Published on 01.09.14 in Vol 16, No 9 (2014): September
Estimation of Geographic Variation in Human Papillomavirus Vaccine Uptake in Men and Women: An Online Survey Using Facebook Recruitment
Background: Federally funded surveys of human papillomavirus (HPV) vaccine uptake are important for pinpointing geographically based health disparities. Although national and state level data are available, local (ie, county and postal code level) data are not due to small sample sizes, confidentiality concerns, and cost. Local level HPV vaccine uptake data may be feasible to obtain by targeting specific geographic areas through social media advertising and recruitment strategies, in combination with online surveys.
Objective: Our goal was to use Facebook-based recruitment and online surveys to estimate local variation in HPV vaccine uptake among young men and women in Minnesota.
Methods: From November 2012 to January 2013, men and women were recruited via a targeted Facebook advertisement campaign to complete an online survey about HPV vaccination practices. The Facebook advertisements were targeted to recruit men and women by location (25 mile radius of Minneapolis, Minnesota, United States), age (18-30 years), and language (English).
Results: Of the 2079 men and women who responded to the Facebook advertisements and visited the study website, 1003 (48.2%) enrolled in the study and completed the survey. The average advertising cost per completed survey was US $1.36. Among those who reported their postal code, 90.6% (881/972) of the participants lived within the previously defined geographic study area. Receipt of 1 dose or more of HPV vaccine was reported by 65.6% women (351/535), and 13.0% (45/347) of men. These results differ from previously reported Minnesota state level estimates (53.8% for young women and 20.8% for young men) and from national estimates (34.5% for women and 2.3% for men).
Conclusions: This study shows that recruiting a representative sample of young men and women based on county and postal code location to complete a survey on HPV vaccination uptake via the Internet is a cost-effective and feasible strategy. This study also highlights the need for local estimates to assess the variation in HPV vaccine uptake, as these estimates differ considerably from those obtained using survey data that are aggregated to the state or federal level.
J Med Internet Res 2014;16(9):e198)
- online recruitment;
- social media;
- local estimation;
- geographic variability;
- human papillomavirus;
Human papillomavirus (HPV) is the most common sexually transmitted infection in the United States  and is the necessary cause of cervical cancer [ ]. HPV infections are also associated with other cancers (eg, anogenital and oropharyngeal) as well as genital warts [ , ]. In total, it is estimated that 5.2% of cancers in men and women worldwide are attributable to HPV [ ].
Two vaccinations against HPV infection are currently licensed in the United States. The vaccinations were originally licensed for use in girls, but as of October 2011, the Advisory Committee on Immunization Practices extended their recommendation of the quadrivalent vaccine to include both boys and girls aged 11 or 12 years old [, ]. However, vaccine uptake has been far lower than expected, with only about half of eligible young women receiving at least one dose of the vaccine [ ]. Initiation of the HPV vaccine series has been shown to be higher among minority adolescent girls; however, completion of the three-dose series is substantially lower among black and Hispanic adolescent girls compared to white adolescent girls [ ]. Although male vaccination data are very limited (due to a later date of approval of the HPV vaccine for boys), racial and income differences in terms of vaccine series initiation and completion have also been observed among adolescent boys [ ].
Previous research on HPV vaccine coverage has used publicly available data from five national health surveys (National Survey of Family Growth, National Immunization Survey [NIS]-Teen, National Health and Nutrition Examination Survey, National Health Interview Survey [NHIS], and the Behavioral Risk Factor Surveillance System) [- ]. These surveys are designed to gather information on a variety of health topics and ask only a few questions regarding HPV vaccination. However, none of these surveys address cervical cancer screening practices and potential barriers to screening or HPV vaccine receipt. In addition, due to the small number of responses in many geographic areas, local data from these surveys are routinely suppressed and aggregated to state boundaries in order to protect the confidentiality of survey respondents, which means that variations at a local level (ie, between counties or postal codes) cannot be adequately assessed. Further, these surveys have, to date, primarily surveyed adolescent girls; HPV vaccination practice data of adolescent boys are limited [ ].
The Internet provides a unique point of contact to reach young adults for health research. Several studies have demonstrated that Internet-based research can be used to elicit high response rates at a fraction of the cost of traditional recruitment methods [- ]. In addition, it has been shown that when compared to in-person interviews, Internet-based surveys have the potential to reach more respondents, include otherwise inaccessible populations, and reduce bias in responses as respondents may be willing to report more sensitive information online compared to in-person interviews [ - ]. A number of studies have also shown that recruitment via Facebook (the leading social media site with more than one billion active users worldwide) can be used to enroll representative samples of the general population [ , - ]. This combination of reach, utility, and reduced cost indicates that social media networks can be a cost-effective medium for research.
