Public Health Nursing 0737-1209/© 2015 Wiley Periodicals, Inc. doi: 10.1111/phn.12198
POPULATIONS
AT
RISK ACROSS
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LIFESPAN: POPULATION STUDIES
Factors Related to Human Papillomavirus (HPV) Vaccination in College Men Nop Thodsama Ratanasiripong, Ph.D, R.N, C.C.R.C School of Nursing, California State University, Dominguez Hills, Carson, California Correspondence to: Nop Thodsama Ratanasiripong, School of Nursing, California State University, Dominguez Hills, 1100 E. Victoria St., Carson, CA 90747. E-mail: [email protected]
ABSTRACT Objectives: To examine the vaccination rate and identify factors influencing HPV vaccination among college men. Design and Sample: This cross-sectional study, guided by Theory of Planned Behavior, was conducted with a convenience sample of college males (18–26 years of age). A web-based survey was sent to 3,300 students attending a public university in California. Measures: The questionnaire used in the study—HPV/HPV vaccine-related Knowledge, Attitudes, and Behaviors—was adapted from a prior study conducted among college women. Demographic and sexual history information was also obtained. Results: Four hundred and ten respondents were qualified for analysis. HPV vaccination rate was approximately 11.8%. Overall, young men had quite low HPV/HPV vaccine knowledge. Both nonvaccinees (n = 48) and vaccinees (n = 141) had positive attitudes toward the HPV vaccine, including mandating vaccination. Knowledge and attitudes toward the vaccine were not directly associated with the outcomes of vaccination status and intention. Both outcomes could be predicted by the attitude toward getting vaccinated against HPV. Intention was also predicted by subjective norm. Conclusion: Interventions to increase the vaccination rate should focus on creating positive attitude toward getting vaccinated against HPV through behavioral beliefs. Increasing the subjective norm will be beneficial. Key words: Human Papillomavirus, vaccination, men.
Background Human Papillomavirus (HPV) is responsible for most of both incident and prevalent sexually transmitted infections (STIs) in the United States (Satterwhite et al., 2013). Approximately, 14 million Americans aged 15–59 years are newly diagnosed with HPV each year and half of them are young adults aged 15–24 years (Markowitz et al., 2014). Similar to females, the prevalence of genital HPV infection is estimated to be at least 20% in the male population (Dunne, Nielson, Stone, Markowitz, & Giuliano, 2006). In the United States, 20,000 women and 12,000 men are diagnosed with HPV-related cancers each year (Centers for Disease Control and Prevention [CDC], 2014a). Specifically,
men who have sex with men (MSM) are 17 times more likely to develop HPV-related anal cancer than heterosexual men (CDC, 2011a). While most HPV infections (70–90%) may clear by themselves in 3 years, HPV can also cause genital warts and anogenital cancers (e.g., cervical, vaginal, anal, and penile cancers) (Frazer et al., 2006). HPV infection and anogenital cancer morbidity not only result in emotional and physical distress at the individual level but also result in increased health care costs. Currently, HPV is the second most expensive STI, following HIV. In the United States, 1 to 6 billion dollars are annually exhausted for cervical/anal cancer screening and treatments (Frazer et al., 2006).
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The primary route of genital HPV infection is sexual intercourse, both vaginal and anal. HPV transmission occurs via skin-to-skin contact, but penetration of the vagina or anus is not essential (Stanley, 2010). Regular and consistent use of condoms offers only partial protection (60%) against HPV infection (Winer et al., 2006). Because most HPV-infected persons do not show obvious signs or symptoms, it has been challenging to develop HPV detection and prevention programs. The opportunity for HPV prevention was presented with the licensing of an HPV vaccine in the United States. The HPV vaccine (Gardasil) was first approved for females aged 9–26 in 2006 and for males aged 9–26 in 2009 (CDC, 2013). Despite the vaccine being considered a medical breakthrough (Radhakrishnan, 2006), national data show considerably low HPV vaccination rates. For adolescents aged 13–17, 44.3% have received at least one dose and 26.7% have received three doses of the HPV vaccine. For young women aged 19–26, only 17.1% have received at least one dose of the HPV vaccine (CDC, 2011b). Because of such results, a variety of HPV vaccine promotion and research studies have been done in attempt to increase the HPV vaccination rate among women. For young men, HPV vaccine related-research is sparse. The vaccination rate among boys/men is currently unknown, as is an understanding about what influences on college men’s decision to obtain the HPV vaccine. This information can provide the basis for HPV prevention and vaccination programs for all genders. This cross-sectional study used a theory-driven approach to: (1) examine the vaccination rate and (2) identify factors influencing HPV vaccination among college men. The Theory of Planned Behav-
Figure 1. The Study Theoretical Framework
ior guided the study and provided a framework for understanding the factors associated with vaccination and vaccination intention. The study’s theoretical framework is illustrated in Figure 1. The Theory posits that a person’s behavior (i.e., getting vaccinated against HPV) is determined by the intention to perform such behavior. Intention is influenced by the attitude toward the behavior, subjective norm, and perceived behavioral control (Ajzen, 1991). Variables such as demographic characteristics, past behavioral experiences, knowledge, and attitude toward an object are considered as indirect factors that may impact the intention and behavior through attitude toward the behavior, subjective norm, and perceived behavioral control (Ajzen, 1991). The attitude toward an object (e.g., hamburger, vaccine, and ethnicity) is considered to be general and broad. This type of attitude is only remotely linked to intention and the behavior in question. The attitude toward a behavior is the attitude toward performing the specific behavior with respect to an object/target (e.g., eating a hamburger, getting vaccinated against HPV, hiring an Asian-American). This type of attitude is directly linked to the intention and behavior (Ajzen & Fishbein, 2005). Subjective norm is one’s perception of what significant others expect of him/her. Perceived behavioral control is one’s confidence to perform a behavior in question (Ajzen, 1991).
Methods Design and sample Setting and population. This cross-sectional study was conducted with a convenience sample of college men ages 18–26 attending a public university
Ratanasiripong: Factors Related to HPV Vaccination in College Men in southern California. The maximum age range was consistent with the 26 years of age limit to be vaccinated against HPV. Sample size. Based on regression analysis and the following parameters—a power of 0.9, with small effect size (0.1), alpha equals 0.05, and three direct predictors (attitude toward getting vaccinated, subjective norms, perceived behavioral control)—a minimum of 159 subjects was needed (Faul, Erdfelder, Buchner, & Lang, 2009). Procedures for data collection. After Institutional Review Board’s approval, 3,300 random e-mail addresses of male students were obtained from the university. An invitation was emailed to the potential research subjects in which students were directed to click on a web-based survey link (SurveyMonkey) if they wished to participate in the study. After reading the informed consent page, the students who agreed to participate completed the survey. To enhance the response rate, an e-mail reminder was sent to the students 1 and 2 weeks after the first invitation. Students who did not wish to receive reminders could request their e-mail addresses be taken off the list. A prize strategy was also applied as an incentive. The respondents had the opportunity to draw a prize, if they were one of the first 210 respondents who completed the survey and emailed the researcher to request a prize drawing (four $100, six $ 50, and 200 $10 gift cards). The researcher drew the prize and mailed the gift cards to the respondents unless they wished to pick it up on campus. The web-based survey was deactivated 1 month after the invitation was sent out. To provide anonymity for the respondents, the IP address tracking function on SurveyMonkey was disabled.
