Human papillomavirus (HPV) is a common sexually transmitted virus with clinical sequelae that affect both men and women.1,2 3 4 5 6 7–9
With only a few exceptions (i.e., emancipated minors), adolescents <18 years old must have parental consent in order to receive the HPV vaccine. Thus, the attitudes and beliefs of parents play a critical role in determining how widely this vaccine is used. Numerous prelicensure studies of parents' views on female HPV vaccination delineated beliefs and attitudes that affected parental acceptability of the vaccine.10–13 14–16
There have been only a few previous studies that have examined parental attitudes about male HPV vaccination in the United States.17–20 19,20
To date, there have been no US-based studies published, which have examined parents' attitudes nationally about male HPV vaccination. Ogilvie et al performed a national study on Canadian parents' views on male HPV vaccination and found that the majority of Canadian parents was supportive of male HPV vaccination.21
To bridge these knowledge gaps, we surveyed a national sample of US parents shortly before the HPV vaccine was licensed for males. The goals of our study were (1) to determine their views on male HPV vaccination in general; (2) to assess which factors were associated with parental intentions to have their own sons vaccinated against HPV in the future; and (3) to evaluate whether presenting parents with different types of “messages” about male HPV vaccination affected their attitudes and intentions for this vaccine. This latter goal was based on previously reported data suggesting that “message framing” could affect parental intentions for HPV vaccination for females.22–25
MATERIALS AND METHODS
Study Design
A cross-sectional, web-based survey was conducted in August 2009, 2 months before the HPV vaccine was licensed for males. Embedded within this survey was a randomized intervention study that tested the effect of different male HPV vaccination messages on parental views about the vaccine. The parent sample was randomly divided to receive one of the 2 educational messages (Fig. 1 )—either a “basic” message about HPV vaccination, or an “expanded” message that included information of the basic message plus additional information about the potential benefits to others of vaccinating males against HPV. Following this, all parents were asked a series of questions regarding attitudes about male HPV vaccination. The study was approved by the Institutional Review Board of University of Michigan.
Figure 1.:
Messages about male HPV vaccination used for the randomized controlled trial.
Study Population
Individuals ≥18 years of age were recruited from the KnowledgePanel of Knowledge Networks (Menlo Park, CA), a survey research firm. This nationally representative panel is derived using random digit dialing methodology supplemented by address-based sampling methods, to create a panel population that includes respondents without “landline” phones. Panel members agree to participate in web-based surveys for a small incentive and are provided internet access and hardware, if necessary. Racial/ethnic minority households are oversampled to ensure adequate representation of these subpopulations. Census-based probability sampling weights are provided to enable derivation of nationally representative estimates from the data. Validity of this approach in deriving nationally representative samples has been confirmed in several studies.26–28
A random sample of 3480 adults from the KnowledgePanel was invited to participate in a 49-item survey that assessed a variety of health issues. Households with parents having children aged 17 years or younger were oversampled (n = 2700) to improve statistical power for assessing parental views on child health issues. This manuscript focuses on the subset of questions related to male HPV vaccination, most of which were asked specifically to parents with male children aged 0 to 17 years living in the household. Two questions (described later in the text) were asked to all parents having children 0- to 17 years old (regardless of their child's gender). “Parents” are defined as those who answered yes to the question “Are you the parent, step-parent, or legal guardian of a child 17 years of age or younger living in your household?”
Survey Measures—Questions for All Parents
Following presentation of the randomized educational message, the general importance of male HPV vaccination was assessed with the question, “If the HPV vaccines were approved for males, and were determined to be safe, affordable, and effective in preventing genital warts and some kinds of genital cancers in males, how important do you think it would be for males to get vaccinated against HPV?” A 4-point Likert scale (not important to very important) was used to assess responses. All parents were also queried about the relative importance of 3 potential reasons for male HPV vaccination (to prevent cancers, to prevent genital warts, or to prevent transmission to females in the future) using a 4-point Likert scale (strongly disagree to strongly agree). Likert scales for each of these variables were later dichotomized (the “importance” scale was dichotomized to not important vs. somewhat important/important/very important; the “agree” scale was dichotomized to strongly agree/agree vs. disagree/strongly disagree). This was done to differentiate between generally positive versus negative attitudes about male HPV vaccination and to improve statistical power because of a skewed distribution of responses.
