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This journal club notes article discusses the incidence, types, and coverage of HPV-associated cancers, as well as factors associated with HPV vaccination. It also explores the use of nested case-control study design and proposes the need for a 14vHPV vaccine.
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Journal Club Notes Martha A. Wojtowycz, PhD March 22, 2019
Learning Objectives • Describe the incidence of HPV-associated cancers by sex, cancer type, and race/ethnicity • Identify the most common HPV types attributable to the various HPV-associated cancers • Discuss HVP immunization coverage rates by sex, socioeconomic status and geographic location • Identify factors associated with HPV intent to vaccinate and with vaccination rates • Explain a nested case-control study design and when you would use it • Discuss the proportions of vulvar and vaginal lesions attributable to HPV that are not covered by the current 9vHPV vaccine
Number of New HPV-associated Cancers, 2010-2014 Source: CDC, 2018.
Incidence Rate of HPV-associated Cancers, 2010-2014by Sex and Race/Ethnic Groups (age-adjusted rate per 100,000) Source: CDC, 2018.
HPV Vaccine • Currently in the United States only 9vHPV is available for both females and males • Protects against HPV types 6/11/16/18/31/33/45/52/58 which account for about 80% of HPV-associated cancers • Previously used 4vHPV for both females and males which protected against 6/11 which account for over 90% of genital warts and 16/18 which account for the majority of cancers • Previously also used 2vHPV on females to protect against 16/18 • New dosing recommendations: • 2 doses if start series prior to age 15; second dose 6-12 months after the first • Need three doses if immunocompromised or second dose received at less than 5 months after first dose • 3 doses if start series between ages 15-26; with dosing at 0, 1-2 months, and 6 months
Estimated Vaccination Coverage Among Adolescents Aged 13-17 years, United States 2017 Source: Morbidity and Mortality Weekly Report, 67 (33), August 24, 2018.
Factors Associated with HPV Vaccination • Predictors of parental intent to vaccinate • Mother’s education – strongest predictor with lower education associated with higher intent • Race/ethnicity – strong predictor with Hispanic associated with higher intent • Predictors of actual receipt of vaccine • Provider recommendation – strongest predictor of higher receipt • Stronger association for males than for females
Garland SM et al., “Human Papillomavirus Genotypes From Vaginal and Vulvar Intraepithelial Neoplasia in Females 15-26 Years of Age”, Obstetrics and Gynecology, vol. 132, no. 1, August 2018.
Nested Case Control Study Design • Nested case control studies are set within formed cohort studies and are typically conducted when you want to do testing on samples (e.g., specimens, blood, etc.) that were collected on the whole cohort but were not analyzed • Cases: The study subjects with the disease • Those who developed cervical or anogenital lesions during the four-year follow-up period • Controls: A sample of the study subjects without the disease • Those who did not develop cervical or anogenital lesions during the four-year follow-up period • 5 controls per case randomly selected from group who did not develop lesions
Nested Case Control Study Design • Why use this study design? • Significant time savings – do not have to start a new study • Reduced efforts in data collection and analysis • Reduced in costs – do not have to study the entire cohort; some tests are very expensive • Statistical results minimally affected • Preserve some specimens, blood, etc. for future analyses
% that tested (+) for one or more of the 14 HPV types These 5 HPV types are not covered by the 9vHPV vaccine. What proportion of lesions are attributable to these types?
Previous studies have found over 90% of vaginal lesions due to HPV % not covered by 9vHPV