Measures The questionnaire used in this research—HPV and HPV vaccine-related Knowledge, Attitudes, and Behaviors—was adapted from the researcher’s prior study conducted among college women (Ratanasiripong, Cheng, & Enriquez, 2013). The questionnaire was developed using constructs of the Theory of Planned Behaviors and was reviewed for face and content validity. Reliability from the prior study data indicated the Cronbach’s coefficient alphas of all scales (attitudes, subjective norms, perceived
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behavioral control, and vaccination intention) were between 0.71 and 0.93 (Ratanasiripong et al., 2013). The questionnaire included (1) nine items to measure HPV/HPV vaccine knowledge (true/false); (2) nine items to measure attitudes toward the HPV vaccine (semantic differential scale); (3) six items to measure attitudes toward getting vaccinated against HPV (semantic differential scale)— for nonvaccinees (subjects who have not obtained the vaccine), the statement of attitude was “my getting vaccinated against HPV would be. . .”; for vaccinees (subjects who have obtained the vaccine), the statement of attitude was “I thought that my getting vaccinated against HPV would be. . .”; (4) five items to measure subjective norms (Likert scale)—the present tense was used in the statements for nonvaccinees, while the past tense was used in the statement for vaccinees (e.g., “I feel under social pressure to get vaccinated against HPV” vs. “I felt under social pressure to get vaccinated against HPV”); (5) four items to measure perceived behavioral control (Likert scale)—the present tense was used in the statements for nonvaccinees, while the past tense was used in the statement for vaccinees; and (6) four items to measure vaccination intention (Likert scale) among nonvaccinees only. Vaccination intention was measured only among the male respondents who have not received the vaccine. In addition to the questionnaire items, the survey asked about vaccination status, demographic, sexual history, and sexual experiences. Cronbach’s coefficient alphas of all scales remained in the range of 0.69–0.95.
Analytic strategy The study data were analyzed using SPSS 20.0. Descriptive statistics were used to describe demographics, sexual history, and vaccination status. Depending on the variables’ level of measurement, independent t test and chi-square tests were used to determine the differences in the demographic and sexual history variables between those who have obtained the vaccine and those who have not. Pearson’s or Spearman’s correlation coefficients were used to determine the relationships between the respondent characteristics, indirect predictors (HPV knowledge, attitudes toward the vaccine), direct predictors (attitudes toward getting vaccinated against HPV, subjective norm, and perceived behavioral
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control), and the outcome variables—intention to obtain the vaccine and vaccination status. Two separate regression analyses were used to determine the relative contribution of the predictor variables to the outcome variables. For the vaccination status, hierarchical logistic regression was conducted by controlling a significant demographic (age). For the vaccination intention, hierarchical multiple regression was conducted by controlling a significant indirect predictor (attitudes toward the vaccine).
Results Out of 3,300 students, 451 agreed to participate, for a response rate of 13.7%. Among these, 41 were not qualified because more than 20% of items were missing or they failed on attention-testing items (which indicated if the respondents paid attention to answer the questions). Among the 410 qualified respondents, 210 (51.2%) were aware of the HPV and HPV vaccine. Of 210 respondents, 48 (22.9%) received at least one dose of the HPV vaccine (vaccinees), 141 (67.1%) had not obtained the vaccine (nonvaccinees), and 21 (10%) preferred not to answer, making 189 respondents available for further analysis (Fig. 2). In assuming that those who were unaware of the HPV/HPV vaccine had not received the vaccine, the vaccination rate was approximately 11.7% (48 out of 410 respondents).
Sample characteristics Demographic. As shown in Table 1, age was the only variable that was significantly associated with the vaccine status (p = .002). More than half of the participants in both groups (nonvaccinees and vaccinees) were Latinos (50.7% and 60.4%, respectively). Similarly, more than half in both groups reported that they were Christian (e.g., Protestant, Catholic, nondenomination). Close to 75% of both groups noted that they had health insurance and that they were in nonhealth-related majors. Sexual history. As shown in Table 1, both nonvaccinee and vaccinee groups shared similar sexual history. The majority of them were either single or dating. Over 75% of both groups reported having had sexual intercourse and the majority of them had sex with women. With the nonvaccinee group, the average age of first sexual intercourse
Figure 2. Summary of the Number of Responses was 17.2, and within the vaccinee group, the average age of first sexual intercourse was 16.85. The difference of age of first sexual intercourse was not statistically significant (p = .52). Over 90% of participants who had had sexual intercourse had never been diagnosed with a STI.
Description of the variables Indirect predictors. Of 9 points, the mean score of HPV/HPV vaccine knowledge among nonvaccinees was 5.73 (SD = 2.23) and among vaccinees was 6.10 (SD = 2.36). The difference of the knowledge mean scores between the two groups was not statistically significant, t (187) = 0.99, p = .33. Most respondents (over 75%) in both groups knew that condoms provided partial protection against HPV, that transmission of HPV can occur during the asymptomatic period, that not only sexually active men should receive the HPV vaccine, and that the HPV vaccine does not protect against other STIs. On the opposite end of the spectrum, less than or about half knew that HPV
Ratanasiripong: Factors Related to HPV Vaccination in College Men TABLE 1. Demographic Characteristics and Sexual History of Respondents* Nonvaccinees
Age Ethnicity Caucasian
Vaccinees
(%)
(%)
p-value
M = 22.4(n = 128)
M = 21.0(n = 43)
.002a
(n = 138)
(n = 48)
b
13.8
6.3
Asian
18.1
8.3
Latino
50.7
60.4
Black
9.4
16.7
Other
7.9
Religion Christianity
8.4
(n = 138)
(n = 48)
55.1
62.5
Other
18.8
14.6
None
26.1
22.9
(n = 138)
(n = 48)
Yes
65.2
66.7
No
34.8
33.3
Insurance status
(n = 136)
(n = 48)
Health-related
30.1
33.3
Nonhealth-
69.9
66.7
Class majors
.17
.68b
.50c
c
.41
related (n = 141)
(n = 48)
Single
56.0
45.8
Dating
35.5
50.0
8.5
4.2
(n = 141)
(n = 48)
Yes
74.3
83.3
No
25.7
16.7
(n = 102)
(n = 40)
90.2
82.5
Men
4.9
12.5
Both
4.9
Age of first sex
M = 17.2(n = 99)
M = 16.8(n = 40)
.52a
(n = 54)
(n = 25)
1.00c
Relationship status
Married/Long-
.27b
term relationship Ever having sex
Partners Women
STI diagnosis
.16b
.28b
5.0
Yes
7.4
8.0
No
92.6
92.0
Note. M = mean, a = by independent t test, b = by chisquare test, c = by fisher’s exact test. *A number of responses (n) differ because the participants chose not to answer or inadvertently skipped the questions. Bold value = statistically significant value.
can cause anal cancer and can be transmitted via skin-to-skin contact (Table 2). Both groups had positive attitudes toward the vaccine. The overall mean score was 40.73 among nonvaccinees and 41.73 among vaccinees (on a possible range of 9–63). Specifically, both groups tended to have a neutral attitude toward calling the HPV vaccine an anticancer vaccine (M = 12.38 and 11.63, on a possible range of 3–21). Both groups had positive attitudes toward calling the vaccine an STI vaccine
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(M = 13.93 and 13.23) and toward mandating vaccination (M = 14.43 and 16.88), on a possible range of 3–21. Direct predictors. Nonvaccinees and vaccinees had positive attitudes toward getting vaccinated against HPV (M = 30.98 and 36.12, on a possible range of 6–42). The nonvaccinees had a slightly weak subjective norm (M = 14.48), while the vaccinees had a slightly stronger subjective norm (M = 16.83), on a possible range of 5–25 (Table 3). Both groups had strong perceived behavioral control (M = 17.22 and 15.90, on a possible range of 4–20).