Survey Measures—Questions Specifically for Parents of Males
Parents' intent to vaccinate their sons against HPV was assessed with a single item. Wording for this question differed based on the age of the oldest male child living in the household. Parents of “young boys” (0–8 years) were asked, “If a safe, effective, and affordable HPV vaccine were available for your son when he becomes an adolescent (ages 11–12), how likely would you be to have him vaccinated?” Parents of “adolescent boys” (9–17 years) were asked, “If a safe, effective, and affordable HPV vaccine was available for your son in the next 1 to 2 years, how likely would you be to have him vaccinated?” This age dichotomy was chosen based on the expectation that future male HPV vaccine recommendations would be similar with regard to age eligibility to that of females.29
Similar to a previous study,10 30 Figure 2 . All scale measures demonstrated reasonable internal reliability (Cronbach alphas ranging from 0.62 [barriers] to 0.97 [normative]).
Figure 2.:
Phrases used to assess parental attitudes in 5 psychological domains.
Survey Measures—Demographic Characteristics
Parent age, gender, race/ethnicity, and education data were provided by Knowledge Networks. Insurance status of the child was based on parent report, and was classified into following 4 categories: public (Medicaid and/or Medicare), private, other (military plan, Indian Health Service, etc.), or no insurance.
Statistical Analyses
Descriptive statistics were generated for each variable. Bivariate associations were assessed using Pearson χ2 tests and univariate logistic regression. Independent predictors of parental HPV vaccination intention were assessed with separate multivariable logistic regression models for young or adolescent boys. Each model included the demographic variables reaching statistical significance (P ≤ 0.05, 2-sided) in bivariate analyses, plus all the psychological domain scale measures as these were hypothesized a priori to be associated with vaccination intention. Wald tests were used to assess the effect of adding or removing demographic variables to/from the models. All results incorporate probability sampling weights to derive national estimates. Analyses were performed using STATA 10 software (Stata Corporation, College Station, TX, 2003).
RESULTS
Response Rate
The overall survey response rate (parents and nonparents) was 68%. Among parents specifically, the survey response rate was 62% (1678 parent respondents out of 2700 parents invited to participate in the survey). There were 1178 parents who indicated that they had at least 1 male child aged 0 to 17 years currently living in the household. Characteristics of the entire parent respondent sample are presented in Table 1 . Briefly, the majority of the sample belonged to white race (65%), females (54%), and was between the ages 30 to 44 years (56%). The majority of sons (59%) had private health insurance. For each variable listed in Table 1 , there were no significant differences between the total parent sample and the subsample of parents with boys (data not shown). No data were available for nonrespondents.
TABLE 1:
Effects of Different Messages About Male HPV Vaccination
Demographic characteristics of parents were similar between the 2 message groups (data not shown). Receiving the basic versus expanded message about male HPV vaccination had no effect on the proportion of parents believing that male HPV vaccination was generally important, or on the specific reasons for having their sons vaccinated (data not shown). In bivariate analyses, vaccination intent (being likely or very likely to have their sons vaccinated in the future) was higher for those who had received the basic message (60%) when compared to those receiving the expanded message (46%, P < 0.02), but only among parents of older boys. However, this association was no longer significant when the analyses were adjusted for other variables (see description of the multivariable analysis is provided in the Parental Intention section mentioned later in the text).
Perceived Importance of Male HPV Vaccination by Parents
Among the total parent sample, 90% agreed that it was either important or very important for males to “get vaccinated against HPV”; results were similar (89%) for the parents of boys subsample. There was universal agreement (100%) that male HPV vaccination was important for preventing transmission to future female partners, whereas 93% agreed that it was important to prevent male genital cancers and 91% agreed that it was important to prevent male genital warts. Interestingly, among the 10% of parents who did not agree that it was generally important to have males vaccinated against HPV vaccination, a high proportion indicated male HPV vaccination was important to prevent transmission (100%), male genital cancers (61%), and male genital warts (55%).
The belief that male HPV vaccination was generally not important was associated with a number of demographic characteristics in the general parent sample (Table 2 ). Fathers, whites and those of “other” race, parents with higher education, parents who had sons, and parents whose sons had no health insurance were significantly more likely to believe male HPV vaccination was generally not important than their comparative groups.
TABLE 2:
Parental Intention for Male HPV Vaccination
Among parents with sons, the factors associated with vaccination intent differed depending on their child's age category (Table 3 ). Among parents of young boys (ages 0–8 years), 53% would be likely or very likely to have their son vaccinated against HPV “when he becomes an adolescent at age 11 to 12.” All 5 psychological constructs were associated with this outcome in bivariate analyses—specifically vaccination intention increased with increased perceived benefits of vaccination, perceived susceptibility to illness, perceived severity of illness and normative influence, and vaccination intention decreased with higher perceived barriers to vaccination. Of the 5 psychological constructs, 4 (all but perceived severity) maintained this association in multivariable models adjusted for parent's race, education, gender, and insurance status of son. Perceived benefits and normative influences had the largest influence on vaccination intent (Table 3 ). There was no association with demographic characteristics and vaccination intent in either the bivariate or multivariable analyses for parents of young boys.