The objective of this study was to estimate HPV vaccination practices among a local population of young adult men and women in the United States using an Internet-based recruitment strategy.
Men and women from Minnesota were surveyed about their HPV vaccination practices via the Internet from November 21, 2012, through January 31, 2013. Participants were English-speaking, aged 18-30 years, had a Facebook account, and resided in the greater Twin Cities Metropolitan Area (ie, within 25 miles of downtown Minneapolis, MN). This age range was used to target men and women who were eligible to receive the HPV vaccine, participate in cervical cancer screening (women), and able to provide informed consent. The Twin Cities Metropolitan Area was selected due to the variation of HPV-related cancer incidence rates exhibited in this area during the past 15 years, the high concentration of colleges and universities, and the large population of 18-30 year olds residing in this area . The University of Minnesota Institutional Review Board approved this study.
Facebook Recruitment Campaign
Participants were recruited online via Facebook advertisements (). Tailored advertisements were used to target Facebook users who had profiles that matched the study inclusion criteria. The advertisement criteria were adjusted as needed to target specific postal codes with fewer responses in order to achieve a balanced sample of participants by postal code. Facebook uses an advertisement algorithm that automatically selects the best advertisement to display based on its performance and the advertiser’s bid [ ]; 14 unique advertisements were created and approved by Facebook. For this study, multiple advertisements were submitted for auction simultaneously to create a continuous recruitment window in the event that a particular advertisement performed poorly. Bidding prices and advertisement availability (advertisements can be paused and released at the discretion of the advertiser) were monitored daily and adjusted as necessary until the intended number of completed questionnaires was obtained. The bidding price for advertisements ranged from US $0.75 to US $2.75, with a maximum daily budget of US $50. When a Facebook user clicked on the study advertisement, they were automatically redirected to the secure study website and invited to complete a questionnaire regarding HPV vaccination practices.
The Facebook Ads Manager was used to track the total number of impressions (each time an advertisement was displayed), the number of times an ad was clicked, the average cost-per-click, and the number of people reached (ie, the number of Facebook users that had an opportunity to view one of the study advertisements). Google Analytics software was used to tabulate the total number of visits, the unique visits, the average duration of visits, and the bounce rate (the percentage of visitors that visit a website and leave the site without further browsing) of the study website.
Participants who clicked on a Facebook advertisement were directed to a secured study website and were provided with information regarding the purpose of our study. Participants provided informed consent by clicking on a button that directed them to the study questionnaire. After providing consent, study participants were immediately asked to self-report their age and state of residence. Participants who did not meet the age criteria or who reported that they did not live in Minnesota were considered ineligible and were disqualified from answering the remainder of the questionnaire. Study participants who met the eligibility criteria were also asked to self-report their gender, postal code of their home address, race/ethnicity, highest level of education attained, attendance at religious services, political preferences, sexual orientation, their awareness of HPV, and whether or not they had received the HPV vaccine. Conditional upon participants’ responses, skip logic patterns (ie, participants skip over survey questions that, based on their answers to other questions, do not need to be filled out) were implemented in order to ask applicable follow-up questions regarding the number of shots received, the vaccine type (quadrivalent/bivalent), and reason(s) for not having received the vaccination, as well as future vaccination intentions. Female participants were also asked a series of adaptive questions about past cervical cancer screening. The survey questions regarding HPV vaccination and cancer screening that we used in this study were questions used in the five national surveys mentioned above, in order to facilitate comparisons between studies. Participants were not required to answer every question and could exit the survey at any time. Computer Internet Protocol (IP) addresses were tracked, and multiple entries from the same IP address were not accepted. Survey responses that contained repeated email addresses across multiple survey attempts (n=86) were not accepted. Additionally, 8 surveys that were only partially completed (ie, the participant withdrew) were not included in the analyses. The survey was anonymous and was administered using the online survey assessment tool SurveyMonkey. Eligible respondents who provided informed consent and completed the online survey were emailed an electronic gift card in the amount of US $20 for Target.