Predictors of the HPV vaccination The indirect predictors (HPV/HPV vaccine knowledge and attitudes toward the vaccine) did not significantly correlate with the HPV vaccination, but the direct predictors (attitude toward getting vaccinated, subjective norms, and perceived behavioral control) did correlate (r = 0.26, 0.28, and 0.24, respectively). These variables and age were entered into a two-block hierarchical logistic regression model, using direct entry in both blocks—age was entered in the first block (for confounding control) and the three significant predictors were entered in the second block. After checking for the test assumptions, the Omnibus Test of Model Coefficients showed that when all four variables were considered together, the model was statistically significant (v2 = 42.41, df = 4, n = 189, p < 0.01). Approximately, between 20.1% (Cox & Snell R2) and 29.6% (Nagelkerke R2) of the variance in the HPV vaccination was accounted for by the four variables. Table 4 suggests that the odds of getting vaccinated increase when respondents are younger, have more positive attitudes toward getting vaccinated, and have less perceived behavioral control. Predictors of the vaccination intention among nonvaccinees Among nonvaccinees, the mean score for vaccination intention was 13.01 (SD = 4.19, 4–20). Some (38%) either agreed or strongly agreed with the statement “I intend to get vaccinated against HPV.” Approximately, 30% either agreed or strongly agreed with the statements “I have decided to get vaccinated against HPV” and “I plan to get vaccinated
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TABLE 2. HPV/HPV Vaccine Knowledge: Percentages of Correct Answers Knowledge statements
Nonvaccinees (n = 141), %
Vaccinees (n = 48), %
39.7 54.6 41.1 42.6
62.5 66.7 50.0 39.6
70.2 84.4 81.6
64.6 83.3 75.5
78.0 80.9
87.5 81.3
1. HPV is the most common sexually transmitted disease 2. HPV can cause genital warts 3. HPV can cause anal cancer 4. HPV can be transmitted via skin-to-skin contact (Penetration of the vagina or anus is not essential) 5. Most people with genital HPV have no visible signs or symptoms 6. Using a condom can provide partial protection against HPV 7. I can transmit HPV to my partner(s) even if I have no HPV symptoms 8. Only sexually active men should receive the HPV vaccine 9. HPV vaccine protects against all sexually transmitted infections
TABLE 3. Percentage of Participants Who either Agreed or Strongly Agreed with Subjective Norm Statements Subjective norm statements
Nonvaccinees (n = 141), %
Vaccinees (n = 48), %
24.9
58.3
28.3 9.9 62.4 8.6
54.2 2.1 83.3 27.1
Most people who are important to me think (thought) that I should get vaccinated against HPV It is (was) expected of me that I get (got) vaccinated against HPV I feel (felt) under social pressure to get vaccinated against HPV My doctor supports (supported) of my getting vaccinated against HPV Most men like me are vaccinated against HPV
TABLE 4. Logistic Regression Predicting HPV Vaccine Uptake (n = 189) Variables
B
SE
OR
p-value
Age Attitude: Getting Vaccinated Subjective Norm Perceived Behavioral Control
.24 .10 .09 .28
.08 .04 .07 .08
.79 1.11 1.10 .75
.004 .004 .14 .001
against HPV.” Close to 60% either agreed or strongly agreed with the statement “I expect to get vaccinated against HPV at some point.” Vaccination intention was not significantly related to any demographic, sexual history, HPV/ HPV vaccine knowledge, or perceived behavioral control. Vaccination intention was statistically significantly related to attitudes toward the vaccine, attitudes toward getting vaccinated against HPV, and subjective norms (r = 0.31, 0.67, and 0.66, respectively). The Mahalonobis Test indicated no outliers. Hence, all 141 nonvaccinees were included in the hierarchical multiple regression to determine the predictors of the vaccination intention. Based on Theory of Planned Behavior, the attitude toward the vaccine was controlled by being entered in the first block. The second block contained the attitude
toward getting vaccinated against HPV and the subjective norm. When the attitude toward the vaccine was entered alone, it significantly predicted the vaccination intention, F (1,139) = 15.22, p = .000, adjusted R2 = 0.09. When the significant direct predictors (the attitude toward getting vaccinated against HPV and the subjective norm) were added, the prediction model of the entire group was significantly improved, F (3, 137) = 64.11, p = 0.000, adjusted R2 = 0.58. However, the attitude toward the vaccine no longer contributed significantly to the model (Table 5).
Discussion As the HPV vaccine became available for U.S. boys/ men in 2009, this study is one of the few investigating the HPV vaccination rate in this group. Based on the current literature availability, this study is also the first to report the HPV vaccination rate and its related factors among young men in the United States (National Institutes of Health, 2014). Results showed HPV vaccination of 11.7% among universityattending men between 18 and 26 years of age— lower than the 34.6% of vaccination rate among
Ratanasiripong: Factors Related to HPV Vaccination in College Men
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TABLE 5. Hierarchical Multiple Regression Analysis Summary for Attitude toward Getting Vaccinated against HPV and Subjective Norm, Controlling for Attitudes toward HPV Vaccine, Predicting Intention to Obtain HPV Vaccine (n = 141) Variables Step 1 Attitudes: Vaccine Constant Step 2 Attitudes: Vaccine Attitude: Getting vaccinated Subjective norm Constant
B
SEB
b
R2
DR2
.12 8.11
.03 1.30
.31***
.09
.09
.03 .23 .48 .26
.03 .03 .08 1.11
.08 .49*** .42***
.58
.49
***p = .000.
adolescent boys in 2013 (Stokley et al., 2014). In the United States, gender-neutral vaccination is recommended (Stanley, 2014). However, the vaccination rate among young men was greatly lower when compared to the 47.3% of HPV vaccination rate among young college women in the same age range (Ratanasiripong, 2012). It is important to be reminded that the postlicensure vaccine safety monitoring since 2006 for females and 2009 for males has shown that the vaccine is considered safe (Stokley et al., 2014). Cost-effective analysis also showed that when the disease burden in males was included, male vaccination could be cost effective (depending on the vaccine coverage of females, vaccine cost, and the quality of life of those who are infected by HPV) (CDC, 2011c). Furthermore, while HPV infection may not manifest symptoms, the disease burden and prevalence rates are high in both genders (CDC, 2014b). While it is critical to promote HPV vaccination among females to decrease cervical cancer incidence rates, vigorous vaccination marketing campaigns should also target boys/young men so that anogenital cancer incidence rates can be effectively decreased across the genders. At the present moment, research on factors related to vaccination in males is sparse. The CDC commented that one of the reasons for the slowpace of vaccination could be the lack of clinician recommendations to the parents of boys and girls—over 50% of boys’ parents reported that the clinicians did not advise them about the HPV vaccination (Stokley et al., 2014). This study found that age was associated with the vaccination, with younger participants more likely to receive the vaccine than older participants. A few studies have noted an inconsistent association between age and the
vaccine uptake (Caskey, Lindau, & Alexander, 2009; Conroy et al., 2009; Rosenthal et al., 2011). Cautious interpretation must be made as these studies were conducted among college women. Interestingly, the findings of this study showed that both males who received and have not received the vaccine had a somewhat low level of knowledge related to the HPV/HPV vaccine. While many of them had general knowledge of HPV/HPV vaccine (e.g., no coverage for other STI, condom partial protection), they did not know about HPV-associated anogenital cancer and HPV transmission. Both groups had overall positive attitudes toward the HPV vaccine, including the idea to mandate the vaccination. As expected, HPV/HPV knowledge and attitudes toward the vaccine were not associated with the HPV vaccination. This finding was congruent with the previous study the researcher conducted among college females (Ratanasiripong et al., 2013). Based on the Theory of Planned Behavior, these variables may only indirectly be related to the vaccination. Thus, to increase the vaccination rate, the intervention programs should not focus on increasing knowledge or attitudes toward the vaccine itself. The study also found that young men in both groups had positive attitudes toward getting vaccinated against HPV—they believed that obtaining the vaccine would be beneficial, favorable, and useful. In addition, the nonvaccinees had a slightly weak subjective norm, whereas the vaccinees had a slightly strong subjective norm. Both groups reported that they did not feel under social pressure to get the vaccine, but they noted that they would obtain (or obtained) the vaccine if their doctor supported them in doing so. However, more than half
