Is the positive predictive value of high-grade cytology in predicting high-grade cervical disease falling due to HPV vaccination?

A fall in the positive predictive value (PPV) of cytological predictions of high-grade squamous intra-epithelial lesions (HSIL) or adenocarcinoma-in-situ (AIS) has been predicted in the post-HPV vaccination era due to the decrease in underlying prevalence of cervical lesions. Data was extracted from the Victorian Cervical Screening Registry including cervical cytology tests taken between 2000 and 2016 and any subsequent histology performed within 6 months of the cytology. PPV was calculated for each age group (<20, 20-24, 25-29, 30-34, 35-39, 40-49, 50-59, 60-69, 70+ years) and calendar year. The x2 (chi-square) test was used to identify significant trends in PPV over time in each age group in both the pre-vaccination (2000-2006) and the post-vaccination (2007-2016) periods. The overall PPV of HSIL/AIS cytology in predicting histologically confirmed high grade disease (HGD, HSIL/AIS+) was 75% and this was consistent across the different calendar years. When stratified by age group, there was a decreasing trend in the PPV in women aged <20 years (ptrend = 0.0006) and 20-24 years (ptrend = 0.0004) in the post-vaccination period but not in the pre-vaccination period (ptrend = 0.82 and ptrend = 0.73, respectively). No such decline in PPV was noted in either the pre-vaccination or the post-vaccination periods for any other age groups except the oldest women, aged 60-69 years and 70+ years. The decline in PPV of HSIL/AIS cytology in predicting HGD in age groups <20 and 20-24 years in the post-vaccination period could be an impact of the HPV vaccination.