Of the 2079 men and women who were recruited via Facebook and visited the study website, 1003 (48.24%) enrolled in the study and completed the survey. Targeted advertising within Facebook based on geographic and age criteria limited the number of ineligible participants (4.4% of all survey attempts) who attempted to access the survey. In total, 86 survey attempts (7.5% of all survey attempts) were identified as duplicate surveys, indicating that an individual attempted to complete the survey more than once (). Facebook advertising and recruitment resulted in an average cost of US $1.36 per completed survey. In addition, 90.6% (881/972) of study participants who self-reported their postal code were located within the recruitment target area (ie, located within a 25-mile radius of downtown Minneapolis, Minnesota; ).
The recruitment target area for this study was a 25-mile radius from downtown Minneapolis, Minnesota. Of the 972 participants who reported their postal code, 881 (90.6%) lived within the recruitment study area.
A total of 1003 participants (557 women and 446 men) completed the online survey. Characteristics of the study population are presented in. With respect to race/ethnicity, the study population was broadly similar to that of 18-34 year-olds in the greater Minneapolis-St. Paul Metropolitan Area based on US Census data. However, due to the inclusion and exclusion criteria, the study population was more educated than the general population of 18-34 year-olds in the Minneapolis-St. Paul Metropolitan Area. In all, 44.2% of respondents (396/896) who knew of the HPV vaccine had been vaccinated against HPV (ie, received ≥1 dose of HPV vaccine), with 65.6% of women (351/535) having been vaccinated with ≥1 dose of HPV vaccine compared to 13.0% of men (45/347). Completion of the HPV vaccine series (ie, receipt of all 3 doses) was reported by 74.9% of women (263/351) and 22.2% of men (10/45) who had ever received an HPV vaccine ( ). Among the 351 women who had received ≥1 dose of HPV vaccine, 265 (75.5%) had also received at least one Pap smear in their lifetime. Of the 479 unvaccinated men and women, 403 (84.1%) were not interested or were unsure about receiving the vaccine in the future.
In this study, we found that recruiting a locally representative sample of young adults via the Internet to participate in a survey about HPV vaccination was cost-effective and efficient. Approximately half of the 2079 individuals that clicked on an advertisement and visited our study website participated and completed our survey at an estimated advertising cost of US $1.36 per enrolled participant. Consistent with other studies, this study found that using the Internet, and in particular social media sites such as Facebook, is successful for recruiting and engaging young adults and hard-to-reach populations for health research [- ]. This method of recruitment is particularly noteworthy given declining response rates from traditional recruitment techniques such as random digit dialing or mailed surveys [ - ]. In addition to higher participation rates, the targeted advertising features embedded within social media websites drastically reduce costs associated with identifying and reaching a large pool of eligible participants [ , , ]. The targeted advertising used in this study also allowed us to collect data within an accelerated timeline (eg, pilot testing of a specific intervention) from a specific geographic location.
Notably, the characteristics of our study population were similar to those of the source population. An estimated 90% of Internet users aged 18-29 years in the United States access social media sites (71% accessed Facebook) in 2013; thus, this finding is likely attributable to the wide reach of social media recruitment . However, our study population was more educated than the general population in the Minneapolis-St. Paul Metropolitan Area, which may be due to the large number of colleges and universities in this area. It cannot be ruled out that people with lower education were less likely to access Facebook and view the advertisements, although other studies have shown that lower income and less educated participants are as likely to participate in Internet-based research studies as those with higher incomes and higher levels of education [ , , ].
In this study, we were also able to collect detailed HPV vaccination data, including participation in screening (for women) and potential barriers to receiving these services among a representative sample of men and women in a defined local geographic area. National surveys including the Behavioral Risk Factor Surveillance System, the NHIS, and the NIS-Teen do not simultaneously assess these factors within the same respondents in their populations. Additionally, these (and other) national surveys aggregate or suppress responses due to participant identification concerns and consequentially local variation and patterns may be obscured. However, HPV vaccine policies, availability, costs, financial assistance, and education materials vary widely across states or even more defined geographic regions . As a result, variation at state and national levels may not reflect the variation in HPV vaccine uptake occurring at a local level.
Of note, the proportion of all adults in this study who had been vaccinated against HPV (ie, received at least one dose of an HPV vaccine) was 45.3% (66.5% for women and 13.0% for men). These estimates are much higher than the HPV vaccine coverage estimates from the 2012 NHIS for women (34.5%) and men (2.3%) aged 19-26 years () [ ]. Although the results for women are more similar to those obtained from the NIS-Teen for girls (53.8%), the estimate for men is much lower than the NIS-Teen estimate for boys (20.8%) aged 13-17 years who received at least one dose of HPV vaccine in 2012 [ ]. Although the differences in the observed rates may be partially explained by the sampling frame, response rates, or the small number of eligible respondents who received the HPV vaccine question series in the national surveys, the estimates of HPV vaccine uptake are noticeably different from the current study.