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of the vaccinees noted that they were expected to obtain the vaccine while the nonvaccinees noted that they were not. For perceived behavioral control, both groups had strong perceived behavioral control, but the nonvaccinees had stronger perception. In congruence with the theory’s assumptions, the positive correlations were found between the attitudes toward getting vaccinated against HPV, subjective norms, and the vaccination status. Unexpectedly, the vaccination status was negatively associated with perceived behavioral control. While there is no study reporting on the association of the three variables among male population, a similar result was found in the study conducted among college females (Ratanasiripong et al., 2013). When entering the three variables and age in the logistic regression model, the HPV vaccination status was predicted by younger age, positive attitude toward getting vaccinated against HPV, and less perceived behavioral control. Interventions to increase the vaccination rate may target the younger male population by increasing positive attitudes toward getting vaccinated against HPV. For the perceived behavioral control’s negative association with the vaccination, similarly commented on the previous finding among college women, the perceived behavioral control was measured after the respondents got the vaccine; their reality of the difficulty to obtain the vaccine might have taken into account and that might have lowered the perceived behavioral control (Ajzen, personal communication, March 28, 2012). In addition, perceived behavioral control might be lower among the vaccinees because they may have received the vaccine during their adolescent years when most health-related decisions were made by their parents. They might feel that getting vaccinated was beyond their control and was not entirely up to them to make the decision. Based on the Theory of Planned Behavior, intention is the immediate antecedent of behavior (HPV vaccination) (Ajzen, 1991). Among the nonvaccinees, the intention to obtain the vaccine was significantly positively associated with attitudes toward the vaccine, attitudes toward getting vaccinated against HPV, and subjective norms. Taking into account that each gender may be different in their attitudes and beliefs, this finding is similar to the previous findings. A handful of studies
conducted among young women also reported that vaccination intention can be predicted by normative belief (Kahn et al., 2008), social norms and subjective norms (Allen et al., 2009), perceived mother’s approval (Roberts, Gerrand, Reimer, & Gibbons, 2010), and attitude toward vaccination (Holguin, 2009). However, when the indirect and director predictors were entered in the prediction model, using hierarchical multiple regression, only attitudes toward getting vaccinated against HPV and subjective norms could significantly predict the intention to obtain the vaccine. The finding supported the assumptions of the theory that the attitude toward the vaccine (indirect predictor) was mediated by the direct predictors. The finding was also supported by the previous study, conducted among college women in 2012, which found the same variables as the predictors of the intention (Ratanasiripong, 2012). The result suggested that intervention to increase the vaccination intention may be done through increasing attitude toward getting vaccinated against HPV and subjective norm. According to the theory (Ajzen, 2010), intervention designed to change the vaccination can be directed at one or more predictors. The intervention should attempt to change the salient beliefs. For example, to enhance positive attitudes toward getting vaccinated against HPV, the intervention should focus on behavioral beliefs (e.g., having an anogenital cancer is negative and getting the vaccine can positively help prevent such serious condition, HPV causes genital warts and getting the vaccine can prevent the HPV infection that causes genital warts). To enhance subjective norms through normative beliefs, the intervention can also target the significant others of the young men (e.g., parents) and health care providers who then would advise young men to obtain the vaccine. While various methods were used to minimize potential threats to research validity, the findings should be interpreted within known limitations including the following: (1) generalizability may be limited due to a convenience sample of college males from one university; (2) reporting biases may be present among respondents with strong feelings about the HPV/HPV vaccine; (3) a recalling bias may occur due to the retrospective reports on certain variables; and (4) a nonresponse bias may be present due to the low response rate.
Ratanasiripong: Factors Related to HPV Vaccination in College Men In conclusion, this research offers new information regarding the vaccine uptake and factors influencing the vaccination rate among college men. The findings suggest that college men have low knowledge on HPV/HPV vaccine, positive attitudes toward the vaccine and toward getting vaccinated against HPV. They also believe that they would obtain the vaccine if the health care providers support/recommend them. Both vaccination status and intention to obtain the vaccine can be predicted by the attitude toward getting vaccinated against HPV. The intention can also be predicated by the subjective norm. Hence, intervention to increase HPV vaccination rates should be performed by enhancing behavioral beliefs, which will increase the positive attitude toward getting vaccinated against HPV. The intervention may also target the health care provider and/or parent populations. Mandating the vaccine with an opt-out option may be a proper strategy as college men also have positive attitudes toward mandating the vaccine. Future research may include testing an intervention program (focusing on attitudes and subjective norms) to improve the HPV vaccination rate among young men so that HPV infection can be reduced across the genders.
Acknowledgements This study was funded by California State University, Dominguez Hills (Research, Scholarly, and Creative Activity Awards Program). The author is solely responsible for study design, implementation, analysis, interpretation, and report.
References Ajzen, I. (1991). The theory of planned behavior. Organizational Behavior and Human Decision Processes, 50, 179–211. Ajzen, I. (2010). Behavioral interventions based on Theory of Planned Behavior. Retrieved from http://people.umas s.edu/aizen/pdf/tpb.intervention.pdf Ajzen, I., & Fishbein, M. (2005). The influence of attitudes on behavior. Retrieved from http://apollo.psico.unimib.it/ shared/psychoscope/site/reference_pap/AF_Chap2005.pdf Allen, J. D., Mohllajee, A. P., Shelton, R. C., Othus, M. K., Fontenot, H. B., & Hanna, R. (2009). Stage of adoption of the Human Papillomavirus vaccine among college women. Preventive Medicine, 48, 420–425. Caskey, R., Lindau, S. T., & Alexander, G. C. (2009). Knowledge and early adoption of the HPV vaccine among girls and young women: Results of a national survey. Journal of Adolescent Health, 45(1), 453–462. Centers for Disease Control and Prevention. (2011a). Sexually transmitted diseases (STDs): HPV and men-fact sheet. Retrieved from http://www.cdc.gov/std/hpv/stdfact-hpv-and-men.htm Centers for Disease Control and Prevention. (2011b). Statistics and surveillance: 2009 adult vaccination coverage, NHIS.
