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.

HPV vaccination coverage and course completion rates for Indigenous Australian adolescents, 2015.

OBJECTIVE: To estimate human papillomavirus (HPV) vaccination coverage and course completion rates for Indigenous adolescents in four Australian states and territories. PARTICIPANTS, SETTING: Adolescents who were 12 years old in 2015 and received the quadrivalent HPV vaccine (three doses: 0, 2, 6 months) as part of the National HPV Vaccination Program in 2015 or 2016 in New South Wales, Queensland, the Northern Territory, or the Australian Capital Territory. MAIN OUTCOME MEASURES: Estimated HPV vaccination coverage by dose and by Indigenous status and sex, based on National HPV Vaccination Program Register data; vaccination course completion rates (proportion of dose 1 recipients who received dose 3) for 12-year-olds vaccinated during 2013-2016, by sex, jurisdiction, and Indigenous status. RESULTS: Dose 1 coverage exceeded 80% for all Indigenous status/jurisdiction/sex groups (range, 83.3-97.7%). Coverage was similar for Indigenous and non-Indigenous girls in Queensland (87.3% v 87.0%), lower for Indigenous girls in the ACT (88.7% v 97.7%) and the NT (91.1% v 97.0%), and higher in NSW (95.9% v 89.9%); it was similar for Indigenous and non-Indigenous boys in all jurisdictions except the NT (88.6% v 96.3%). Dose 3 coverage (range, 61.2-87.7%) was markedly lower for Indigenous than non-Indigenous 12-year-olds in all jurisdictions, except for girls in NSW (82.6% v 83.6%). CONCLUSION: HPV vaccine coverage is high, but course completion is generally lower for Indigenous adolescents. Strategies for improving completion rates for Indigenous Australians are needed to end the higher burden of cervical cancer among Indigenous than non-Indigenous women.

Effective HPV vaccination coverage in Australia by number of doses and two-dose spacing: What if one or two doses are sufficient?

BACKGROUND: Initially, three-dose schedules were recommended for vaccines against human papillomavirus (HPV); subsequently recommendations have been updated to a schedule of two doses delivered at least six (minimum five) months apart for those aged <15 years at dose 1. We aimed to re-estimate effective HPV vaccination coverage in Australia, considering reduced-dose schedules and possible one-dose effectiveness. We also aimed to identify which of the three school visits was most commonly missed amongst two-dose only recipients, to inform optimal timing of visits. METHODS: National vaccination register data were used to estimate: i) vaccination coverage at December 2017, either with a complete course (three or two sufficiently-spaced doses (>151 days apart)), or at least one dose; ii) for each birth cohort offered vaccination, the percentage of the initially targeted cohort with a complete course, or at least one dose (reflecting uptake at the time the vaccine was offered); and iii) among two-dose only recipients, the percentage who missed each of three school visits. RESULTS: Including those with two sufficiently-spaced doses increased end-2017 coverage by 1.3-2.8% points in those vaccinated at school. Including those with at least one dose increased coverage further, by 6.5-9.5% points, mostly due to including those receiving multiple too-closely-spaced doses. One-dose coverage reached 90.9% and 86.9% in females and males respectively born in 2002. Among those vaccinated at school who received only two doses, it was much more common to miss the first (31.0% females; 32.5% males) or the third visit in the school year (54.6% females; 48.6% males) than the second (14.1% females; 18.8% males). CONCLUSIONS: Including those with two sufficiently-spaced doses has a very modest impact on HPV vaccine coverage in Australia. If receiving at least one dose offers substantial protection, these data suggest that the school-based program is now achieving close to 90% coverage on this measure.