Limitations include the fact that the survey responses were self-reported by persons over the Internet and may be subject to under or overreporting. However, other Internet-based studies have shown increased self-disclosure and reporting with online surveys, which may reduce potential response biases (eg, interviewer bias or social desirability) [, ]. Additionally, there was no failproof method to ensure that survey responses were unique, and there remains a small probability that some participants responded more than once. We also cannot be certain that those that saw the Facebook advertisements were the same people who completed the survey. The 10% of respondents who were not located within the targeted geographical area may be due to the sharing of the study website with friends, or due to outdated user profiles (ie, Facebook thinks a user lives within the study area and displays the ad although the user has since relocated outside of the target area but has not updated their account info), or because the advertisement algorithm was misspecified by Facebook.
To our knowledge, this is the first study to estimate local level vaccination uptake among young men in the United States. Understanding the local variation and patterns of HPV vaccination of young men could serve to identify areas where HPV infection-related health disparities may continue if neglected. In particular, the online survey also allowed us to collect data on sexual orientation, which in turn would allow us to understand whether men who have sex with men, who are at high risk of HPV-related anal cancer, are receiving the vaccine and to also determine whether reductions in the overall risk of HPV infection will affect transmission to females [, ].
The results from this study suggest that more detailed and local assessments of HPV vaccine uptake are necessary as estimates vary greatly from national surveys. In addition, recruiting young adults via the Internet is efficient, cost-effective, and can produce a representative sample of the target population. Future work is needed to understand the pattern of HPV vaccine uptake at local levels in order to identify areas that may be best served by vaccine programs.
This study was supported by the JB Hawley Student Research Award from the University of Minnesota School of Public Health and by the Minnesota Medical Foundation through Grant 4120-9227-12.
EN and SK conceived and designed the study. EN conducted the data collection and drafted the manuscript. JH, JP, and JMO assisted in the survey design, supervised the statistical analysis, and assisted in reviewing/revising the manuscript. SK provided contributions to the concept and analytical approach for the article and oversaw the analysis, interpretation, and reviewing/revising of the manuscript.
Conflicts of Interest
- Weinstock H, Berman S, Cates W. Sexually transmitted diseases among American youth: incidence and prevalence estimates, 2000. Perspect Sex Reprod Health 2004;36(1):6-10. [CrossRef] [Medline]
- Walboomers JM, Jacobs MV, Manos MM, Bosch FX, Kummer JA, Shah KV, et al. Human papillomavirus is a necessary cause of invasive cervical cancer worldwide. J Pathol 1999 Sep;189(1):12-19. [CrossRef] [Medline]
- Centers for Disease Control and Prevention (CDC). Human papillomavirus-associated cancers - United States, 2004-2008. MMWR Morb Mortal Wkly Rep 2012 Apr 20;61:258-261 [FREE Full text] [Medline]
- Saraiya M, Ahmed F, White M, Lawson H, Unger ER, Eheman C. Toward using National Cancer Surveillance data for preventing and controlling cervical and other human papillomavirus-associated cancers in the US. Cancer 2008 Nov 15;113(10 Suppl):2837-2840 [FREE Full text] [CrossRef] [Medline]
- Parkin DM. The global health burden of infection-associated cancers in the year 2002. Int J Cancer 2006 Jun 15;118(12):3030-3044. [CrossRef] [Medline]
- Centers for Disease Control and Prevention (CDC). FDA licensure of bivalent human papillomavirus vaccine (HPV2, Cervarix) for use in females and updated HPV vaccination recommendations from the Advisory Committee on Immunization Practices (ACIP). MMWR Morb Mortal Wkly Rep 2010 May 28;59(20):626-629 [FREE Full text] [Medline]