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Retrieved from http://www.cdc.gov/vaccines/stats-surv/ nhis/2009-nhis.htm Centers for Disease Control and Prevention. (2011c). Recommendations on the use of Quadrivalent Human Papillomavirus vaccine in males — Advisory Committee on Immunization Practices (ACIP), 2011. Retrieved from http://www.cdc.gov/ mmwr/preview/mmwrhtml/mm6050a3.htm Centers for Disease Control and Prevention. (2013). HPV vaccines. Retrieved from http://www.cdc.gov/hpv/vaccine.html Centers for Disease Control and Prevention. (2014a). Human Papillomavirus (HPV)-associated cancers. Retrieved from http:// www.cdc.gov/cancer/hpv/ Centers for Disease Control and Prevention. (2014b). Human Papillomavirus (HPV). Retrieved from http://www.cdc.gov/std/hpv/ Conroy, K., Rosenthal, S. L., Zimet, G. D., Jin, Y., Bernstein, D. I., Glynn, S., et al. (2009). Human Papillomavirus vaccine uptake, predictors of vaccination, and self-reported barriers to vaccination. Journal of Women’s Health, 18(10), 1679– 1686. Dunne, E. F., Nielson, C. M., Stone, K. M., Markowitz, L. E., & Giuliano, A. R. (2006). Prevalence of HPV infection among men: A systemic review of the literature. Journal of Infectious Diseases, 194, 1004–1057. Faul, F., Erdfelder, E., Buchner, A., & Lang, A. G. (2009). Statistics power analyses using G*Power 3.1: Test for correlation and regression analysis. Behavior Research Methods, 41(4), 1149–1160. Frazer, I. H., Cox, J. T., Mayeaux, E. J., Franco, E. L., Moscicki, A. B., Palefsky, J. M., et al. (2006). Advances in prevention of cervical cancer and other Human Papillomavirus-related diseases. The Pediatric Infectious Disease Journal, 25(2), S65–S81. Holguin, A. C. (2009). Determining the knowledge and attitudes of 18- to 26-year old women regarding cervical cancer, Human Papillomavirus, and the Human Papillomavirus vaccine. Master’s Thesis, Utah State University. Retrieved from http://digitalcommons.usu.edu/etd/464/ Kahn, J. A., Rosenthal, S. L., Jin, Y., Huang, B., Namakydoust, A., & Zimet, G. D. (2008). Rates of Human Papillomavirus vaccination, attitudes about vaccination, and Human Papillomavirus prevalence in young women. Obstetrics and Gynecology, 111(5), 1103–1110. Markowitz, L. E., Dunne, E., Saraiya, M., Chesson, H. W., Robinette Curtis, C., Gee, J., et al. (2014). Human Papillomavirus vaccination: Recommendations of the Advisory Committee on Immunization Practices (ACIP). Center of Disease Control and Prevention. Retrieved from http://www.cdc.gov/ mmwr/preview/mmwrhtml/rr6305a1.htm National Institutes of Health. (2014). PubMed. National Library of Medicine. Retrieved from http://www.ncbi.nlm.nih.gov/ pubmed Radhakrishnan, B. (2006). “Major Breakthrough”: FDA approves cervical cancer vaccine. ABC News. Retrieved from http:// abcnews.go.com/Health/WomensHealth/story?id=2054043 &page=1 Ratanasiripong, N. (2012). What college women know, think, and do about Human Papillomavirus (HPV) and HPV vaccine (Doctoral dissertation). Kansas City, MO: University of Missouri. Ratanasiripong, N., Cheng, A. L., & Enriquez, M. (2013). What college women know, think, and do about Human Papillomavirus (HPV) and HPV vaccine. The Vaccine, 31(10), 3170–3176. Roberts, M. E., Gerrand, M., Reimer, R., & Gibbons, F. X. (2010). Mother-daughter communication and Human Papillomavirus vaccine update by college students. Pediatrics, 125(5), 982–989. Rosenthal, S. L., Weiss, T. W., Zimet, G. D., Ma, L., Good, M. B., & Vichnin, M. D. (2011). Predictors of HPV vaccine uptake among women aged 19-26: Importance of a physician’s recommendation. Vaccine, 29(5), 890–895.
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Satterwhite, C. L., Torrone, E., Meites, E., Dunne, E. F., Mahajan, R., Ocfemia, M. C., et al. (2013). Sexually transmitted infections among US women and men: Prevalence and incidence estimates, 2008. Sexual Transmitted Diseases, 40(3), 187–193. Stanley, M. (2010). Pathology and epidemiology of HPV infection in females. Gynecological Oncology, 117, S5–S10. Stanley, M. (2014). HPV vaccination in boys and men. Human Vaccines & Immunotherapeutics, 10(7), 1. Stokley, S., Jeyarajah, J., Yankey, D., Cano, M., Gee, J., Roark, J., et al. (2014). Human Papillomavirus vaccination coverage
among adolescents, 2007–2013, and postlicensure vaccine safety monitoring, 2006–2014-United States. Center of Disease Control and Prevention. Retrieved from http:// www.cdc.gov/mmwr/preview/mmwrhtml/mm6329a3.htm Winer, R. L., Hughes, J. P., Feng, Q., O’Reilly, S., Kiviat, N. B., Holmes, K. K., et al. (2006). Condom use and the risk of genital Human Papillomavirus infection in young women. New England Journal of Medicine, 354, 2645–2654.
POPULATIONS
AT
RISK ACROSS
THE
LIFESPAN: POPULATION STUDIES
Factors Related to Human Papillomavirus (HPV) Vaccination in College Men Nop Thodsama Ratanasiripong, Ph.D, R.N, C.C.R.C School of Nursing, California State University, Dominguez Hills, Carson, California Correspondence to: Nop Thodsama Ratanasiripong, School of Nursing, California State University, Dominguez Hills, 1100 E. Victoria St., Carson, CA 90747. E-mail: [email protected]
ABSTRACT Objectives: To examine the vaccination rate and identify factors influencing HPV vaccination among college men. Design and Sample: This cross-sectional study, guided by Theory of Planned Behavior, was conducted with a convenience sample of college males (18–26 years of age). A web-based survey was sent to 3,300 students attending a public university in California. Measures: The questionnaire used in the study—HPV/HPV vaccine-related Knowledge, Attitudes, and Behaviors—was adapted from a prior study conducted among college women. Demographic and sexual history information was also obtained. Results: Four hundred and ten respondents were qualified for analysis. HPV vaccination rate was approximately 11.8%. Overall, young men had quite low HPV/HPV vaccine knowledge. Both nonvaccinees (n = 48) and vaccinees (n = 141) had positive attitudes toward the HPV vaccine, including mandating vaccination. Knowledge and attitudes toward the vaccine were not directly associated with the outcomes of vaccination status and intention. Both outcomes could be predicted by the attitude toward getting vaccinated against HPV. Intention was also predicted by subjective norm. Conclusion: Interventions to increase the vaccination rate should focus on creating positive attitude toward getting vaccinated against HPV through behavioral beliefs. Increasing the subjective norm will be beneficial. Key words: Human Papillomavirus, vaccination, men.
Background Human Papillomavirus (HPV) is responsible for most of both incident and prevalent sexually transmitted infections (STIs) in the United States (Satterwhite et al., 2013). Approximately, 14 million Americans aged 15–59 years are newly diagnosed with HPV each year and half of them are young adults aged 15–24 years (Markowitz et al., 2014). Similar to females, the prevalence of genital HPV infection is estimated to be at least 20% in the male population (Dunne, Nielson, Stone, Markowitz, & Giuliano, 2006). In the United States, 20,000 women and 12,000 men are diagnosed with HPV-related cancers each year (Centers for Disease Control and Prevention [CDC], 2014a). Specifically,
men who have sex with men (MSM) are 17 times more likely to develop HPV-related anal cancer than heterosexual men (CDC, 2011a). While most HPV infections (70–90%) may clear by themselves in 3 years, HPV can also cause genital warts and anogenital cancers (e.g., cervical, vaginal, anal, and penile cancers) (Frazer et al., 2006). HPV infection and anogenital cancer morbidity not only result in emotional and physical distress at the individual level but also result in increased health care costs. Currently, HPV is the second most expensive STI, following HIV. In the United States, 1 to 6 billion dollars are annually exhausted for cervical/anal cancer screening and treatments (Frazer et al., 2006).
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The primary route of genital HPV infection is sexual intercourse, both vaginal and anal. HPV transmission occurs via skin-to-skin contact, but penetration of the vagina or anus is not essential (Stanley, 2010). Regular and consistent use of condoms offers only partial protection (60%) against HPV infection (Winer et al., 2006). Because most HPV-infected persons do not show obvious signs or symptoms, it has been challenging to develop HPV detection and prevention programs. The opportunity for HPV prevention was presented with the licensing of an HPV vaccine in the United States. The HPV vaccine (Gardasil) was first approved for females aged 9–26 in 2006 and for males aged 9–26 in 2009 (CDC, 2013). Despite the vaccine being considered a medical breakthrough (Radhakrishnan, 2006), national data show considerably low HPV vaccination rates. For adolescents aged 13–17, 44.3% have received at least one dose and 26.7% have received three doses of the HPV vaccine. For young women aged 19–26, only 17.1% have received at least one dose of the HPV vaccine (CDC, 2011b). Because of such results, a variety of HPV vaccine promotion and research studies have been done in attempt to increase the HPV vaccination rate among women. For young men, HPV vaccine related-research is sparse. The vaccination rate among boys/men is currently unknown, as is an understanding about what influences on college men’s decision to obtain the HPV vaccine. This information can provide the basis for HPV prevention and vaccination programs for all genders. This cross-sectional study used a theory-driven approach to: (1) examine the vaccination rate and (2) identify factors influencing HPV vaccination among college men. The Theory of Planned Behav-
Figure 1. The Study Theoretical Framework
ior guided the study and provided a framework for understanding the factors associated with vaccination and vaccination intention. The study’s theoretical framework is illustrated in Figure 1. The Theory posits that a person’s behavior (i.e., getting vaccinated against HPV) is determined by the intention to perform such behavior. Intention is influenced by the attitude toward the behavior, subjective norm, and perceived behavioral control (Ajzen, 1991). Variables such as demographic characteristics, past behavioral experiences, knowledge, and attitude toward an object are considered as indirect factors that may impact the intention and behavior through attitude toward the behavior, subjective norm, and perceived behavioral control (Ajzen, 1991). The attitude toward an object (e.g., hamburger, vaccine, and ethnicity) is considered to be general and broad. This type of attitude is only remotely linked to intention and the behavior in question. The attitude toward a behavior is the attitude toward performing the specific behavior with respect to an object/target (e.g., eating a hamburger, getting vaccinated against HPV, hiring an Asian-American). This type of attitude is directly linked to the intention and behavior (Ajzen & Fishbein, 2005). Subjective norm is one’s perception of what significant others expect of him/her. Perceived behavioral control is one’s confidence to perform a behavior in question (Ajzen, 1991).
