1 cervical cytology result within a single health system between January 2015 and December 2018. The health system comprises a partnership between an academic health center and a private not-for-profit health center. Patients with abnormal screening cytology and no diagnostic test results were omitted from analysis. Data were analyzed from December 2019 to November 2021. Exposures: HPV vaccination, defined as receiving at least 1 dose of HPV vaccine. Subgroup analyses were performed for those completing all vaccination doses per Advisory Committee on Immunization Practices guidelines and by age at vaccination initiation, dichotomized as younger than 21 years vs 21 years or older. Main Outcomes and Measures: PPV of abnormal cervical cytology for risk of cervical intraepithelial neoplasia (CIN) 2 or more severe diagnosis. Results: A total of 46 988 patients (mean [SD] age, 28.7 [4.5] years; 3058 [6.5%] Asian; 4159 [8.9%] Black or African American; 35 446 [75.4%] White) were included; 15 494 (33.0%) were at least partially vaccinated, and 4289 (9.1%) had abnormal cytology results during the study period. Among the individuals with abnormal cytology, the PPV for CIN 2 or more severe diagnosis was lower among vaccinated individuals (17.4%; 95% CI, 16.4%-18.4%) than unvaccinated individuals (21.3%; 95% CI, 20.4%-22.3%). Among vaccinated individuals, PPV was significantly lower among those completing vaccination (15.9%; 95% CI, 14.9%-17.0%) than those with incomplete vaccination (22.4%; 95% CI, 20.0%-25.0%), especially among those initiating vaccination when younger than 21 years (11.9%; 95% CI, 10.9%-12.9%) vs those initiating at age 21 years or older (30.7%; 95% CI, 27.3%-34.4%). Conclusions and Relevance: Among a population with relatively low HPV vaccine coverage, the PPV of cervical cytology for CIN 2 or more severe diagnosis was significantly lower among vaccinated individuals. PPV will likely further decrease in the future as a population with higher HPV vaccination coverage ages into screening. Confirmation of these results will call for changes in screening strategies, particularly for completely vaccinated individuals who initiated vaccination when younger than 21 years.