- Advisory Committee on Immunization Practices. Recommended adult immunization schedule: United States, 2012. Ann Intern Med 2012 Feb 7;156(3):211-217. [CrossRef] [Medline]
- Centers for Disease Control and Prevention (CDC). National and state vaccination coverage among adolescents aged 13-17 years--United States, 2012. MMWR Morb Mortal Wkly Rep 2013 Aug 30;62(34):685-693 [FREE Full text] [Medline]
- Niccolai LM, Mehta NR, Hadler JL. Racial/Ethnic and poverty disparities in human papillomavirus vaccination completion. Am J Prev Med 2011 Oct;41(4):428-433. [CrossRef] [Medline]
- Jeudin P, Liveright E, Del Carmen MG, Perkins RB. Race, ethnicity, and income factors impacting human papillomavirus vaccination rates. Clin Ther 2014 Jan 1;36(1):24-37. [CrossRef] [Medline]
- Laz TH, Rahman M, Berenson AB. Human papillomavirus vaccine uptake among 18- to 26-year-old women in the United States: National Health Interview Survey, 2010. Cancer 2013 Apr 1;119(7):1386-1392 [FREE Full text] [CrossRef] [Medline]
- Liddon NC, Leichliter JS, Markowitz LE. Human papillomavirus vaccine and sexual behavior among adolescent and young women. Am J Prev Med 2012 Jan;42(1):44-52. [CrossRef] [Medline]
- Pruitt SL, Schootman M. Geographic disparity, area poverty, and human papillomavirus vaccination. Am J Prev Med 2010 May;38(5):525-533 [FREE Full text] [CrossRef] [Medline]
- Wei F, Moore PC, Green AL. Geographic variability in human papillomavirus vaccination among U.S. young women. Am J Prev Med 2013 Feb;44(2):154-157 [FREE Full text] [CrossRef] [Medline]
- Anhang Price R, Tiro JA, Saraiya M, Meissner H, Breen N. Use of human papillomavirus vaccines among young adult women in the United States: an analysis of the 2008 National Health Interview Survey. Cancer 2011 Dec 15;117(24):5560-5568 [FREE Full text] [CrossRef] [Medline]
- Fenner Y, Garland SM, Moore EE, Jayasinghe Y, Fletcher A, Tabrizi SN, et al. Web-based recruiting for health research using a social networking site: an exploratory study. J Med Internet Res 2012;14(1):e20 [FREE Full text] [CrossRef] [Medline]
- Ramo DE, Prochaska JJ. Broad reach and targeted recruitment using Facebook for an online survey of young adult substance use. J Med Internet Res 2012;14(1):e28 [FREE Full text] [CrossRef] [Medline]
- Graham AL, Milner P, Saul JE, Pfaff L. Online advertising as a public health and recruitment tool: comparison of different media campaigns to increase demand for smoking cessation interventions. J Med Internet Res 2008;10(5):e50 [FREE Full text] [CrossRef] [Medline]
- Cantrell MA, Lupinacci P. Methodological issues in online data collection. J Adv Nurs 2007 Dec;60(5):544-549. [CrossRef] [Medline]
- McCabe SE, Boyd CJ, Couper MP, Crawford S, D'Arcy H. Mode effects for collecting alcohol and other drug use data: Web and U.S. mail. J Stud Alcohol 2002 Nov;63(6):755-761. [Medline]
- Rhodes SD, Bowie DA, Hergenrather KC. Collecting behavioural data using the world wide web: considerations for researchers. J Epidemiol Community Health 2003 Jan;57(1):68-73 [FREE Full text] [Medline]
- Schonlau M, Zapert K, Simon Lp, Sanstad Kh, Marcus Sm, Adams J, et al. A Comparison Between Responses From a Propensity-Weighted Web Survey and an Identical RDD Survey. Soc Sci Comput Rev 2004 Feb 01;22(1):128-138. [CrossRef]
- Schonlau M. Are "webographic" or attitudinal questions useful for adjusting estimates from Web surveys using propensity scoring? Surv Res Methods 2007;1(3):155-163 [FREE Full text] [WebCite Cache]
- Thériault N, Bi P, Hiller JE, Nor M. Use of web 2.0 to recruit Australian gay men to an online HIV/AIDS survey. J Med Internet Res 2012;14(6):e149 [FREE Full text] [CrossRef] [Medline]
- Im EO, Chee W. Recruitment of research participants through the Internet. Comput Inform Nurs 2004;22(5):289-297. [Medline]
- Jones L, Saksvig BI, Grieser M, Young DR. Recruiting adolescent girls into a follow-up study: benefits of using a social networking website. Contemp Clin Trials 2012 Mar;33(2):268-272 [FREE Full text] [CrossRef] [Medline]