Methods Design and sample Setting and population. This cross-sectional study was conducted with a convenience sample of college men ages 18–26 attending a public university
Ratanasiripong: Factors Related to HPV Vaccination in College Men in southern California. The maximum age range was consistent with the 26 years of age limit to be vaccinated against HPV. Sample size. Based on regression analysis and the following parameters—a power of 0.9, with small effect size (0.1), alpha equals 0.05, and three direct predictors (attitude toward getting vaccinated, subjective norms, perceived behavioral control)—a minimum of 159 subjects was needed (Faul, Erdfelder, Buchner, & Lang, 2009). Procedures for data collection. After Institutional Review Board’s approval, 3,300 random e-mail addresses of male students were obtained from the university. An invitation was emailed to the potential research subjects in which students were directed to click on a web-based survey link (SurveyMonkey) if they wished to participate in the study. After reading the informed consent page, the students who agreed to participate completed the survey. To enhance the response rate, an e-mail reminder was sent to the students 1 and 2 weeks after the first invitation. Students who did not wish to receive reminders could request their e-mail addresses be taken off the list. A prize strategy was also applied as an incentive. The respondents had the opportunity to draw a prize, if they were one of the first 210 respondents who completed the survey and emailed the researcher to request a prize drawing (four $100, six $ 50, and 200 $10 gift cards). The researcher drew the prize and mailed the gift cards to the respondents unless they wished to pick it up on campus. The web-based survey was deactivated 1 month after the invitation was sent out. To provide anonymity for the respondents, the IP address tracking function on SurveyMonkey was disabled.
Measures The questionnaire used in this research—HPV and HPV vaccine-related Knowledge, Attitudes, and Behaviors—was adapted from the researcher’s prior study conducted among college women (Ratanasiripong, Cheng, & Enriquez, 2013). The questionnaire was developed using constructs of the Theory of Planned Behaviors and was reviewed for face and content validity. Reliability from the prior study data indicated the Cronbach’s coefficient alphas of all scales (attitudes, subjective norms, perceived
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behavioral control, and vaccination intention) were between 0.71 and 0.93 (Ratanasiripong et al., 2013). The questionnaire included (1) nine items to measure HPV/HPV vaccine knowledge (true/false); (2) nine items to measure attitudes toward the HPV vaccine (semantic differential scale); (3) six items to measure attitudes toward getting vaccinated against HPV (semantic differential scale)— for nonvaccinees (subjects who have not obtained the vaccine), the statement of attitude was “my getting vaccinated against HPV would be. . .”; for vaccinees (subjects who have obtained the vaccine), the statement of attitude was “I thought that my getting vaccinated against HPV would be. . .”; (4) five items to measure subjective norms (Likert scale)—the present tense was used in the statements for nonvaccinees, while the past tense was used in the statement for vaccinees (e.g., “I feel under social pressure to get vaccinated against HPV” vs. “I felt under social pressure to get vaccinated against HPV”); (5) four items to measure perceived behavioral control (Likert scale)—the present tense was used in the statements for nonvaccinees, while the past tense was used in the statement for vaccinees; and (6) four items to measure vaccination intention (Likert scale) among nonvaccinees only. Vaccination intention was measured only among the male respondents who have not received the vaccine. In addition to the questionnaire items, the survey asked about vaccination status, demographic, sexual history, and sexual experiences. Cronbach’s coefficient alphas of all scales remained in the range of 0.69–0.95.
Analytic strategy The study data were analyzed using SPSS 20.0. Descriptive statistics were used to describe demographics, sexual history, and vaccination status. Depending on the variables’ level of measurement, independent t test and chi-square tests were used to determine the differences in the demographic and sexual history variables between those who have obtained the vaccine and those who have not. Pearson’s or Spearman’s correlation coefficients were used to determine the relationships between the respondent characteristics, indirect predictors (HPV knowledge, attitudes toward the vaccine), direct predictors (attitudes toward getting vaccinated against HPV, subjective norm, and perceived behavioral
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control), and the outcome variables—intention to obtain the vaccine and vaccination status. Two separate regression analyses were used to determine the relative contribution of the predictor variables to the outcome variables. For the vaccination status, hierarchical logistic regression was conducted by controlling a significant demographic (age). For the vaccination intention, hierarchical multiple regression was conducted by controlling a significant indirect predictor (attitudes toward the vaccine).
Results Out of 3,300 students, 451 agreed to participate, for a response rate of 13.7%. Among these, 41 were not qualified because more than 20% of items were missing or they failed on attention-testing items (which indicated if the respondents paid attention to answer the questions). Among the 410 qualified respondents, 210 (51.2%) were aware of the HPV and HPV vaccine. Of 210 respondents, 48 (22.9%) received at least one dose of the HPV vaccine (vaccinees), 141 (67.1%) had not obtained the vaccine (nonvaccinees), and 21 (10%) preferred not to answer, making 189 respondents available for further analysis (Fig. 2). In assuming that those who were unaware of the HPV/HPV vaccine had not received the vaccine, the vaccination rate was approximately 11.7% (48 out of 410 respondents).
Sample characteristics Demographic. As shown in Table 1, age was the only variable that was significantly associated with the vaccine status (p = .002). More than half of the participants in both groups (nonvaccinees and vaccinees) were Latinos (50.7% and 60.4%, respectively). Similarly, more than half in both groups reported that they were Christian (e.g., Protestant, Catholic, nondenomination). Close to 75% of both groups noted that they had health insurance and that they were in nonhealth-related majors. Sexual history. As shown in Table 1, both nonvaccinee and vaccinee groups shared similar sexual history. The majority of them were either single or dating. Over 75% of both groups reported having had sexual intercourse and the majority of them had sex with women. With the nonvaccinee group, the average age of first sexual intercourse
Figure 2. Summary of the Number of Responses was 17.2, and within the vaccinee group, the average age of first sexual intercourse was 16.85. The difference of age of first sexual intercourse was not statistically significant (p = .52). Over 90% of participants who had had sexual intercourse had never been diagnosed with a STI.