TABLE 3:
Among parents of adolescent boys (9–17 years), 48% were likely or very likely to have their sons vaccinated against HPV in the “next 2 to 3 years.” This proportion was not significantly different than that of parents of young boys (data not shown). Again, the 5 psychological constructs were significantly associated with vaccination intent in bivariate analyses (Table 3 ). In addition, bivariate analyses demonstrated increased vaccination intention among those of black race, lower education, and mothers and lower vaccination intention among those with no insurance and who received the expanded message. In the multivariable model however parent's gender, message type, and insurance status were no longer significantly associated with vaccination intent (Table 3 ).
DISCUSSION
In this first national assessment of parental attitudes about male HPV vaccination in the United States, 90% of parents indicated that male HPV vaccination was generally important. However, only approximately one-half of parents of boys intended to have their own sons vaccinated against HPV as an adolescent. Intent to vaccinate against HPV was independently associated with several psychological constructs that corresponded to parental attitudes about HPV infection and vaccination. Among parents of adolescent boys (9–17 years), but not among parents of young boys (0–8 years), higher vaccination intent was also associated with having less than a high school education and with black race.
Our study assessed parental intentions regarding male HPV vaccination immediately before when the quadrivalent HPV vaccine was licensed for this gender. Prevention of genital warts was the first indication for male HPV vaccine administration,31 32
Male HPV vaccination uptake may also be hindered by modest levels of parents' future intent to vaccinate their own sons against HPV (48%–53%, depending on age). On the basis of validated models of health behavior,30,33 10,13,34,35 14
Consistent with previous studies of female adolescent HPV vaccination, parental intent for male HPV adolescent vaccination was associated in our study with psychological constructs measuring parents' beliefs about HPV infection and vaccination. Perceptions that the vaccine would provide substantial health benefits and that their family and friends would be supportive of vaccination had the strongest association with vaccination intention—a finding that is consistent with studies of female HPV vaccination. Interestingly, we found that perceived severity of infection (i.e., how “bad” it would be if their sons were infected with HPV) was not associated with male HPV vaccination intent in multivariable models. This suggests that educational messages highlighting the risks of not vaccinating may be ineffective at swaying parental attitudes about male HPV vaccination. Rather, our results suggest that strong positive messages from medical personnel and information specifically about the health benefits of male HPV vaccination may be preferable.
In addition to the psychological constructs, black race and having less than a high school education were associated with higher vaccination intent in the multivariable model for parents of adolescent boys, but not for parents of young boys. The reason for this age-based discrepancy in results is not clear, but we hypothesize that the perceived “immediacy” of the vaccination decision among parents of adolescent boys may have uncovered some subtle differences in parental attitudes about male HPV vaccination that vary based on these factors. Previous research has demonstrated that minority race and lower education are associated with increased HPV vaccine series initiation but decreased vaccine series completion in women.36–38 39
Work by others has demonstrated that message “framing” can have an important role in the acceptability of HPV vaccination.22–25
Our study has several other limitations. First, as with any survey-based research, response bias could have affected our results. Participants were registered panelists recruited by a survey research firm and therefore may have had inherently higher interest in study participation. This concern is mitigated somewhat by the fact that participants were unaware of the survey content before agreeing to complete it. Second, web-based surveys have the potential to inadequately represent underserved populations. However, under-represented racial/ethnic minorities were purposefully oversampled during panel recruitment, and internet access and software were provided to participants when needed. The use of survey panels and a web-based platform has been shown previously to provide valuable, nationally representative information about a variety of health care-related behaviors.40–42
CONCLUSION
As HPV vaccination for men is initiated in the United States, the results of this national study indicate that parents are already convinced of the general importance of HPV vaccination for adolescents. However, only one-half of parents with male children intended to have their son vaccinated against HPV in the future as an adolescent. Vaccination intent was most strongly associated with perceptions that the vaccine had significant health benefits, that family and friends supported the decision to vaccinate, and that barriers to vaccination were few. Black race and having less than a high school education were also associated with higher vaccination intention among parents of adolescent boys, but not among parents of younger boys. These findings may inform future educational campaigns about male HPV vaccination.
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