- Facebook. Community Info. 2014. URL: http://newsroom.fb.com/company-info/ [accessed 2014-04-30] [WebCite Cache]
- Batterham PJ. Recruitment of mental health survey participants using Internet advertising: content, characteristics and cost effectiveness. Int J Methods Psychiatr Res 2014 Jun;23(2):184-191. [CrossRef] [Medline]
- Frandsen M, Walters J, Ferguson SG. Exploring the viability of using online social media advertising as a recruitment method for smoking cessation clinical trials. Nicotine Tob Res 2014 Feb;16(2):247-251. [CrossRef] [Medline]
- Ramo DE, Liu H, Prochaska JJ. Reliability and validity of young adults' anonymous online reports of marijuana use and thoughts about use. Psychol Addict Behav 2012 Dec;26(4):801-811 [FREE Full text] [CrossRef] [Medline]
- Nelson EJ, Hughes J, Kulasingam SL. Spatial patterns of human papillomavirus-associated cancers within the state of Minnesota, 1998-2007. Spat Spatiotemporal Epidemiol 2014 Jun;9:13-21. [CrossRef] [Medline]
- Facebook. Campaign Cost and Budgeting. 2014. URL: https://www.facebook.com/unsupportedbrowser [accessed 2014-05-01] [WebCite Cache]
- van Gelder MM, Bretveld RW, Roeleveld N. Web-based questionnaires: the future in epidemiology? Am J Epidemiol 2010 Dec 1;172(11):1292-1298 [FREE Full text] [CrossRef] [Medline]
- Morton LM, Cahill J, Hartge P. Reporting participation in epidemiologic studies: a survey of practice. Am J Epidemiol 2006 Feb 1;163(3):197-203 [FREE Full text] [CrossRef] [Medline]
- Galea S, Tracy M. Participation rates in epidemiologic studies. Ann Epidemiol 2007 Sep;17(9):643-653. [CrossRef] [Medline]
- Pew Research Internet Project. Social Networking Fact Sheet. 2014. URL: http://www.pewinternet.org/fact-sheets/social-networking-fact-sheet/ [accessed 2014-04-23] [WebCite Cache]
- Lohse B. Facebook is an effective strategy to recruit low-income women to online nutrition education. J Nutr Educ Behav 2013;45(1):69-76. [CrossRef] [Medline]
- Kesse-Guyot E, Andreeva V, Castetbon K, Vernay M, Touvier M, Méjean C, et al. Participant profiles according to recruitment source in a large Web-based prospective study: experience from the Nutrinet-Santé study. J Med Internet Res 2013;15(9):e205 [FREE Full text] [CrossRef] [Medline]
- Katz ML, Reiter PL, Kluhsman BC, Kennedy S, Dwyer S, Schoenberg N, et al. Human papillomavirus (HPV) vaccine availability, recommendations, cost, and policies among health departments in seven Appalachian states. Vaccine 2009 May 21;27(24):3195-3200 [FREE Full text] [CrossRef] [Medline]
- Williams WW, Lu PJ, O'Halloran A, Bridges CB, Pilishvili T, Hales CM, Centers for Disease Control and Prevention (CDC). Noninfluenza vaccination coverage among adults - United States, 2012. MMWR Morb Mortal Wkly Rep 2014 Feb 7;63(5):95-102 [FREE Full text] [Medline]
- Centers for Disease Control and Prevention (CDC). National and state vaccination coverage among adolescents aged 13-17 years--United States, 2012. MMWR Morb Mortal Wkly Rep 2013 Aug 30;62(34):685-693 [FREE Full text] [Medline]
- Palefsky JM. Human papillomavirus-related disease in men: not just a women's issue. J Adolesc Health 2010 Apr;46(4 Suppl):S12-S19 [FREE Full text] [CrossRef] [Medline]
- Watson M, Saraiya M, Ahmed F, Cardinez CJ, Reichman ME, Weir HK, et al. Using population-based cancer registry data to assess the burden of human papillomavirus-associated cancers in the United States: overview of methods. Cancer 2008 Nov 15;113(10 Suppl):2841-2854 [FREE Full text] [CrossRef] [Medline]
|HPV: human papillomavirus|
|IP: Internet Protocol|
|NHIS: National Health Interview Survey|
|NIS: National Immunization Survey|
Edited by G Eysenbach; submitted 01.05.14; peer-reviewed by M Frandsen, Y Jayasinghe; comments to author 16.07.14; revised version received 13.08.14; accepted 16.08.14; published 01.09.14
©Erik J Nelson, John Hughes, J Michael Oakes, James S Pankow, Shalini L Kulasingam. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 01.09.2014.
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