Description of the variables Indirect predictors. Of 9 points, the mean score of HPV/HPV vaccine knowledge among nonvaccinees was 5.73 (SD = 2.23) and among vaccinees was 6.10 (SD = 2.36). The difference of the knowledge mean scores between the two groups was not statistically significant, t (187) = 0.99, p = .33. Most respondents (over 75%) in both groups knew that condoms provided partial protection against HPV, that transmission of HPV can occur during the asymptomatic period, that not only sexually active men should receive the HPV vaccine, and that the HPV vaccine does not protect against other STIs. On the opposite end of the spectrum, less than or about half knew that HPV
Ratanasiripong: Factors Related to HPV Vaccination in College Men TABLE 1. Demographic Characteristics and Sexual History of Respondents* Nonvaccinees
Age Ethnicity Caucasian
Vaccinees
(%)
(%)
p-value
M = 22.4(n = 128)
M = 21.0(n = 43)
.002a
(n = 138)
(n = 48)
b
13.8
6.3
Asian
18.1
8.3
Latino
50.7
60.4
Black
9.4
16.7
Other
7.9
Religion Christianity
8.4
(n = 138)
(n = 48)
55.1
62.5
Other
18.8
14.6
None
26.1
22.9
(n = 138)
(n = 48)
Yes
65.2
66.7
No
34.8
33.3
Insurance status
(n = 136)
(n = 48)
Health-related
30.1
33.3
Nonhealth-
69.9
66.7
Class majors
.17
.68b
.50c
c
.41
related (n = 141)
(n = 48)
Single
56.0
45.8
Dating
35.5
50.0
8.5
4.2
(n = 141)
(n = 48)
Yes
74.3
83.3
No
25.7
16.7
(n = 102)
(n = 40)
90.2
82.5
Men
4.9
12.5
Both
4.9
Age of first sex
M = 17.2(n = 99)
M = 16.8(n = 40)
.52a
(n = 54)
(n = 25)
1.00c
Relationship status
Married/Long-
.27b
term relationship Ever having sex
Partners Women
STI diagnosis
.16b
.28b
5.0
Yes
7.4
8.0
No
92.6
92.0
Note. M = mean, a = by independent t test, b = by chisquare test, c = by fisher’s exact test. *A number of responses (n) differ because the participants chose not to answer or inadvertently skipped the questions. Bold value = statistically significant value.
can cause anal cancer and can be transmitted via skin-to-skin contact (Table 2). Both groups had positive attitudes toward the vaccine. The overall mean score was 40.73 among nonvaccinees and 41.73 among vaccinees (on a possible range of 9–63). Specifically, both groups tended to have a neutral attitude toward calling the HPV vaccine an anticancer vaccine (M = 12.38 and 11.63, on a possible range of 3–21). Both groups had positive attitudes toward calling the vaccine an STI vaccine
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(M = 13.93 and 13.23) and toward mandating vaccination (M = 14.43 and 16.88), on a possible range of 3–21. Direct predictors. Nonvaccinees and vaccinees had positive attitudes toward getting vaccinated against HPV (M = 30.98 and 36.12, on a possible range of 6–42). The nonvaccinees had a slightly weak subjective norm (M = 14.48), while the vaccinees had a slightly stronger subjective norm (M = 16.83), on a possible range of 5–25 (Table 3). Both groups had strong perceived behavioral control (M = 17.22 and 15.90, on a possible range of 4–20).
Predictors of the HPV vaccination The indirect predictors (HPV/HPV vaccine knowledge and attitudes toward the vaccine) did not significantly correlate with the HPV vaccination, but the direct predictors (attitude toward getting vaccinated, subjective norms, and perceived behavioral control) did correlate (r = 0.26, 0.28, and 0.24, respectively). These variables and age were entered into a two-block hierarchical logistic regression model, using direct entry in both blocks—age was entered in the first block (for confounding control) and the three significant predictors were entered in the second block. After checking for the test assumptions, the Omnibus Test of Model Coefficients showed that when all four variables were considered together, the model was statistically significant (v2 = 42.41, df = 4, n = 189, p < 0.01). Approximately, between 20.1% (Cox & Snell R2) and 29.6% (Nagelkerke R2) of the variance in the HPV vaccination was accounted for by the four variables. Table 4 suggests that the odds of getting vaccinated increase when respondents are younger, have more positive attitudes toward getting vaccinated, and have less perceived behavioral control. Predictors of the vaccination intention among nonvaccinees Among nonvaccinees, the mean score for vaccination intention was 13.01 (SD = 4.19, 4–20). Some (38%) either agreed or strongly agreed with the statement “I intend to get vaccinated against HPV.” Approximately, 30% either agreed or strongly agreed with the statements “I have decided to get vaccinated against HPV” and “I plan to get vaccinated
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TABLE 2. HPV/HPV Vaccine Knowledge: Percentages of Correct Answers Knowledge statements
Nonvaccinees (n = 141), %
Vaccinees (n = 48), %
39.7 54.6 41.1 42.6
62.5 66.7 50.0 39.6
70.2 84.4 81.6
64.6 83.3 75.5
78.0 80.9
87.5 81.3
1. HPV is the most common sexually transmitted disease 2. HPV can cause genital warts 3. HPV can cause anal cancer 4. HPV can be transmitted via skin-to-skin contact (Penetration of the vagina or anus is not essential) 5. Most people with genital HPV have no visible signs or symptoms 6. Using a condom can provide partial protection against HPV 7. I can transmit HPV to my partner(s) even if I have no HPV symptoms 8. Only sexually active men should receive the HPV vaccine 9. HPV vaccine protects against all sexually transmitted infections
TABLE 3. Percentage of Participants Who either Agreed or Strongly Agreed with Subjective Norm Statements Subjective norm statements
Nonvaccinees (n = 141), %
Vaccinees (n = 48), %
24.9
58.3
28.3 9.9 62.4 8.6
54.2 2.1 83.3 27.1
Most people who are important to me think (thought) that I should get vaccinated against HPV It is (was) expected of me that I get (got) vaccinated against HPV I feel (felt) under social pressure to get vaccinated against HPV My doctor supports (supported) of my getting vaccinated against HPV Most men like me are vaccinated against HPV
TABLE 4. Logistic Regression Predicting HPV Vaccine Uptake (n = 189) Variables
B
SE
OR
p-value
Age Attitude: Getting Vaccinated Subjective Norm Perceived Behavioral Control
.24 .10 .09 .28
.08 .04 .07 .08
.79 1.11 1.10 .75
.004 .004 .14 .001
against HPV.” Close to 60% either agreed or strongly agreed with the statement “I expect to get vaccinated against HPV at some point.” Vaccination intention was not significantly related to any demographic, sexual history, HPV/ HPV vaccine knowledge, or perceived behavioral control. Vaccination intention was statistically significantly related to attitudes toward the vaccine, attitudes toward getting vaccinated against HPV, and subjective norms (r = 0.31, 0.67, and 0.66, respectively). The Mahalonobis Test indicated no outliers. Hence, all 141 nonvaccinees were included in the hierarchical multiple regression to determine the predictors of the vaccination intention. Based on Theory of Planned Behavior, the attitude toward the vaccine was controlled by being entered in the first block. The second block contained the attitude
toward getting vaccinated against HPV and the subjective norm. When the attitude toward the vaccine was entered alone, it significantly predicted the vaccination intention, F (1,139) = 15.22, p = .000, adjusted R2 = 0.09. When the significant direct predictors (the attitude toward getting vaccinated against HPV and the subjective norm) were added, the prediction model of the entire group was significantly improved, F (3, 137) = 64.11, p = 0.000, adjusted R2 = 0.58. However, the attitude toward the vaccine no longer contributed significantly to the model (Table 5).
