Our analysis of a nationally representative sample from the 2008 Health Information National Trends Survey found that the vast majority of women are aware of the need to continue cervical cancer screening with Pap tests after receipt of the HPV vaccine. We found higher levels of knowledge regarding the need for screening after vaccination than a national survey conducted in late 2007;17
this may reflect differences in question wording and research methods between the two surveys, or slight improvements in public awareness and understanding of HPV over the course of 2008. In our data, knowledge of screening requirements varied little across income, education, or racial/ethnic groups, suggesting that subgroups of women with traditionally lower rates of cervical cancer screening are appropriately informed about the need for continued screening after HPV vaccination.
Our additional analysis of a nationally representative sample from the 2008 National Health Interview Survey found that the vast majority of young adult women who initiated the HPV vaccine series reported that they intend to receive a Pap test within the next three years, in accordance with cervical cancer screening guidelines.24–26
This finding is not surprising, because young adult women who are early adopters of the HPV vaccine may have been motivated to vaccinate by the same strong orientation toward preventive care that lead them to receive other vaccines19–20, 28
and to participate in regular cervical cancer screening. Although women who received the HPV vaccine during its initial two years on the market were more likely to plan future Pap testing at recommended intervals than unvaccinated women, it remains to be seen whether adult women who are later adopters of the vaccine will mimic this pattern, as these women may not be as inclined toward preventive services as their early adopting peers.
It is important to note that the priority target populations for HPV vaccination are pre-adolescent and adolescent girls,23
and that women who are vaccinated in young adulthood differ from those who are vaccinated in pre-adolescence and adolescence on several important sociodemographic and health care access characteristics. Nationwide, HPV vaccine coverage in young adult women is approximately 12%,20, 28
with substantially higher rates of vaccination among those with higher income,20
health insurance,20, 28–29
and a recent physician visit.17, 19, 30
In contrast, national vaccination rates are substantially higher among pre-adolescents and adolescents than among adults.31
Factors associated with cervical cancer screening participation among the current cohort of women who vaccinated as adults, such as education, income, health insurance, and preventive care orientation, may not be correlated with HPV vaccination status in the future, as the cohort of adolescent girls who received the vaccine through public financing programs age into young adulthood. Because decisions about adolescent vaccination are primarily made by parents and may reflect the preventive orientation of the parent rather than the adolescent, cervical cancer screening intentions and practices may differ for women who were vaccinated as pre-adolescents and adolescents than for those who vaccinate in adulthood.
As the HPV vaccine and HPV DNA tests are further incorporated into cervical cancer prevention policy,32
cervical cancer screening guidelines may evolve. Policy analyses of HPV vaccine strategies suggest that widespread HPV vaccination is more cost-effective if cervical cancer screening is initiated later or screening intervals are less frequent.33
However, Pap testing earlier and more frequently than recommended (e.g., a screening interval of less than 3 years) was common even before the introduction of the HPV vaccine,34–35
perhaps reflecting physicians’ disagreement or slow response to rapidly changing and conflicting guidelines,36
women’s enthusiasm for participating in routine cancer screening,37
or financial incentives for frequent screening.38
Our findings may foretell patients’ desire to continue screening at pre-vaccine intervals, even if updated clinical guidelines recommend less frequent screening.
Our study is subject to several limitations. First, on NHIS 2008, only those who had ever had a Pap test were asked about their intention to participate in cervical cancer screening in the future; thus, we cannot calculate intention to participate in Pap testing among young women who have not initiated screening. However, vaccinated women were no more or less likely than unvaccinated women to have initiated Pap testing. The small subset of the general population that does not participate in cervical cancer screening stands to benefit most greatly from HPV vaccination; should unscreened women also go unvaccinated, disparities in cervical cancer outcomes could worsen as vaccine coverage increases. Our data did not allow us to explore this concern.
Second, the total number of HPV-vaccinated women in the NHIS sample is small. Sample size may have limited our ability to detect significant associations between respondent characteristics and intention to participate in future Pap tests.
Third, like many recent large surveys that sample households with landline telephones, HINTS 2008 has a modest response rate, and may under-enumerate 18 to 34 year olds, those with less than a high school education, minorities and those in low income groups.39
Weighting calibrations use many of these variables and should compensate for possible biases to the extent that survey respondents are similar in cervical cancer prevention behaviors to those who were not invited or did not choose to participate.
Fourth, on HINTS 2008, only those contacted by telephone and those who had heard of HPV were asked whether they knew about continued need for cervical cancer screening after the HPV vaccine; previous analyses of HINTS data have shown that women who have heard of HPV are more likely to be younger than age 65, non-Hispanic White, and have higher income and education.16
Given the uniformity of our outcome across sociodemographic groups, however, it seems unlikely that either of these two limitations would create a systematic bias in our results.
Finally, although the HPV vaccine is recommended primarily for adolescents, HINTS data are collected only from adults, and adolescent respondents to the NHIS are not asked about their intention to participate in Pap testing in the future. Future research should examine cervical cancer screening knowledge and intentions among those who received HPV vaccines in adolescence.
Our study provides encouraging preliminary evidence that adult women are knowledgeable about the importance of continued cervical cancer screening after receipt of the HPV vaccine and that those vaccinated in young adulthood are likely to continue to participate in Pap testing. As time elapses, further studies will be needed to monitor cervical cancer screening knowledge and behaviors among adult women who are later adopters of the vaccine and to examine whether vaccinated adolescent females are aware of, and adhere to, screening guidelines as they become eligible.