Discussion As the HPV vaccine became available for U.S. boys/ men in 2009, this study is one of the few investigating the HPV vaccination rate in this group. Based on the current literature availability, this study is also the first to report the HPV vaccination rate and its related factors among young men in the United States (National Institutes of Health, 2014). Results showed HPV vaccination of 11.7% among universityattending men between 18 and 26 years of age— lower than the 34.6% of vaccination rate among
Ratanasiripong: Factors Related to HPV Vaccination in College Men
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TABLE 5. Hierarchical Multiple Regression Analysis Summary for Attitude toward Getting Vaccinated against HPV and Subjective Norm, Controlling for Attitudes toward HPV Vaccine, Predicting Intention to Obtain HPV Vaccine (n = 141) Variables Step 1 Attitudes: Vaccine Constant Step 2 Attitudes: Vaccine Attitude: Getting vaccinated Subjective norm Constant
B
SEB
b
R2
DR2
.12 8.11
.03 1.30
.31***
.09
.09
.03 .23 .48 .26
.03 .03 .08 1.11
.08 .49*** .42***
.58
.49
***p = .000.
adolescent boys in 2013 (Stokley et al., 2014). In the United States, gender-neutral vaccination is recommended (Stanley, 2014). However, the vaccination rate among young men was greatly lower when compared to the 47.3% of HPV vaccination rate among young college women in the same age range (Ratanasiripong, 2012). It is important to be reminded that the postlicensure vaccine safety monitoring since 2006 for females and 2009 for males has shown that the vaccine is considered safe (Stokley et al., 2014). Cost-effective analysis also showed that when the disease burden in males was included, male vaccination could be cost effective (depending on the vaccine coverage of females, vaccine cost, and the quality of life of those who are infected by HPV) (CDC, 2011c). Furthermore, while HPV infection may not manifest symptoms, the disease burden and prevalence rates are high in both genders (CDC, 2014b). While it is critical to promote HPV vaccination among females to decrease cervical cancer incidence rates, vigorous vaccination marketing campaigns should also target boys/young men so that anogenital cancer incidence rates can be effectively decreased across the genders. At the present moment, research on factors related to vaccination in males is sparse. The CDC commented that one of the reasons for the slowpace of vaccination could be the lack of clinician recommendations to the parents of boys and girls—over 50% of boys’ parents reported that the clinicians did not advise them about the HPV vaccination (Stokley et al., 2014). This study found that age was associated with the vaccination, with younger participants more likely to receive the vaccine than older participants. A few studies have noted an inconsistent association between age and the
vaccine uptake (Caskey, Lindau, & Alexander, 2009; Conroy et al., 2009; Rosenthal et al., 2011). Cautious interpretation must be made as these studies were conducted among college women. Interestingly, the findings of this study showed that both males who received and have not received the vaccine had a somewhat low level of knowledge related to the HPV/HPV vaccine. While many of them had general knowledge of HPV/HPV vaccine (e.g., no coverage for other STI, condom partial protection), they did not know about HPV-associated anogenital cancer and HPV transmission. Both groups had overall positive attitudes toward the HPV vaccine, including the idea to mandate the vaccination. As expected, HPV/HPV knowledge and attitudes toward the vaccine were not associated with the HPV vaccination. This finding was congruent with the previous study the researcher conducted among college females (Ratanasiripong et al., 2013). Based on the Theory of Planned Behavior, these variables may only indirectly be related to the vaccination. Thus, to increase the vaccination rate, the intervention programs should not focus on increasing knowledge or attitudes toward the vaccine itself. The study also found that young men in both groups had positive attitudes toward getting vaccinated against HPV—they believed that obtaining the vaccine would be beneficial, favorable, and useful. In addition, the nonvaccinees had a slightly weak subjective norm, whereas the vaccinees had a slightly strong subjective norm. Both groups reported that they did not feel under social pressure to get the vaccine, but they noted that they would obtain (or obtained) the vaccine if their doctor supported them in doing so. However, more than half
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of the vaccinees noted that they were expected to obtain the vaccine while the nonvaccinees noted that they were not. For perceived behavioral control, both groups had strong perceived behavioral control, but the nonvaccinees had stronger perception. In congruence with the theory’s assumptions, the positive correlations were found between the attitudes toward getting vaccinated against HPV, subjective norms, and the vaccination status. Unexpectedly, the vaccination status was negatively associated with perceived behavioral control. While there is no study reporting on the association of the three variables among male population, a similar result was found in the study conducted among college females (Ratanasiripong et al., 2013). When entering the three variables and age in the logistic regression model, the HPV vaccination status was predicted by younger age, positive attitude toward getting vaccinated against HPV, and less perceived behavioral control. Interventions to increase the vaccination rate may target the younger male population by increasing positive attitudes toward getting vaccinated against HPV. For the perceived behavioral control’s negative association with the vaccination, similarly commented on the previous finding among college women, the perceived behavioral control was measured after the respondents got the vaccine; their reality of the difficulty to obtain the vaccine might have taken into account and that might have lowered the perceived behavioral control (Ajzen, personal communication, March 28, 2012). In addition, perceived behavioral control might be lower among the vaccinees because they may have received the vaccine during their adolescent years when most health-related decisions were made by their parents. They might feel that getting vaccinated was beyond their control and was not entirely up to them to make the decision. Based on the Theory of Planned Behavior, intention is the immediate antecedent of behavior (HPV vaccination) (Ajzen, 1991). Among the nonvaccinees, the intention to obtain the vaccine was significantly positively associated with attitudes toward the vaccine, attitudes toward getting vaccinated against HPV, and subjective norms. Taking into account that each gender may be different in their attitudes and beliefs, this finding is similar to the previous findings. A handful of studies
conducted among young women also reported that vaccination intention can be predicted by normative belief (Kahn et al., 2008), social norms and subjective norms (Allen et al., 2009), perceived mother’s approval (Roberts, Gerrand, Reimer, & Gibbons, 2010), and attitude toward vaccination (Holguin, 2009). However, when the indirect and director predictors were entered in the prediction model, using hierarchical multiple regression, only attitudes toward getting vaccinated against HPV and subjective norms could significantly predict the intention to obtain the vaccine. The finding supported the assumptions of the theory that the attitude toward the vaccine (indirect predictor) was mediated by the direct predictors. The finding was also supported by the previous study, conducted among college women in 2012, which found the same variables as the predictors of the intention (Ratanasiripong, 2012). The result suggested that intervention to increase the vaccination intention may be done through increasing attitude toward getting vaccinated against HPV and subjective norm. According to the theory (Ajzen, 2010), intervention designed to change the vaccination can be directed at one or more predictors. The intervention should attempt to change the salient beliefs. For example, to enhance positive attitudes toward getting vaccinated against HPV, the intervention should focus on behavioral beliefs (e.g., having an anogenital cancer is negative and getting the vaccine can positively help prevent such serious condition, HPV causes genital warts and getting the vaccine can prevent the HPV infection that causes genital warts). To enhance subjective norms through normative beliefs, the intervention can also target the significant others of the young men (e.g., parents) and health care providers who then would advise young men to obtain the vaccine. While various methods were used to minimize potential threats to research validity, the findings should be interpreted within known limitations including the following: (1) generalizability may be limited due to a convenience sample of college males from one university; (2) reporting biases may be present among respondents with strong feelings about the HPV/HPV vaccine; (3) a recalling bias may occur due to the retrospective reports on certain variables; and (4) a nonresponse bias may be present due to the low response rate.
Ratanasiripong: Factors Related to HPV Vaccination in College Men In conclusion, this research offers new information regarding the vaccine uptake and factors influencing the vaccination rate among college men. The findings suggest that college men have low knowledge on HPV/HPV vaccine, positive attitudes toward the vaccine and toward getting vaccinated against HPV. They also believe that they would obtain the vaccine if the health care providers support/recommend them. Both vaccination status and intention to obtain the vaccine can be predicted by the attitude toward getting vaccinated against HPV. The intention can also be predicated by the subjective norm. Hence, intervention to increase HPV vaccination rates should be performed by enhancing behavioral beliefs, which will increase the positive attitude toward getting vaccinated against HPV. The intervention may also target the health care provider and/or parent populations. Mandating the vaccine with an opt-out option may be a proper strategy as college men also have positive attitudes toward mandating the vaccine. Future research may include testing an intervention program (focusing on attitudes and subjective norms) to improve the HPV vaccination rate among young men so that HPV infection can be reduced across the genders.
Acknowledgements This study was funded by California State University, Dominguez Hills (Research, Scholarly, and Creative Activity Awards Program). The author is solely responsible for study design, implementation, analysis, interpretation, and report.
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